diff options
| author | Vladimir Azarov <avm@intermediate-node.net> | 2025-05-14 03:19:35 +0200 |
|---|---|---|
| committer | Vladimir Azarov <avm@intermediate-node.net> | 2025-05-14 03:19:35 +0200 |
| commit | 3d568063a49204193009ad6a2637176b38902525 (patch) | |
| tree | a29e144f61133c7cd505f3657ae4abf27b12f19f | |
| parent | 52a6f8656e8a600a2c59fa2802fb46fafb30de45 (diff) | |
Printf
| -rw-r--r-- | common.sml | 60 | ||||
| -rw-r--r-- | doc/c89-draft.html | 15360 | ||||
| -rw-r--r-- | driver.fun | 2 | ||||
| -rw-r--r-- | exn_handler.fun | 12 | ||||
| -rw-r--r-- | hashtable.sig | 7 | ||||
| -rw-r--r-- | hashtable.sml | 111 | ||||
| -rw-r--r-- | ppc.fun | 298 | ||||
| -rw-r--r-- | stream.sml | 4 | ||||
| -rw-r--r-- | tokenizer.fun | 32 | ||||
| -rw-r--r-- | tokenizer.sig | 2 |
10 files changed, 15667 insertions, 221 deletions
@@ -5,32 +5,6 @@ infixr 0 $ fun assert truth = if not truth then raise Unreachable else () -local - val lastIsNL = ref true - - fun endsWith s = - String.sub (s, String.size s - 1) = #"\n" handle - Subscript => raise Unreachable - - val print' = print -in - fun print s = ( - lastIsNL := endsWith s; - print' s - ) - - fun printLn s = ( - lastIsNL := true; - print' s; print "\n" - ) - - fun printOnNL s = ( - if not $ !lastIsNL then print' "\n" else (); - print' s; - lastIsNL := endsWith s - ) -end - (* All global values which computations may raise an exception must be * wrapped in lazy, so that no exception is thrown before custom * top-level handler is set. @@ -57,11 +31,14 @@ in | Exn e => raise e end -structure FRU = struct +structure Fold = struct fun fold (a, f) g = g (a, f) fun step0 h (a, f) = fold (h a, f) + fun step1 h (a, f) b = fold (h (b, a), f) fun step2 h (a, f) b c = fold (h (b, c, a), f) +end +structure FRU = struct fun next g (f, z) x = g (f x, z) fun f1 (f, z) x = f (z x) fun f2 z = next f1 z @@ -89,7 +66,7 @@ structure FRU = struct fun ops () = cX from' fun vars f = to f record in - fold ((vars, ops), fn (vars, _) => vars from) + Fold.fold ((vars, ops), fn (vars, _) => vars from) end fun makeUpdate0 z = makeUpdate c0 z fun makeUpdate1 z = makeUpdate c1 z @@ -102,19 +79,38 @@ structure FRU = struct fun makeUpdate8 z = makeUpdate c8 z fun makeUpdate9 z = makeUpdate c9 z - fun upd z = step2 + fun upd z = Fold.step2 (fn (s, f, (vars, ops)) => (fn out => vars (s (ops ()) (out, f)), ops)) z - fun set z = step2 + fun set z = Fold.step2 (fn (s, v, (vars, ops)) => (fn out => vars (s (ops ()) (out, fn _ => v)), ops)) z - fun set2 s v = step0 + fun set2 s v = Fold.step0 (fn (vars, ops) => (fn out => vars (s (ops ()) (out, fn _ => v)), ops)) - fun upd2 s f = step0 + fun upd2 s f = Fold.step0 (fn (vars, ops) => (fn out => vars (s (ops ()) (out, f)), ops)) end fun % (a, f) = f a val s = FRU.set val u = FRU.upd + +fun output s = TextIO.output (TextIO.stdOut, s) +local + fun printBuffer _ [] = () + | printBuffer stream (s :: acc) = + (TextIO.output (stream, s); printBuffer stream acc) +in + fun fprintf stream f = Fold.fold + ((stream, []), fn (stream, acc) => printBuffer stream (rev acc)) f + fun printf f = fprintf TextIO.stdOut f + + fun ` z = Fold.step1 (fn (str, (s, acc)) => (s, str :: acc)) z + fun A0 z = Fold.step1 (fn (f, (s, a)) => (s, f () :: a)) z + fun A1 z = Fold.step2 (fn (f, v, (s, a)) => (s, f v :: a)) z + fun bind A f = fn z => Fold.fold z A f + + val C = fn z => bind A1 str z + val I = fn z => bind A1 Int.toString z +end diff --git a/doc/c89-draft.html b/doc/c89-draft.html new file mode 100644 index 0000000..c86e957 --- /dev/null +++ b/doc/c89-draft.html @@ -0,0 +1,15360 @@ +<HTML>
+<HEAD>
+<!-- Meta http equivalent was here -->
+<TITLE>The C89 Draft</TITLE>
+<LINK href="c89-draft.css" rel="stylesheet"></HEAD>
+<BODY>
+<H1>The C89 Draft</H1>
+<FONT size="-1">
+<UL>
+<LI><A href="
+ #1.">1. INTRODUCTION</A></LI>
+<UL>
+<LI><A href="
+ #1.1">1.1 PURPOSE</A></LI>
+<UL>
+</UL><LI><A href="
+ #1.2">1.2 SCOPE</A></LI>
+<UL>
+</UL><LI><A href="
+ #1.3">1.3 REFERENCES</A></LI>
+<UL>
+</UL><LI><A href="
+ #1.4">1.4 ORGANIZATION OF THE DOCUMENT</A></LI>
+<UL>
+</UL><LI><A href="
+ #1.5">1.5 BASE DOCUMENTS</A></LI>
+<UL>
+</UL><LI><A href="
+ #1.6">1.6 DEFINITIONS OF TERMS</A></LI>
+<UL>
+</UL><LI><A href="
+ #1.7">1.7 COMPLIANCE</A></LI>
+<UL>
+</UL><LI><A href="
+ #1.8">1.8 FUTURE DIRECTIONS</A></LI>
+<UL>
+</UL><LI><A href="
+ #1.9">1.9 ABOUT THIS DRAFT</A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #2.">2. ENVIRONMENT</A></LI>
+<UL>
+<LI><A href="
+ #2.1">2.1 CONCEPTUAL MODELS</A></LI>
+<UL>
+<LI><A href="
+ #2.1.1">2.1.1 Translation environment</A></LI>
+<UL>
+<LI><A href="
+ #2.1.1.1">2.1.1.1 Program structure</A></LI><LI><A href="
+ #2.1.1.2">2.1.1.2 Translation phases</A></LI><LI><A href="
+ #2.1.1.3">2.1.1.3 Diagnostics</A></LI></UL><LI><A href="
+ #2.1.2">2.1.2 Execution environments</A></LI>
+<UL>
+<LI><A href="
+ #2.1.2.1">2.1.2.1 Freestanding environment</A></LI><LI><A href="
+ #2.1.2.2">2.1.2.2 Hosted environment</A></LI><LI><A href="
+ #2.1.2.3">2.1.2.3 Program execution</A></LI></UL></UL><LI><A href="
+ #2.2">2.2 ENVIRONMENTAL CONSIDERATIONS</A></LI>
+<UL>
+<LI><A href="
+ #2.2.1">2.2.1 Character sets</A></LI>
+<UL>
+<LI><A href="
+ #2.2.1.1">2.2.1.1 Trigraph sequences</A></LI><LI><A href="
+ #2.2.1.2">2.2.1.2 Multibyte characters</A></LI></UL><LI><A href="
+ #2.2.2">2.2.2 Character display semantics</A></LI>
+<UL>
+</UL><LI><A href="
+ #2.2.3">2.2.3 Signals and interrupts</A></LI>
+<UL>
+</UL><LI><A href="
+ #2.2.4">2.2.4 Environmental limits</A></LI>
+<UL>
+<LI><A href="
+ #2.2.4.1">2.2.4.1 Translation limits</A></LI><LI><A href="
+ #2.2.4.2">2.2.4.2 Numerical limits</A></LI></UL></UL></UL><LI><A href="
+ #3.">3. LANGUAGE</A></LI>
+<UL>
+<LI><A href="
+ #3.1">3.1 LEXICAL ELEMENTS</A></LI>
+<UL>
+<LI><A href="
+ #3.1.1">3.1.1 Keywords</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.1.2">3.1.2 Identifiers</A></LI>
+<UL>
+<LI><A href="
+ #3.1.2.1">3.1.2.1 Scopes of identifiers</A></LI><LI><A href="
+ #3.1.2.2">3.1.2.2 Linkages of identifiers</A></LI><LI><A href="
+ #3.1.2.3">3.1.2.3 Name spaces of identifiers</A></LI><LI><A href="
+ #3.1.2.4">3.1.2.4 Storage durations of objects</A></LI><LI><A href="
+ #3.1.2.5">3.1.2.5 Types</A></LI><LI><A href="
+ #3.1.2.6">3.1.2.6 Compatible type and composite type</A></LI></UL><LI><A href="
+ #3.1.3">3.1.3 Constants</A></LI>
+<UL>
+<LI><A href="
+ #3.1.3.1">3.1.3.1 Floating constants</A></LI><LI><A href="
+ #3.1.3.2">3.1.3.2 Integer constants</A></LI><LI><A href="
+ #3.1.3.3">3.1.3.3 Enumeration constants</A></LI><LI><A href="
+ #3.1.3.4">3.1.3.4 Character constants</A></LI></UL><LI><A href="
+ #3.1.4">3.1.4 String literals</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.1.5">3.1.5 Operators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.1.6">3.1.6 Punctuators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.1.7">3.1.7 Header names</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.1.8">3.1.8 Preprocessing numbers</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.1.9">3.1.9 Comments</A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #3.2">3.2 CONVERSIONS</A></LI>
+<UL>
+<LI><A href="
+ #3.2.1">3.2.1 Arithmetic operands</A></LI>
+<UL>
+<LI><A href="
+ #3.2.1.1">3.2.1.1 Characters and integers</A></LI><LI><A href="
+ #3.2.1.2">3.2.1.2 Signed and unsigned integers</A></LI><LI><A href="
+ #3.2.1.3">3.2.1.3 Floating and integral</A></LI><LI><A href="
+ #3.2.1.4">3.2.1.4 Floating types</A></LI><LI><A href="
+ #3.2.1.5">3.2.1.5 Usual arithmetic conversions</A></LI></UL><LI><A href="
+ #3.2.2">3.2.2 Other operands</A></LI>
+<UL>
+<LI><A href="
+ #3.2.2.1">3.2.2.1 Lvalues and function designators</A></LI><LI><A href="
+ #3.2.2.2">3.2.2.2 void</A></LI><LI><A href="
+ #3.2.2.3">3.2.2.3 Pointers</A></LI></UL></UL><LI><A href="
+ #3.3">3.3 EXPRESSIONS</A></LI>
+<UL>
+<LI><A href="
+ #3.3.1">3.3.1 Primary expressions</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.2">3.3.2 Postfix operators</A></LI>
+<UL>
+<LI><A href="
+ #3.3.2.1">3.3.2.1 Array subscripting</A></LI><LI><A href="
+ #3.3.2.2">3.3.2.2 Function calls</A></LI><LI><A href="
+ #3.3.2.3">3.3.2.3 Structure and union members</A></LI><LI><A href="
+ #3.3.2.4">3.3.2.4 Postfix increment and decrement operators</A></LI></UL><LI><A href="
+ #3.3.3">3.3.3 Unary operators</A></LI>
+<UL>
+<LI><A href="
+ #3.3.3.1">3.3.3.1 Prefix increment and decrement operators</A></LI><LI><A href="
+ #3.3.3.2">3.3.3.2 Address and indirection operators</A></LI><LI><A href="
+ #3.3.3.3">3.3.3.3 Unary arithmetic operators</A></LI><LI><A href="
+ #3.3.3.4">3.3.3.4 The sizeof operator</A></LI></UL><LI><A href="
+ #3.3.4">3.3.4 Cast operators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.5">3.3.5 Multiplicative operators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.6">3.3.6 Additive operators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.7">3.3.7 Bitwise shift operators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.8">3.3.8 Relational operators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.9">3.3.9 Equality operators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.10">3.3.10 Bitwise AND operator</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.11">3.3.11 Bitwise exclusive OR operator</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.12">3.3.12 Bitwise inclusive OR operator</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.13">3.3.13 Logical AND operator</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.14">3.3.14 Logical OR operator</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.15">3.3.15 Conditional operator</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.3.16">3.3.16 Assignment operators</A></LI>
+<UL>
+<LI><A href="
+ #3.3.16.1">3.3.16.1 Simple assignment</A></LI><LI><A href="
+ #3.3.16.2">3.3.16.2 Compound assignment</A></LI></UL><LI><A href="
+ #3.3.17">3.3.17 Comma operator</A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #3.4">3.4 CONSTANT EXPRESSIONS</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.5">3.5 DECLARATIONS</A></LI>
+<UL>
+<LI><A href="
+ #3.5.1">3.5.1 Storage-class specifiers</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.5.2">3.5.2 Type specifiers</A></LI>
+<UL>
+<LI><A href="
+ #3.5.2.1">3.5.2.1 Structure and union specifiers</A></LI><LI><A href="
+ #3.5.2.2">3.5.2.2 Enumeration specifiers</A></LI><LI><A href="
+ #3.5.2.3">3.5.2.3 Tags</A></LI></UL><LI><A href="
+ #3.5.3">3.5.3 Type qualifiers</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.5.4">3.5.4 Declarators</A></LI>
+<UL>
+<LI><A href="
+ #3.5.4.1">3.5.4.1 Pointer declarators</A></LI><LI><A href="
+ #3.5.4.2">3.5.4.2 Array declarators</A></LI><LI><A href="
+ #3.5.4.3">3.5.4.3 Function declarators (including prototypes)</A></LI></UL><LI><A href="
+ #3.5.5">3.5.5 Type names</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.5.6">3.5.6 Type definitions</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.5.7">3.5.7 Initialization</A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #3.6">3.6 STATEMENTS</A></LI>
+<UL>
+<LI><A href="
+ #3.6.1">3.6.1 Labeled statements</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.6.2">3.6.2 Compound statement, or block</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.6.3">3.6.3 Expression and null statements</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.6.4">3.6.4 Selection statements</A></LI>
+<UL>
+<LI><A href="
+ #3.6.4.1">3.6.4.1 The if statement</A></LI><LI><A href="
+ #3.6.4.2">3.6.4.2 The switch statement</A></LI></UL><LI><A href="
+ #3.6.5">3.6.5 Iteration statements</A></LI>
+<UL>
+<LI><A href="
+ #3.6.5.1">3.6.5.1 The while statement</A></LI><LI><A href="
+ #3.6.5.2">3.6.5.2 The do statement</A></LI><LI><A href="
+ #3.6.5.3">3.6.5.3 The for statement</A></LI></UL><LI><A href="
+ #3.6.6">3.6.6 Jump statements</A></LI>
+<UL>
+<LI><A href="
+ #3.6.6.1">3.6.6.1 The goto statement</A></LI><LI><A href="
+ #3.6.6.2">3.6.6.2 The continue statement</A></LI><LI><A href="
+ #3.6.6.3">3.6.6.3 The break statement</A></LI><LI><A href="
+ #3.6.6.4">3.6.6.4 The return statement</A></LI></UL></UL><LI><A href="
+ #3.7">3.7 EXTERNAL DEFINITIONS</A></LI>
+<UL>
+<LI><A href="
+ #3.7.1">3.7.1 Function definitions</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.7.2">3.7.2 External object definitions</A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #3.8">3.8 PREPROCESSING DIRECTIVES</A></LI>
+<UL>
+<LI><A href="
+ #3.8.1">3.8.1 Conditional inclusion</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.8.2">3.8.2 Source file inclusion</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.8.3">3.8.3 Macro replacement</A></LI>
+<UL>
+<LI><A href="
+ #3.8.3.1">3.8.3.1 Argument substitution</A></LI><LI><A href="
+ #3.8.3.2">3.8.3.2 The # operator</A></LI><LI><A href="
+ #3.8.3.3">3.8.3.3 The ## operator</A></LI><LI><A href="
+ #3.8.3.4">3.8.3.4 Rescanning and further replacement</A></LI><LI><A href="
+ #3.8.3.5">3.8.3.5 Scope of macro definitions</A></LI></UL><LI><A href="
+ #3.8.4">3.8.4 Line control</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.8.5">3.8.5 Error directive</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.8.6">3.8.6 Pragma directive</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.8.7">3.8.7 Null directive</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.8.8">3.8.8 Predefined macro names</A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #3.9">3.9 FUTURE LANGUAGE DIRECTIONS</A></LI>
+<UL>
+<LI><A href="
+ #3.9.1">3.9.1 External names</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.9.2">3.9.2 Character escape sequences</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.9.3">3.9.3 Storage-class specifiers</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.9.4">3.9.4 Function declarators</A></LI>
+<UL>
+</UL><LI><A href="
+ #3.9.5">3.9.5 Function definitions</A></LI>
+<UL>
+</UL></UL></UL><LI><A href="
+ #4.">4. LIBRARY</A></LI>
+<UL>
+<LI><A href="
+ #4.1">4.1 INTRODUCTION</A></LI>
+<UL>
+<LI><A href="
+ #4.1.1">4.1.1 Definitions of terms</A></LI>
+<UL>
+</UL><LI><A href="
+ #4.1.2">4.1.2 Standard headers</A></LI>
+<UL>
+</UL><LI><A href="
+ #4.1.3">4.1.3 Errors <errno.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.1.4">4.1.4 Limits <float.h> and <limits.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.1.5">4.1.5 Common definitions <stddef.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.1.6">4.1.6 Use of library functions</A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #4.2">4.2 DIAGNOSTICS <assert.h></A></LI>
+<UL>
+<LI><A href="
+ #4.2.1">4.2.1 Program diagnostics</A></LI>
+<UL>
+<LI><A href="
+ #4.2.1.1">4.2.1.1 The assert macro</A></LI></UL></UL><LI><A href="
+ #4.3">4.3 CHARACTER HANDLING <ctype.h></A></LI>
+<UL>
+<LI><A href="
+ #4.3.1">4.3.1 Character testing functions</A></LI>
+<UL>
+<LI><A href="
+ #4.3.1.1">4.3.1.1 The isalnum function</A></LI><LI><A href="
+ #4.3.1.2">4.3.1.2 The isalpha function</A></LI><LI><A href="
+ #4.3.1.3">4.3.1.3 The iscntrl function</A></LI><LI><A href="
+ #4.3.1.4">4.3.1.4 The isdigit function</A></LI><LI><A href="
+ #4.3.1.5">4.3.1.5 The isgraph function</A></LI><LI><A href="
+ #4.3.1.6">4.3.1.6 The islower function</A></LI><LI><A href="
+ #4.3.1.7">4.3.1.7 The isprint function</A></LI><LI><A href="
+ #4.3.1.8">4.3.1.8 The ispunct function</A></LI><LI><A href="
+ #4.3.1.9">4.3.1.9 The isspace function</A></LI><LI><A href="
+ #4.3.1.10">4.3.1.10 The isupper function</A></LI><LI><A href="
+ #4.3.1.11">4.3.1.11 The isxdigit function</A></LI></UL><LI><A href="
+ #4.3.2">4.3.2 Character case mapping functions</A></LI>
+<UL>
+<LI><A href="
+ #4.3.2.1">4.3.2.1 The tolower function</A></LI><LI><A href="
+ #4.3.2.2">4.3.2.2 The toupper function</A></LI></UL></UL><LI><A href="
+ #4.4">4.4 LOCALIZATION <locale.h></A></LI>
+<UL>
+<LI><A href="
+ #4.4.1">4.4.1 Locale control</A></LI>
+<UL>
+<LI><A href="
+ #4.4.1.1">4.4.1.1 The setlocale function</A></LI></UL><LI><A href="
+ #4.4.2">4.4.2 Numeric formatting convention inquiry</A></LI>
+<UL>
+<LI><A href="
+ #4.4.2.1">4.4.2.1 The localeconv function</A></LI></UL></UL><LI><A href="
+ #4.5">4.5 MATHEMATICS <math.h></A></LI>
+<UL>
+<LI><A href="
+ #4.5.1">4.5.1 Treatment of error conditions</A></LI>
+<UL>
+</UL><LI><A href="
+ #4.5.2">4.5.2 Trigonometric functions</A></LI>
+<UL>
+<LI><A href="
+ #4.5.2.1">4.5.2.1 The acos function</A></LI><LI><A href="
+ #4.5.2.2">4.5.2.2 The asin function</A></LI><LI><A href="
+ #4.5.2.3">4.5.2.3 The atan function</A></LI><LI><A href="
+ #4.5.2.4">4.5.2.4 The atan2 function</A></LI><LI><A href="
+ #4.5.2.5">4.5.2.5 The cos function</A></LI><LI><A href="
+ #4.5.2.6">4.5.2.6 The sin function</A></LI><LI><A href="
+ #4.5.2.7">4.5.2.7 The tan function</A></LI></UL><LI><A href="
+ #4.5.3">4.5.3 Hyperbolic functions</A></LI>
+<UL>
+<LI><A href="
+ #4.5.3.1">4.5.3.1 The cosh function</A></LI><LI><A href="
+ #4.5.3.2">4.5.3.2 The sinh function</A></LI><LI><A href="
+ #4.5.3.3">4.5.3.3 The tanh function</A></LI></UL><LI><A href="
+ #4.5.4">4.5.4 Exponential and logarithmic functions</A></LI>
+<UL>
+<LI><A href="
+ #4.5.4.1">4.5.4.1 The exp function</A></LI><LI><A href="
+ #4.5.4.2">4.5.4.2 The frexp function</A></LI><LI><A href="
+ #4.5.4.3">4.5.4.3 The ldexp function</A></LI><LI><A href="
+ #4.5.4.4">4.5.4.4 The log function</A></LI><LI><A href="
+ #4.5.4.5">4.5.4.5 The log10 function</A></LI><LI><A href="
+ #4.5.4.6">4.5.4.6 The modf function</A></LI></UL><LI><A href="
+ #4.5.5">4.5.5 Power functions</A></LI>
+<UL>
+<LI><A href="
+ #4.5.5.1">4.5.5.1 The pow function</A></LI><LI><A href="
+ #4.5.5.2">4.5.5.2 The sqrt function</A></LI></UL><LI><A href="
+ #4.5.6">4.5.6 Nearest integer, absolute value, and remainder functions</A></LI>
+<UL>
+<LI><A href="
+ #4.5.6.1">4.5.6.1 The ceil function</A></LI><LI><A href="
+ #4.5.6.2">4.5.6.2 The fabs function</A></LI><LI><A href="
+ #4.5.6.3">4.5.6.3 The floor function</A></LI><LI><A href="
+ #4.5.6.4">4.5.6.4 The fmod function</A></LI></UL></UL><LI><A href="
+ #4.6">4.6 NON-LOCAL JUMPS <setjmp.h></A></LI>
+<UL>
+<LI><A href="
+ #4.6.1">4.6.1 Save calling environment</A></LI>
+<UL>
+<LI><A href="
+ #4.6.1.1">4.6.1.1 The setjmp macro</A></LI></UL><LI><A href="
+ #4.6.2">4.6.2 Restore calling environment</A></LI>
+<UL>
+<LI><A href="
+ #4.6.2.1">4.6.2.1 The longjmp function</A></LI></UL></UL><LI><A href="
+ #4.7">4.7 SIGNAL HANDLING <signal.h></A></LI>
+<UL>
+<LI><A href="
+ #4.7.1">4.7.1 Specify signal handling</A></LI>
+<UL>
+<LI><A href="
+ #4.7.1.1">4.7.1.1 The signal function</A></LI></UL><LI><A href="
+ #4.7.2">4.7.2 Send signal</A></LI>
+<UL>
+<LI><A href="
+ #4.7.2.1">4.7.2.1 The raise function</A></LI></UL></UL><LI><A href="
+ #4.8">4.8 VARIABLE ARGUMENTS <stdarg.h></A></LI>
+<UL>
+<LI><A href="
+ #4.8.1">4.8.1 Variable argument list access macros</A></LI>
+<UL>
+<LI><A href="
+ #4.8.1.1">4.8.1.1 The va_start macro</A></LI><LI><A href="
+ #4.8.1.2">4.8.1.2 The va_arg macro</A></LI><LI><A href="
+ #4.8.1.3">4.8.1.3 The va_end macro</A></LI></UL></UL><LI><A href="
+ #4.9">4.9 INPUT/OUTPUT <stdio.h></A></LI>
+<UL>
+<LI><A href="
+ #4.9.1">4.9.1 Introduction</A></LI>
+<UL>
+</UL><LI><A href="
+ #4.9.2">4.9.2 Streams</A></LI>
+<UL>
+</UL><LI><A href="
+ #4.9.3">4.9.3 Files</A></LI>
+<UL>
+</UL><LI><A href="
+ #4.9.4">4.9.4 Operations on files</A></LI>
+<UL>
+<LI><A href="
+ #4.9.4.1">4.9.4.1 The remove function</A></LI><LI><A href="
+ #4.9.4.2">4.9.4.2 The rename function</A></LI><LI><A href="
+ #4.9.4.3">4.9.4.3 The tmpfile function</A></LI><LI><A href="
+ #4.9.4.4">4.9.4.4 The tmpnam function</A></LI></UL><LI><A href="
+ #4.9.5">4.9.5 File access functions</A></LI>
+<UL>
+<LI><A href="
+ #4.9.5.1">4.9.5.1 The fclose function</A></LI><LI><A href="
+ #4.9.5.2">4.9.5.2 The fflush function</A></LI><LI><A href="
+ #4.9.5.3">4.9.5.3 The fopen function</A></LI><LI><A href="
+ #4.9.5.4">4.9.5.4 The freopen function</A></LI><LI><A href="
+ #4.9.5.5">4.9.5.5 The setbuf function</A></LI><LI><A href="
+ #4.9.5.6">4.9.5.6 The setvbuf function</A></LI></UL><LI><A href="
+ #4.9.6">4.9.6 Formatted input/output functions</A></LI>
+<UL>
+<LI><A href="
+ #4.9.6.1">4.9.6.1 The fprintf function</A></LI><LI><A href="
+ #4.9.6.2">4.9.6.2 The fscanf function</A></LI><LI><A href="
+ #4.9.6.3">4.9.6.3 The printf function</A></LI><LI><A href="
+ #4.9.6.4">4.9.6.4 The scanf function</A></LI><LI><A href="
+ #4.9.6.5">4.9.6.5 The sprintf function</A></LI><LI><A href="
+ #4.9.6.6">4.9.6.6 The sscanf function</A></LI><LI><A href="
+ #4.9.6.7">4.9.6.7 The vfprintf function</A></LI><LI><A href="
+ #4.9.6.8">4.9.6.8 The vprintf function</A></LI><LI><A href="
+ #4.9.6.9">4.9.6.9 The vsprintf function</A></LI></UL><LI><A href="
+ #4.9.7">4.9.7 Character input/output functions</A></LI>
+<UL>
+<LI><A href="
+ #4.9.7.1">4.9.7.1 The fgetc function</A></LI><LI><A href="
+ #4.9.7.2">4.9.7.2 The fgets function</A></LI><LI><A href="
+ #4.9.7.3">4.9.7.3 The fputc function</A></LI><LI><A href="
+ #4.9.7.4">4.9.7.4 The fputs function</A></LI><LI><A href="
+ #4.9.7.5">4.9.7.5 The getc function</A></LI><LI><A href="
+ #4.9.7.6">4.9.7.6 The getchar function</A></LI><LI><A href="
+ #4.9.7.7">4.9.7.7 The gets function</A></LI><LI><A href="
+ #4.9.7.8">4.9.7.8 The putc function</A></LI><LI><A href="
+ #4.9.7.9">4.9.7.9 The putchar function</A></LI><LI><A href="
+ #4.9.7.10">4.9.7.10 The puts function</A></LI><LI><A href="
+ #4.9.7.11">4.9.7.11 The ungetc function</A></LI></UL><LI><A href="
+ #4.9.8">4.9.8 Direct input/output functions</A></LI>
+<UL>
+<LI><A href="
+ #4.9.8.1">4.9.8.1 The fread function</A></LI><LI><A href="
+ #4.9.8.2">4.9.8.2 The fwrite function</A></LI></UL><LI><A href="
+ #4.9.9">4.9.9 File positioning functions</A></LI>
+<UL>
+<LI><A href="
+ #4.9.9.1">4.9.9.1 The fgetpos function</A></LI><LI><A href="
+ #4.9.9.2">4.9.9.2 The fseek function</A></LI><LI><A href="
+ #4.9.9.3">4.9.9.3 The fsetpos function</A></LI><LI><A href="
+ #4.9.9.4">4.9.9.4 The ftell function</A></LI><LI><A href="
+ #4.9.9.5">4.9.9.5 The rewind function</A></LI></UL><LI><A href="
+ #4.9.10">4.9.10 Error-handling functions</A></LI>
+<UL>
+<LI><A href="
+ #4.9.10.1">4.9.10.1 The clearerr function</A></LI><LI><A href="
+ #4.9.10.2">4.9.10.2 The feof function</A></LI><LI><A href="
+ #4.9.10.3">4.9.10.3 The ferror function</A></LI><LI><A href="
+ #4.9.10.4">4.9.10.4 The perror function</A></LI></UL></UL><LI><A href="
+ #4.10">4.10 GENERAL UTILITIES <stdlib.h></A></LI>
+<UL>
+<LI><A href="
+ #4.10.1">4.10.1 String conversion functions</A></LI>
+<UL>
+<LI><A href="
+ #4.10.1.1">4.10.1.1 The atof function</A></LI><LI><A href="
+ #4.10.1.2">4.10.1.2 The atoi function</A></LI><LI><A href="
+ #4.10.1.3">4.10.1.3 The atol function</A></LI><LI><A href="
+ #4.10.1.4">4.10.1.4 The strtod function</A></LI><LI><A href="
+ #4.10.1.5">4.10.1.5 The strtol function</A></LI><LI><A href="
+ #4.10.1.6">4.10.1.6 The strtoul function</A></LI></UL><LI><A href="
+ #4.10.2">4.10.2 Pseudo-random sequence generation functions</A></LI>
+<UL>
+<LI><A href="
+ #4.10.2.1">4.10.2.1 The rand function</A></LI><LI><A href="
+ #4.10.2.2">4.10.2.2 The srand function</A></LI></UL><LI><A href="
+ #4.10.3">4.10.3 Memory management functions</A></LI>
+<UL>
+<LI><A href="
+ #4.10.3.1">4.10.3.1 The calloc function</A></LI><LI><A href="
+ #4.10.3.2">4.10.3.2 The free function</A></LI><LI><A href="
+ #4.10.3.3">4.10.3.3 The malloc function</A></LI><LI><A href="
+ #4.10.3.4">4.10.3.4 The realloc function</A></LI></UL><LI><A href="
+ #4.10.4">4.10.4 Communication with the environment</A></LI>
+<UL>
+<LI><A href="
+ #4.10.4.1">4.10.4.1 The abort function</A></LI><LI><A href="
+ #4.10.4.2">4.10.4.2 The atexit function</A></LI><LI><A href="
+ #4.10.4.3">4.10.4.3 The exit function</A></LI><LI><A href="
+ #4.10.4.4">4.10.4.4 The getenv function</A></LI><LI><A href="
+ #4.10.4.5">4.10.4.5 The system function</A></LI></UL><LI><A href="
+ #4.10.5">4.10.5 Searching and sorting utilities</A></LI>
+<UL>
+<LI><A href="
+ #4.10.5.1">4.10.5.1 The bsearch function</A></LI><LI><A href="
+ #4.10.5.2">4.10.5.2 The qsort function</A></LI></UL><LI><A href="
+ #4.10.6">4.10.6 Integer arithmetic functions</A></LI>
+<UL>
+<LI><A href="
+ #4.10.6.1">4.10.6.1 The abs function</A></LI><LI><A href="
+ #4.10.6.2">4.10.6.2 The div function</A></LI><LI><A href="
+ #4.10.6.3">4.10.6.3 The labs function</A></LI><LI><A href="
+ #4.10.6.4">4.10.6.4 The ldiv function</A></LI></UL><LI><A href="
+ #4.10.7">4.10.7 Multibyte character functions</A></LI>
+<UL>
+<LI><A href="
+ #4.10.7.1">4.10.7.1 The mblen function</A></LI><LI><A href="
+ #4.10.7.2">4.10.7.2 The mbtowc function</A></LI><LI><A href="
+ #4.10.7.3">4.10.7.3 The wctomb function</A></LI></UL><LI><A href="
+ #4.10.8">4.10.8 Multibyte string functions</A></LI>
+<UL>
+<LI><A href="
+ #4.10.8.1">4.10.8.1 The mbstowcs function</A></LI><LI><A href="
+ #4.10.8.2">4.10.8.2 The wcstombs function</A></LI></UL></UL><LI><A href="
+ #4.11">4.11 STRING HANDLING <string.h></A></LI>
+<UL>
+<LI><A href="
+ #4.11.1">4.11.1 String function conventions</A></LI>
+<UL>
+</UL><LI><A href="
+ #4.11.2">4.11.2 Copying functions</A></LI>
+<UL>
+<LI><A href="
+ #4.11.2.1">4.11.2.1 The memcpy function</A></LI><LI><A href="
+ #4.11.2.2">4.11.2.2 The memmove function</A></LI><LI><A href="
+ #4.11.2.3">4.11.2.3 The strcpy function</A></LI><LI><A href="
+ #4.11.2.4">4.11.2.4 The strncpy function</A></LI></UL><LI><A href="
+ #4.11.3">4.11.3 Concatenation functions</A></LI>
+<UL>
+<LI><A href="
+ #4.11.3.1">4.11.3.1 The strcat function</A></LI><LI><A href="
+ #4.11.3.2">4.11.3.2 The strncat function</A></LI></UL><LI><A href="
+ #4.11.4">4.11.4 Comparison functions</A></LI>
+<UL>
+<LI><A href="
+ #4.11.4.1">4.11.4.1 The memcmp function</A></LI><LI><A href="
+ #4.11.4.2">4.11.4.2 The strcmp function</A></LI><LI><A href="
+ #4.11.4.3">4.11.4.3 The strcoll function</A></LI><LI><A href="
+ #4.11.4.4">4.11.4.4 The strncmp function</A></LI><LI><A href="
+ #4.11.4.5">4.11.4.5 The strxfrm function</A></LI></UL><LI><A href="
+ #4.11.5">4.11.5 Search functions</A></LI>
+<UL>
+<LI><A href="
+ #4.11.5.1">4.11.5.1 The memchr function</A></LI><LI><A href="
+ #4.11.5.2">4.11.5.2 The strchr function</A></LI><LI><A href="
+ #4.11.5.3">4.11.5.3 The strcspn function</A></LI><LI><A href="
+ #4.11.5.4">4.11.5.4 The strpbrk function</A></LI><LI><A href="
+ #4.11.5.5">4.11.5.5 The strrchr function</A></LI><LI><A href="
+ #4.11.5.6">4.11.5.6 The strspn function</A></LI><LI><A href="
+ #4.11.5.7">4.11.5.7 The strstr function</A></LI><LI><A href="
+ #4.11.5.8">4.11.5.8 The strtok function</A></LI></UL><LI><A href="
+ #4.11.6">4.11.6 Miscellaneous functions</A></LI>
+<UL>
+<LI><A href="
+ #4.11.6.1">4.11.6.1 The memset function</A></LI><LI><A href="
+ #4.11.6.2">4.11.6.2 The strerror function</A></LI><LI><A href="
+ #4.11.6.3">4.11.6.3 The strlen function</A></LI></UL></UL><LI><A href="
+ #4.12">4.12 DATE AND TIME <time.h></A></LI>
+<UL>
+<LI><A href="
+ #4.12.1">4.12.1 Components of time</A></LI>
+<UL>
+</UL><LI><A href="
+ #4.12.2">4.12.2 Time manipulation functions</A></LI>
+<UL>
+<LI><A href="
+ #4.12.2.1">4.12.2.1 The clock function</A></LI><LI><A href="
+ #4.12.2.2">4.12.2.2 The difftime function</A></LI><LI><A href="
+ #4.12.2.3">4.12.2.3 The mktime function</A></LI><LI><A href="
+ #4.12.2.4">4.12.2.4 The time function</A></LI></UL><LI><A href="
+ #4.12.3">4.12.3 Time conversion functions</A></LI>
+<UL>
+<LI><A href="
+ #4.12.3.1">4.12.3.1 The asctime function</A></LI><LI><A href="
+ #4.12.3.2">4.12.3.2 The ctime function</A></LI><LI><A href="
+ #4.12.3.3">4.12.3.3 The gmtime function</A></LI><LI><A href="
+ #4.12.3.4">4.12.3.4 The localtime function</A></LI><LI><A href="
+ #4.12.3.5">4.12.3.5 The strftime function</A></LI></UL></UL><LI><A href="
+ #4.13">4.13 FUTURE LIBRARY DIRECTIONS</A></LI>
+<UL>
+<LI><A href="
+ #4.13.1">4.13.1 Errors <errno.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.13.2">4.13.2 Character handling <ctype.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.13.3">4.13.3 Localization <locale.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.13.4">4.13.4 Mathematics <math.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.13.5">4.13.5 Signal handling <signal.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.13.6">4.13.6 Input/output <stdio.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.13.7">4.13.7 General utilities <stdlib.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #4.13.8">4.13.8 String handling <string.h></A></LI>
+<UL>
+</UL></UL></UL><LI><A href="
+ #A.">A. APPENDICES</A></LI>
+<UL>
+<LI><A href="
+ #A.1">A.1 LANGUAGE SYNTAX SUMMARY</A></LI>
+<UL>
+<LI><A href="
+ #A.1.1">A.1.1 Lexical grammar</A></LI>
+<UL>
+<LI><A href="
+ #A.1.1.1">A.1.1.1 Tokens</A></LI><LI><A href="
+ #A.1.1.2">A.1.1.2 Keywords</A></LI><LI><A href="
+ #A.1.1.3">A.1.1.3 Identifiers</A></LI><LI><A href="
+ #A.1.1.4">A.1.1.4 Constants</A></LI><LI><A href="
+ #A.1.1.5">A.1.1.5 String literals</A></LI><LI><A href="
+ #A.1.1.6">A.1.1.6 Operators</A></LI><LI><A href="
+ #A.1.1.7">A.1.1.7 Punctuators</A></LI><LI><A href="
+ #A.1.1.8">A.1.1.8 Header names</A></LI><LI><A href="
+ #A.1.1.9">A.1.1.9 Preprocessing numbers</A></LI></UL><LI><A href="
+ #A.1.2">A.1.2 Phrase structure grammar</A></LI>
+<UL>
+<LI><A href="
+ #A.1.2.1">A.1.2.1 Expressions</A></LI><LI><A href="
+ #A.1.2.2">A.1.2.2 Declarations</A></LI><LI><A href="
+ #A.1.2.3">A.1.2.3 Statements</A></LI><LI><A href="
+ #A.1.2.4">A.1.2.4 External definitions</A></LI></UL><LI><A href="
+ #A.1.3">A.1.3 Preprocessing directives</A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #A.2">A.2 SEQUENCE POINTS</A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3">A.3 LIBRARY SUMMARY</A></LI>
+<UL>
+<LI><A href="
+ #A.3.1">A.3.1 ERRORS <errno.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.2">A.3.2 COMMON DEFINITIONS <stddef.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.3">A.3.3 DIAGNOSTICS <assert.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.4">A.3.4 CHARACTER HANDLING <ctype.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.5">A.3.5 LOCALIZATION <locale.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.6">A.3.6 MATHEMATICS <math.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.7">A.3.7 NON-LOCAL JUMPS <setjmp.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.8">A.3.8 SIGNAL HANDLING <signal.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.9">A.3.9 VARIABLE ARGUMENTS <stdarg.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.10">A.3.10 INPUT/OUTPUT <stdio.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.11">A.3.11 GENERAL UTILITIES <stdlib.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.12">A.3.12 STRING HANDLING <string.h></A></LI>
+<UL>
+</UL><LI><A href="
+ #A.3.13">A.3.13 DATE AND TIME <time.h></A></LI>
+<UL>
+</UL></UL><LI><A href="
+ #A.4">A.4 IMPLEMENTATION LIMITS</A></LI>
+<UL>
+</UL><LI><A href="
+ #A.5">A.5 COMMON WARNINGS</A></LI>
+<UL>
+</UL><LI><A href="
+ #A.6">A.6 PORTABILITY ISSUES</A></LI>
+<UL>
+<LI><A href="
+ #A.6.1">A.6.1 Unspecified behavior</A></LI>
+<UL>
+</UL><LI><A href="
+ #A.6.2">A.6.2 Undefined behavior</A></LI>
+<UL>
+</UL><LI><A href="
+ #A.6.3">A.6.3 Implementation-defined behavior</A></LI>
+<UL>
+<LI><A href="
+ #A.6.3.1">A.6.3.1 Environment</A></LI><LI><A href="
+ #A.6.3.2">A.6.3.2 Identifiers</A></LI><LI><A href="
+ #A.6.3.3">A.6.3.3 Characters</A></LI><LI><A href="
+ #A.6.3.4">A.6.3.4 Integers</A></LI><LI><A href="
+ #A.6.3.5">A.6.3.5 Floating point</A></LI><LI><A href="
+ #A.6.3.6">A.6.3.6 Arrays and pointers</A></LI><LI><A href="
+ #A.6.3.7">A.6.3.7 Registers</A></LI><LI><A href="
+ #A.6.3.8">A.6.3.8 Structures, unions, enumerations, and bit-fields</A></LI><LI><A href="
+ #A.6.3.9">A.6.3.9 Qualifiers</A></LI><LI><A href="
+ #A.6.3.10">A.6.3.10 Declarators</A></LI><LI><A href="
+ #A.6.3.11">A.6.3.11 Statements</A></LI><LI><A href="
+ #A.6.3.12">A.6.3.12 Preprocessing directives</A></LI><LI><A href="
+ #A.6.3.13">A.6.3.13 Library functions</A></LI></UL><LI><A href="
+ #A.6.4">A.6.4 Locale-specific Behavior</A></LI>
+<UL>
+</UL><LI><A href="
+ #A.6.5">A.6.5 Common extensions</A></LI>
+<UL>
+<LI><A href="
+ #A.6.5.1">A.6.5.1 Environment arguments</A></LI><LI><A href="
+ #A.6.5.2">A.6.5.2 Specialized identifiers</A></LI><LI><A href="
+ #A.6.5.3">A.6.5.3 Lengths and cases of identifiers</A></LI><LI><A href="
+ #A.6.5.4">A.6.5.4 Scopes of identifiers</A></LI><LI><A href="
+ #A.6.5.5">A.6.5.5 Writable string literals</A></LI><LI><A href="
+ #A.6.5.6">A.6.5.6 Other arithmetic types</A></LI><LI><A href="
+ #A.6.5.7">A.6.5.7 Function pointer casts</A></LI><LI><A href="
+ #A.6.5.8">A.6.5.8 Non-int bit-field types</A></LI><LI><A href="
+ #A.6.5.9">A.6.5.9 The fortran keyword</A></LI><LI><A href="
+ #A.6.5.10">A.6.5.10 The asm keyword</A></LI><LI><A href="
+ #A.6.5.11">A.6.5.11 Multiple external definitions</A></LI><LI><A href="
+ #A.6.5.12">A.6.5.12 Empty macro arguments</A></LI><LI><A href="
+ #A.6.5.13">A.6.5.13 Predefined macro names</A></LI><LI><A href="
+ #A.6.5.14">A.6.5.14 Extra arguments for signal handlers</A></LI><LI><A href="
+ #A.6.5.15">A.6.5.15 Additional stream types and file-opening modes</A></LI><LI><A href="
+ #A.6.5.16">A.6.5.16 Defined file position indicator</A></LI></UL></UL><LI><A href="
+ #A.7">A.7 INDEX</A></LI>
+<UL>
+</UL></UL></UL></FONT>
+<P>
+<FONT size="-1">(This foreword is not a part of American National Standard for
+Information Systems --- Programming Language C, X3.???-1988.)
+</FONT></P><P>
+<FONT size="-1"> American National Standard Programming Language C specifies the
+syntax and semantics of programs written in the C programming
+language. It specifies the C program's interactions with the
+execution environment via input and output data. It also specifies
+restrictions and limits imposed upon conforming implementations of C
+language translators.
+</FONT></P><P>
+<FONT size="-1"> The standard was developed by the X3J11 Technical Committee on the
+C Programming Language under project 381-D by American National
+Standards Committee on Computers and Information Processing (X3).
+SPARC document number 83-079 describes the purpose of this project to
+``provide an unambiguous and machine-independent definition of the
+language C.''
+</FONT></P><P>
+<FONT size="-1"> The need for a single clearly defined standard had arisen in the C
+community due to a rapidly expanding use of the C programming language
+and the variety of differing translator implementations that had been
+and were being developed. The existence of similar but incompatible
+implementations was a serious problem for program developers who
+wished to develop code that would compile and execute as expected in
+several different environments.
+</FONT></P><P>
+<FONT size="-1"> Part of this problem could be traced to the fact that implementors
+did not have an adequate definition of the C language upon which to
+base their implementations. The de facto C programming language
+standard, The C Programming Language by Brian W. Kernighan and Dennis
+M. Ritchie, is an excellent book; however, it is not precise or
+complete enough to specify the C language fully. In addition, the
+language has grown over years of use to incorporate new ideas in
+programming and to address some of the weaknesses of the original
+language.
+</FONT></P><P>
+<FONT size="-1"> American National Standard Programming Language C addresses the
+problems of both the program developer and the translator implementor
+by specifying the C language precisely.
+</FONT></P><P>
+<FONT size="-1"> The work of X3J11 began in the summer of 1983, based on the several
+documents that were made available to the Committee (see <A href="
+ #1.5">1.5</A>, Base
+Documents). The Committee divided the effort into three pieces: the
+environment, the language, and the library. A complete specification
+in each of these areas is necessary if truly portable programs are to
+be developed. Each of these areas is addressed in the Standard. The
+Committee evaluated many proposals for additions, deletions, and
+changes to the base documents during its deliberations. A concerted
+effort was made to codify existing practice wherever unambiguous and
+consistent practice could be identified. However, where no consistent
+practice could be identified, the Committee worked to establish clear
+rules that were consistent with the overall flavor of the language.
+</FONT></P><P>
+<FONT size="-1"> This document was approved as an American National Standard by the
+American National Standards Institute (ANSI) on DD MM, 1988.
+Suggestions for improvement of this Standard are welcome. They should
+be sent to the American National Standards Institute, 1430 Broadway,
+New York, NY 10018.
+</FONT></P><P>
+<FONT size="-1"> The Standard was processed and approved for submittal to ANSI by
+the American National Standards Committee on Computers and Information
+Processing, X3. Committee approval of the Standard does not
+necessarily imply that all members voted for its approval. At the
+time that it approved this Standard, the X3 Committee had the
+following members:
+</FONT></P><P>
+<FONT size="-1"> Organization Name of Representative
+(To be completed on approval of the Standard.)
+</FONT></P><P>
+<FONT size="-1"> Technical Committee X3J11 on the C Programming Language had the
+following members at the time they forwarded this document to X3 for
+processing as an American National Standard:
+</FONT></P><P>
+<FONT size="-1">Chair
+Jim Brodie
+</FONT></P><P>
+<FONT size="-1">Vice-Chair
+Thomas Plum Plum Hall Secretary
+P. J. Plauger Whitesmiths, Ltd.
+</FONT></P><P>
+<FONT size="-1">International Representative
+P. J. Plauger Whitesmiths, Ltd.
+Steve Hersee Lattice, Inc.
+</FONT></P><P>
+<FONT size="-1">Vocabulary Representative
+Andrew Johnson Prime Computer
+</FONT></P><P>
+<FONT size="-1">Environment Subcommittee Chairs
+Ralph Ryan Microsoft
+Ralph Phraner Phraner Associates
+</FONT></P><P>
+<FONT size="-1">Language Subcommittee Chair
+Lawrence Rosler AT&T
+</FONT></P><P>
+<FONT size="-1">Library Subcommittee Chair
+P. J. Plauger Whitesmiths, Ltd.
+</FONT></P><P>
+<FONT size="-1">Draft Redactor
+David F. Prosser AT&T
+Lawrence Rosler AT&T
+</FONT></P><P>
+<FONT size="-1">Rationale Redactor
+Randy Hudson Intermetrics, Inc.
+</FONT></P><P>
+<FONT size="-1">In the following list, unmarked names denote principal members and *
+denotes alternate members.
+</FONT></P><P>
+<FONT size="-1">David F. Prosser, AT&T
+Steven J. Adamski, AT&T* (X3H2 SQL liaison)
+Bob Gottlieb, Alliant Computer Systems
+Kevin Brosnan, Alliant Computer Systems
+Neal Weidenhofer, Amdahl
+Philip C. Steel, American Cimflex
+Eric McGlohon, American Cimflex*
+Stephen Kafka, Analog Devices
+Kevin Leary, Analog Devices*
+Gordon Sterling, Analog Devices*
+John Peyton, Apollo Computer
+Elizabeth Crockett, Apple Computers
+Ed Wells, Arinc
+Tom Ketterhagen, Arinc*
+Vaughn Vernon, Aspen Scientific
+Craig Bordelon, Bell Communications Research
+Steve Carter, Bell Communications Research*
+William Puig, Bell Communications Research*
+Bob Jervis, Borland International
+Yom-Tov Meged, Boston Systems Office
+Rose Thomson, Boston Systems Office*
+Maurice Fathi, COSMIC
+John Wu, Charles River Data Systems
+Daniel Mickey, Chemical Abstracts Service
+Thomas Mimlitch, Chemical Abstracts Service*
+Alan Losoff, Chicago Research & Trading Group
+Edward Briggs, Citibank
+Firmo Freire, Cobra S/A
+Jim Patterson, Cognos
+Bruce Tetelman, Columbia U. Center for Computing
+Terry Moore, CompuDas
+Mark Barrenechea, Computer Associates
+George Eberhardt, Computer Innovations
+Dave Neathery, Computer Innovations*
+Joseph Bibbo, Computrition
+Steve Davies, Concurrent Computer Corporation
+Don Fosbury, Control Data
+George VandeBunte, Control Data*
+Lloyd Irons, Cormorant Communications
+Tom MacDonald, Cray Research
+Lynne Johnson, Cray Research*
+Dave Becker, Cray Research*
+Jean Risley, Custom Development Environments
+Rex Jaeschke, DEC Professional
+Mike Terrazas, DECUS Representative
+Michael Meissner, Data General
+Mark Harris, Data General*
+Leonard Ohmes, Datapoint
+James Stanley, Data Systems Analysts
+Samuel J. Kendall, Delft Consulting
+Randy Meyers, Digital Equipment Corporation
+Art Bjork, Digital Equipment Corporation*
+Lu Anne Van de Pas, Digital Equipment Corporation*
+Ben Patel, EDS
+Richard Relph, EPI
+Graham Andrews, Edinburgh Portable Compilers
+Colin McPhail, Edinburgh Portable Compilers*
+J. Stephen Adamczyk, Edison Design Group
+Eric Schwarz, Edison Design Group*
+Dmitry Lenkov, Everest Solutions
+Frank Farance, Farance Inc.
+Peter Hayes, Farance Inc.*
+Florin Jordan, Floradin
+Philip Provin, General Electric Information Services
+Liz Sanville, Gould CSD
+Tina Aleksa, Gould CSD*
+Thomas Kelly, HCR Corporation
+Paul Jackson, HCR Corporation*
+Gary Jeter, Harris Computer Systems
+Sue Meloy, Hewlett Packard
+Larry Rosler, Hewlett Packard*
+Michelle Ruscetta, Hewlett Packard*
+Thomas E. Osten, Honeywell Information Systems
+David Kayden, Honeywell Information Systems*
+Shawn Elliott, IBM
+Larry Breed, IBM*
+Mel Goldberg, IBM*
+Mike Banahan, Instruction Set
+Clark Nelson, Intel
+Dan Lau, Intel*
+John Wolfe, InterACT
+Lillian Toll, InterACT*
+Randy Hudson, Intermetrics
+Keith Winter, International Computers Ltd.
+Honey M. Schrecker, International Computers Ltd.*
+Jim Brodie, J. Brodie & Associates
+Jacklin Kotikian, Kendall Square Research
+W. Peter Hesse, LSI Logic Europe Ltd.
+John Kaminski, Language Processors Inc.
+David Yost, Laurel Arts
+Mike Branstetter, Lawrence Livermore National Laboratory
+Bob Weaver, Los Alamos National Laboratory
+Lidia Eberhart, Modcomp
+Robert Sherry, Manx Software
+Courtney Meissen, Mark Williams Co.
+Patricia Jenkins, Masscomp
+Dave Hinman, Masscomp*
+Michael Kearns, MetaLink
+Tom Pennello, MetaWare Incorporated
+David F. Weil, Microsoft
+Mitch Harder, Microsoft*
+Kim Kempf, Microware Systems
+Shane McCarron, Minnesota Educational Computing
+Bruce Olsen, Mosaic Technologies
+Michael Paton, Motorola
+Rick Schubert, NCR
+Brian Johnson, NCR*
+Joseph Mueller, National Semiconductor
+Derek Godfrey, National Semiconductor*
+Jim Upperman, National Bureau of Standards
+James W. Williams, Naval Research Laboratory
+Lisa Simon, OCLC
+Paul Amaranth, Oakland University
+August R. Hansen, Omniware
+Michael Rolle, Oracle
+Carl Ellis, Oregon Software
+Barry Hedquist, Perennial
+Sassan Hazeghi, Peritus International
+James Holmlund, Peritus International*
+Thomas Plum, Plum Hall
+Christopher Skelly, Plum Hall*
+Andrew Johnson, Prime Computer
+Fran Litterio, Prime Computer*
+Daniel J. Conrad, Prismatics
+David Fritz, Production Languages
+Kenneth Pugh, Pugh
+Killeen Ed Ramsey, Purdue University
+Stephen Roberts, Purdue University*
+Kevin Nolan, Quantitative Technology Corp.
+Robert Mueller, Quantitative Technology Corp.*
+Chris DeVoney, Que Corporation
+Jon Tulk, Rabbit Software
+Terry Colligan, Rational Systems
+Daniel Saks, Saks & Associates
+Nancy Saks, Saks & Associates*
+Oliver Bradley, SAS Institute
+Alan Beale, SAS Institute*
+Larry Jones, SDRC
+Donald Kossman, SEI Information Technology
+Kenneth Harrenstien, SRI International
+Larry Rosenthal, Sierra Systems
+Phil Hempfner, Southern Bell Telephone
+Purshotam Rajani, Spruce Technology
+Savu Savulescu, Stagg Systems
+Peter Darnell, Stellar Computer
+Lee W. Cooprider, Stellar Computer*
+Paul Gilmartin, Storage Technology Corp.
+Steve Muchnick, Sun Microsystems
+Chuck Rasbold, Supercomputer Systems, Inc.
+Kelly O'Hair, Supercomputer Systems, Inc.*
+Henry Richardson, Tandem
+John M. Hausman, Tandem*
+Samuel Harbison, Tartan Laboratories
+Michael S. Ball, TauMetric
+Carl Sutton, Tektronix
+Jim Besemer, Tektronix*
+Reid Tatge, Texas Instruments
+Ed Brower, Tokheim
+Robert Mansfield, Tokheim*
+Monika Khushf, Tymlabs
+Morgan Jones, Tymlabs*
+Don Bixler, Unisys
+Steve Bartels, Unisys*
+Glenda Berkheimer, Unisys*
+Annice Jackson, Unisys*
+Fred Blonder, University of Maryland
+Fred Schwarz, University of Michigan
+R. Jordan Kreindler, University of Southern California CTC
+Mike Carmody, University of Waterloo
+Douglas Gwyn, US Army BRL (IEEE P1003 liaison)
+C. Dale Pierce, US Army Management Engineering*
+John C. Black, VideoFinancial
+Joseph Musacchia, Wang Labs
+Fred Rozakis, Wang Labs*
+P. J. Plauger, Whitesmiths, Ltd.
+Kim Leeper, Wick Hill
+Mark Wittenberg, Zehntel
+Jim Balter
+Robert Bradbury
+Edward Chin
+Neil Daniels
+Stephen Desofi
+Michael Duffy
+Phillip Escue
+Ralph Phraner
+D. Hugh Redelmeier
+Arnold Davi
+Robbins Roger
+Wilks Michael
+J. Young
+</FONT></P><P>
+<FONT size="-1">purpose: 1.1
+scope: 1.2
+references: 1.3
+organization of the document: 1.4
+base documents: 1.5
+definitions of terms: 1.6
+compliance: 1.7
+translation environment: 2.
+execution environment: 2.
+separate compilation: 2.1.1.1
+separate translation: 2.1.1.1
+source file: 2.1.1.1
+translation unit: 2.1.1.1
+program execution: 2.1.2.3
+side effects: 2.1.2.3
+sequence point: 2.1.2.3
+character set: 2.2.1
+signals: 2.2.3
+interrupts: 2.2.3
+syntax notation: 3.
+lexical elements: 3.1
+comment: 3.1
+white space: 3.1
+list of keywords: 3.1.1
+reserved words: 3.1.1
+underscore character: 3.1.2
+enumeration constant: 3.1.2
+length of names: 3.1.2
+internal name, length of: 3.1.2
+external name, length of: 3.1.2
+function name, length of: 3.1.2
+scopes: 3.1.2.1
+prototype, function: 3.1.2.1
+function scope: 3.1.2.1
+file scope: 3.1.2.1
+block scope: 3.1.2.1
+block structure: 3.1.2.1
+function prototype scope: 3.1.2.1
+linkage: 3.1.2.2
+external linkage: 3.1.2.2
+internal linkage: 3.1.2.2
+no linkage: 3.1.2.2
+name spaces: 3.1.2.3
+named label: 3.1.2.3
+structure tag: 3.1.2.3
+union tag: 3.1.2.3
+enumeration tag: 3.1.2.3
+structure member name: 3.1.2.3
+union member name: 3.1.2.3
+storage duration: 3.1.2.4
+static storage duration: 3.1.2.4
+automatic storage duration: 3.1.2.4
+types: 3.1.2.5
+object types: 3.1.2.5
+function types: 3.1.2.5
+incomplete types: 3.1.2.5
+char type: 3.1.2.5
+signed character: 3.1.2.5
+signed char type: 3.1.2.5
+short type: 3.1.2.5
+long type: 3.1.2.5
+unsigned type: 3.1.2.5
+float type: 3.1.2.5
+double type: 3.1.2.5
+long double type: 3.1.2.5
+basic types: 3.1.2.5
+character types: 3.1.2.5
+enumerated type: 3.1.2.5
+void type: 3.1.2.5
+derived types: 3.1.2.5
+integral types: 3.1.2.5
+arithmetic types: 3.1.2.5
+scalar types: 3.1.2.5
+aggregate types: 3.1.2.5
+constants: 3.1.3
+floating constant: 3.1.3.1
+double constant: 3.1.3.1
+integer constant: 3.1.3.2
+decimal constant: 3.1.3.2
+octal constant: 3.1.3.2
+hexadecimal constant: 3.1.3.2
+unsigned constant: 3.1.3.2
+long constant: 3.1.3.2
+enumeration constant: 3.1.3.3
+character constant: 3.1.3.4
+backslash character: 3.1.3.4
+escape character: 3.1.3.4
+escape sequence: 3.1.3.4
+string literal: 3.1.4
+character string: 3.1.4
+operator: 3.1.5
+evaluation: 3.1.5
+operand: 3.1.5
+punctuator: 3.1.6
+character-integer conversion: 3.2.1.1
+integer-character conversion: 3.2.1.1
+integral promotions: 3.2.1.1
+integer-long conversion: 3.2.1.1
+signed character: 3.2.1.1
+unsigned-integer conversion: 3.2.1.2
+integer-unsigned conversion: 3.2.1.2
+long-unsigned conversion: 3.2.1.2
+long-integer conversion: 3.2.1.2
+floating-integer conversion: 3.2.1.3
+integer-floating conversion: 3.2.1.3
+float-double conversion: 3.2.1.4
+double-float conversion: 3.2.1.4
+arithmetic conversions: 3.2.1.5
+type conversion rules: 3.2.1.5
+lvalue: 3.2.2.1
+function designator: 3.2.2.1
+conversion of array: 3.2.2.1
+conversion of function name: 3.2.2.1
+void type: 3.2.2.2
+pointer-pointer conversion: 3.2.2.3
+integer-pointer conversion: 3.2.2.3
+null pointer: 3.2.2.3
+expression: 3.3
+precedence of operators: 3.3
+associativity of operators: 3.3
+order of evaluation of expressions: 3.3
+order of evaluation: 3.3
+bitwise operators: 3.3
+exceptions: 3.3
+primary expression: 3.3.1
+type of string: 3.3.1
+parenthesized expression: 3.3.1
+subscript operator: 3.3.2
+function call: 3.3.2
+structure member operator: 3.3.2
+structure pointer operator: 3.3.2
+++ increment operator: 3.3.2
+-- decrement operator: 3.3.2
+array, explanation of subscripting: 3.3.2.1
+subscripting, explanation of: 3.3.2.1
+multi-dimensional array: 3.3.2.1
+storage order of array: 3.3.2.1
+function call: 3.3.2.2
+implicit declaration of function: 3.3.2.2
+function argument: 3.3.2.2
+call by value: 3.3.2.2
+recursion: 3.3.2.2
+structure reference: 3.3.2.3
+union reference: 3.3.2.3
+common initial sequence: 3.3.2.3
+postfix ++ and --: 3.3.2.4
+-- decrement operator: 3.3.2.4
+unary expression: 3.3.3
+++ increment operator: 3.3.3
+-- decrement operator: 3.3.3
+sizeof operator: 3.3.3
+& address operator: 3.3.3
+* indirection operator: 3.3.3
++ unary plus operator: 3.3.3
+- unary minus operator: 3.3.3
+~ bitwise complement operator: 3.3.3
+! logical negation operator: 3.3.3
+++ increment operator: 3.3.3.1
+prefix ++ and --: 3.3.3.1
+-- decrement operator: 3.3.3.1
++ unary plus operator: 3.3.3.3
+- unary minus operator: 3.3.3.3
+~ bitwise complement operator: 3.3.3.3
+! logical negation operator: 3.3.3.3
+byte: 3.3.3.4
+storage allocator: 3.3.3.4
+cast expression: 3.3.4
+cast operator: 3.3.4
+explicit conversion operator: 3.3.4
+cast operator: 3.3.4
+pointer conversion: 3.3.4
+explicit conversion operator: 3.3.4
+pointer-integer conversion: 3.3.4
+integer-pointer conversion: 3.3.4
+alignment restriction: 3.3.4
+arithmetic operators: 3.3.5
+multiplicative operators: 3.3.5
+* multiplication operator: 3.3.5
+/ division operator: 3.3.5
+% modulus operator: 3.3.5
+additive operators: 3.3.6
++ addition operator: 3.3.6
+- subtraction operator: 3.3.6
+pointer arithmetic: 3.3.6
+pointer arithmetic: 3.3.6
+shift operators: 3.3.7
+<< left shift operator: 3.3.7
+>> right shift operator: 3.3.7
+relational operators: 3.3.8
+< less than operator: 3.3.8
+> greater than operator: 3.3.8
+<= less than or equal to operator: 3.3.8
+>= greater than or equal to operator: 3.3.8
+pointer comparison: 3.3.8
+equality operators: 3.3.9
+== equality operator: 3.3.9
+!= inequality operator: 3.3.9
+& bitwise AND operator: 3.3.10
+^ bitwise exclusive OR operator: 3.3.11
+| bitwise inclusive OR operator: 3.3.12
+&& logical AND operator: 3.3.13
+|| logical OR operator: 3.3.14
+?: conditional expression: 3.3.15
+assignment operators: 3.3.16
+assignment expression: 3.3.16
+simple assignment: 3.3.16.1
+conversion by assignment: 3.3.16.1
+compound assignment: 3.3.16.2
+comma operator: 3.3.17
+constant expression: 3.4
+permitted form of initializer: 3.4
+declarations: 3.5
+storage-class specifier: 3.5.1
+storage-class declaration: 3.5.1
+typedef declaration: 3.5.1
+extern storage class: 3.5.1
+static storage class: 3.5.1
+auto storage class: 3.5.1
+register storage class: 3.5.1
+type specifier: 3.5.2
+void type: 3.5.2
+char type: 3.5.2
+short type: 3.5.2
+int type: 3.5.2
+long type: 3.5.2
+float type: 3.5.2
+double type: 3.5.2
+signed type: 3.5.2
+unsigned type: 3.5.2
+structure declaration: 3.5.2.1
+union declaration: 3.5.2.1
+bit-field declaration: 3.5.2.1
+bit-field: 3.5.2.1
+member alignment: 3.5.2.1
+enumeration: 3.5.2.2
+enum-specifier: 3.5.2.2
+enumerator: 3.5.2.2
+structure tag: 3.5.2.3
+union tag: 3.5.2.3
+structure content: 3.5.2.3
+union content: 3.5.2.3
+enumeration content: 3.5.2.3
+self-referential structure: 3.5.2.3
+type qualifier: 3.5.3
+const type qualifier: 3.5.3
+volatile type qualifier: 3.5.3
+declarator: 3.5.4
+type declaration: 3.5.4
+declaration of pointer: 3.5.4.1
+array declaration: 3.5.4.2
+declaration of function: 3.5.4.3
+type names: 3.5.5
+abstract declarator: 3.5.5
+typedef declaration: 3.5.6
+initialization: 3.5.7
+initialization of statics: 3.5.7
+implicit initialization: 3.5.7
+default initialization: 3.5.7
+initialization of automatics: 3.5.7
+aggregate initialization: 3.5.7
+array initialization: 3.5.7
+structure initialization: 3.5.7
+character array initialization: 3.5.7
+wchar_t array initialization: 3.5.7
+statements: 3.6
+sequencing of statements: 3.6
+full expression: 3.6
+labeled statement: 3.6.1
+named label: 3.6.1
+case label: 3.6.1
+default label: 3.6.1
+compound statement: 3.6.2
+block: 3.6.2
+block structure: 3.6.2
+initialization in blocks: 3.6.2
+expression statement: 3.6.3
+null statement: 3.6.3
+empty statement: 3.6.3
+if-else statement: 3.6.4.1
+switch statement: 3.6.4.2
+switch body: 3.6.4.2
+loop body: 3.6.5
+while statement: 3.6.5.1
+do statement: 3.6.5.2
+for statement: 3.6.5.3
+goto statement: 3.6.6.1
+continue statement: 3.6.6.2
+break statement: 3.6.6.3
+return statement: 3.6.6.4
+type conversion by return: 3.6.6.4
+conversion by return: 3.6.6.4
+external definition: 3.7
+function definition: 3.7.1
+parameter: 3.7.1
+array argument: 3.7.1
+function name argument: 3.7.1
+pointer to function: 3.7.1
+object definitions: 3.7.2
+scope of externals: 3.7.2
+tentative definition: 3.7.2
+preprocessing directives: 3.8
+macro preprocessor: 3.8
+preprocessing directive lines: 3.8
+conditional inclusion: 3.8.1
+#if: 3.8.1
+#elif 3.8.1
+#ifdef: 3.8.1
+#ifndef: 3.8.1
+#else: 3.8.1
+#endif: 3.8.1
+#include: 3.8.2
+source file inclusion: 3.8.2
+macro replacement: 3.8.3
+object-like macro: 3.8.3
+function-like macro: 3.8.3
+macro name: 3.8.3
+#define: 3.8.3
+macro parameters: 3.8.3
+macro invocation: 3.8.3
+argument substitution: 3.8.3.1
+# operator: 3.8.3.2
+## operator: 3.8.3.3
+rescanning and replacement: 3.8.3.4
+macro definition scope: 3.8.3.5
+#undef: 3.8.3.5
+#line: 3.8.4
+error directive: 3.8.5
+pragma directive: 3.8.6
+null directive: 3.8.7
+introduction: 4.1
+string definition: 4.1.1
+letter definition: 4.1.1
+decimal-point definition: 4.1.1
+reserved identifier: 4.1.2
+printing character: 4.3
+control character: 4.3
+variable arguments: 4.8
+unbuffered stream: 4.9.3
+fully buffered stream: 4.9.3
+line buffered stream: 4.9.3
+appendices: A.
+language syntax summary: A.1
+sequence points: A.2
+library summary: A.3
+implementation limits: A.4
+warnings: A.5
+portability: A.6
+order of evaluation: A.6.1
+machine dependency: A.6.3
+restrictions on registers: A.6.3.7
+function pointer casts: A.6.5.7
+bit-field types: A.6.5.8
+fortran keyword: A.6.5.9
+asm keyword: A.6.5.10
+multiple external definitions: A.6.5.11
+empty macro arguments: A.6.5.12
+predefined macro names: A.6.5.13
+signal handler arguments: A.6.5.14
+stream types: A.6.5.15
+file-opening modes: A.6.5.15
+file position indicator: A.6.5.16
+foreword: A.7
+</FONT></P><H2><A name="1.">1. INTRODUCTION</A></H2>
+<H3><A name="1.1">1.1 PURPOSE</A></H3>
+<P>
+<FONT size="-1"> This Standard specifies the form and establishes the interpretation
+ of programs written in the C programming language.<SUP><A href="
+ #1">1</A></SUP></FONT></P><H3><A name="1.2">1.2 SCOPE</A></H3>
+<P>
+<FONT size="-1"> This Standard specifies:
+</FONT></P><P>
+<FONT size="-1"> * the representation of C programs;
+</FONT></P><P>
+<FONT size="-1"> * the syntax and constraints of the C language;
+</FONT></P><P>
+<FONT size="-1"> * the semantic rules for interpreting C programs;
+</FONT></P><P>
+<FONT size="-1"> * the representation of input data to be processed by C programs;
+</FONT></P><P>
+<FONT size="-1"> * the representation of output data produced by C programs;
+</FONT></P><P>
+<FONT size="-1"> * the restrictions and limits imposed by a conforming implementation of C.
+</FONT></P><P>
+<FONT size="-1"> This Standard does not specify:
+</FONT></P><P>
+<FONT size="-1"> * the mechanism by which C programs are transformed for use by a
+ data-processing system;
+</FONT></P><P>
+<FONT size="-1"> * the mechanism by which C programs are invoked for use by a
+ data-processing system;
+</FONT></P><P>
+<FONT size="-1"> * the mechanism by which input data are transformed for use by a C program;
+</FONT></P><P>
+<FONT size="-1"> * the mechanism by which output data are transformed after being
+ produced by a C program;
+</FONT></P><P>
+<FONT size="-1"> * the size or complexity of a program and its data that will exceed
+ the capacity of any specific data-processing system or the capacity of
+ a particular processor;
+</FONT></P><P>
+<FONT size="-1"> * all minimal requirements of a data-processing system that is
+ capable of supporting a conforming implementation.
+</FONT></P><H3><A name="1.3">1.3 REFERENCES</A></H3>
+<P>
+<FONT size="-1"> 1. ``The C Reference Manual'' by Dennis M. Ritchie, a version of
+ which was published in The C Programming Language by Brian
+ W. Kernighan and Dennis M. Ritchie, Prentice-Hall, Inc., (1978).
+ Copyright owned by AT&T.
+</FONT></P><P>
+<FONT size="-1"> 2. 1984 /usr/group Standard by the /usr/group Standards Committee,
+ Santa Clara, California, USA (November, 1984).
+</FONT></P><P>
+<FONT size="-1"> 3. American National Dictionary for Information Processing Systems,
+ Information Processing Systems Technical Report ANSI X3/TR-1-82 (1982).
+</FONT></P><P>
+<FONT size="-1"> 4. ISO 646-1983 Invariant Code Set.
+</FONT></P><P>
+<FONT size="-1"> 5. IEEE Standard for Binary Floating-Point Arithmetic (ANSI/IEEE Std 754-1985).
+</FONT></P><P>
+<FONT size="-1"> 6. ISO 4217 Codes for the Representation of Currency and Funds.
+</FONT></P><H3><A name="1.4">1.4 ORGANIZATION OF THE DOCUMENT</A></H3>
+<P>
+<FONT size="-1"> This document is divided into four major sections:
+</FONT></P><P>
+<FONT size="-1"> 1. this introduction;
+</FONT></P><P>
+<FONT size="-1"> 2. the characteristics of environments that translate and execute C programs;
+</FONT></P><P>
+<FONT size="-1"> 3. the language syntax, constraints, and semantics;
+</FONT></P><P>
+<FONT size="-1"> 4. the library facilities.
+</FONT></P><P>
+<FONT size="-1">Examples are provided to illustrate possible forms of the
+constructions described. Footnotes are provided to emphasize
+consequences of the rules described in the section or elsewhere in the
+Standard. References are used to refer to other related sections. A
+set of appendices summarizes information contained in the Standard.
+The abstract, the foreword, the examples, the footnotes, the
+references, and the appendices are not part of the Standard.
+</FONT></P><H3><A name="1.5">1.5 BASE DOCUMENTS</A></H3>
+<P>
+<FONT size="-1">The language section (<A href="
+ #3.">3.</A>) is derived from ``The C Reference
+Manual'' by Dennis M. Ritchie, a version of which was published as
+Appendix A of The C Programming Language by Brian W. Kernighan and
+Dennis M. Ritchie, Prentice-Hall, Inc., 1978; copyright owned by AT&T.
+</FONT></P><P>
+<FONT size="-1">The library section (<A href="
+ #4.">4.</A>) is based on the 1984 /usr/group Standard by
+the /usr/group Standards Committee, Santa Clara, California, USA
+(November 14, 1984).
+</FONT></P><H3><A name="1.6">1.6 DEFINITIONS OF TERMS</A></H3>
+<P>
+<FONT size="-1"> In this Standard, ``shall'' is to be interpreted as a requirement
+on an implementation or on a program; conversely, ``shall not'' is to
+be interpreted as a prohibition.
+</FONT></P><P>
+<FONT size="-1">The following terms are used in this document:
+</FONT></P><P>
+<FONT size="-1"> * Implementation --- a particular set of software, running in a
+ particular translation environment under particular control options,
+ that performs translation of programs for, and supports execution of
+ functions in, a particular execution environment.
+</FONT></P><P>
+<FONT size="-1"> * Bit --- the unit of data storage in the execution environment large
+ enough to hold an object that may have one of two values. It need not
+ be possible to express the address of each individual bit of an
+ object.
+</FONT></P><P>
+<FONT size="-1"> * Byte --- the unit of data storage in the execution environment
+ large enough to hold any member of the basic character set of the
+ execution environment. It shall be possible to express the address of
+ each individual byte of an object uniquely. A byte is composed of a
+ contiguous sequence of bits, the number of which is
+ implementation-defined. The least significant bit is called the
+ low-order bit; the most significant bit is called the high-order bit.
+</FONT></P><P>
+<FONT size="-1"> * Object --- a region of data storage in the execution environment,
+ the contents of which can represent values. Except for bit-fields,
+ objects are composed of contiguous sequences of one or more bytes, the
+ number, order, and encoding of which are either explicitly specified
+ or implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> * Character --- a single byte representing a member of the basic
+ character set of either the source or the execution environment.
+</FONT></P><P>
+<FONT size="-1"> * Multibyte character --- a sequence of one or more bytes
+ representing a member of the extended character set of either the
+ source or the execution environment. The extended character set is a
+ superset of the basic character set.
+</FONT></P><P>
+<FONT size="-1"> * Alignment --- a requirement that objects of a particular type be
+ located on storage boundaries with addresses that are particular
+ multiples of a byte address.
+</FONT></P><P>
+<FONT size="-1"> * Argument --- an expression in the comma-separated list bounded by
+ the parentheses in a function call expression, or a sequence of
+ preprocessing tokens in the comma-separated list bounded by the
+ parentheses in a function-like macro invocation. Also known as
+ ``actual argument'' or ``actual parameter.''
+</FONT></P><P>
+<FONT size="-1"> * Parameter --- an object declared as part of a function declaration
+ or definition that acquires a value on entry to the function, or an
+ identifier from the comma-separated list bounded by the parentheses
+ immediately following the macro name in a function-like macro
+ definition. Also known as ``formal argument'' or ``formal
+ parameter.''
+</FONT></P><P>
+<FONT size="-1"> * Unspecified behavior --- behavior, for a correct program construct
+ and correct data, for which the Standard imposes no requirements.
+</FONT></P><P>
+<FONT size="-1"> * Undefined behavior --- behavior, upon use of a nonportable or
+ erroneous program construct, of erroneous data, or of
+ indeterminately-valued objects, for which the Standard imposes no
+ requirements. Permissible undefined behavior ranges from ignoring the
+ situation completely with unpredictable results, to behaving during
+ translation or program execution in a documented manner characteristic
+ of the environment (with or without the issuance of a diagnostic
+ message), to terminating a translation or execution (with the issuance
+ of a diagnostic message).
+</FONT></P><P>
+<FONT size="-1"> If a ``shall'' or ``shall not'' requirement that appears outside of
+ a constraint is violated, the behavior is undefined. Undefined
+ behavior is otherwise indicated in this Standard by the words
+ ``undefined behavior'' or by the omission of any explicit definition
+ of behavior. There is no difference in emphasis among these three;
+ they all describe ``behavior that is undefined.''
+</FONT></P><P>
+<FONT size="-1"> * Implementation-defined behavior --- behavior, for a correct program
+ construct and correct data, that depends on the characteristics of the
+ implementation and that each implementation shall document.
+</FONT></P><P>
+<FONT size="-1"> * Locale-specific behavior --- behavior that depends on local
+ conventions of nationality, culture, and language that each
+ implementation shall document.
+</FONT></P><P>
+<FONT size="-1"> * Diagnostic message --- a message belonging to an
+ implementation-defined subset of the implementation's message output.
+</FONT></P><P>
+<FONT size="-1"> * Constraints --- syntactic and semantic restrictions by which the
+ exposition of language elements is to be interpreted.
+</FONT></P><P>
+<FONT size="-1"> * Implementation limits --- restrictions imposed upon programs by the
+ implementation.
+</FONT></P><P>
+<FONT size="-1"> * Forward references --- references to later sections of the Standard
+ that contain additional information relevant to this section.
+</FONT></P><P>
+<FONT size="-1"> Other terms are defined at their first appearance, indicated by italic
+ type. Terms explicitly defined in this Standard are not to be
+ presumed to refer implicitly to similar terms defined elsewhere.
+</FONT></P><P>
+<FONT size="-1"> Terms not defined in this Standard are to be interpreted according to
+ the American National Dictionary for Information Processing Systems,
+ Information Processing Systems Technical Report ANSI X3/TR-1-82 (1982).
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ localization (<A href="
+ #4.4">4.4</A>).
+<P>
+<FONT size="-1">"Examples"
+</FONT></P><P>
+<FONT size="-1"> An example of unspecified behavior is the order in which the
+ arguments to a function are evaluated.
+</FONT></P><P>
+<FONT size="-1"> An example of undefined behavior is the behavior on integer overflow.
+</FONT></P><P>
+<FONT size="-1"> An example of implementation-defined behavior is the propagation of
+ the high-order bit when a signed integer is shifted right.
+</FONT></P><P>
+<FONT size="-1"> An example of locale-specific behavior is whether the islower
+ function returns true for characters other than the 26 lower-case
+ English letters.
+</FONT></P></FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ bitwise shift operators (<A href="
+ #3.3.7">3.3.7</A>), expressions
+(<A href="
+ #3.3">3.3</A>), function calls (<A href="
+ #3.3.2.2">3.3.2.2</A>), the islower function (<A href="
+ #4.3.1.6">4.3.1.6</A>).
+</FONT></P><H3><A name="1.7">1.7 COMPLIANCE</A></H3>
+<P>
+<FONT size="-1"> A strictly conforming program shall use only those features of the
+language and library specified in this Standard. It shall not produce
+output dependent on any unspecified, undefined, or
+implementation-defined behavior, and shall not exceed any minimum
+implementation limit.
+</FONT></P><P>
+<FONT size="-1"> The two forms of conforming implementation are hosted and
+freestanding. A conforming hosted implementation shall accept any
+strictly conforming program. A conforming freestanding implementation
+shall accept any strictly conforming program in which the use of the
+features specified in the library section (<A href="
+ #4.">4.</A>) is confined to the
+contents of the standard headers <float.h> , <limits.h> , <stdarg.h> ,
+and <stddef.h> . A conforming implementation may have extensions
+(including additional library functions), provided they do not alter
+the behavior of any strictly conforming program.
+</FONT></P><P>
+<FONT size="-1"> A conforming program is one that is acceptable to a conforming
+implementation.<SUP><A href="
+ #2">2</A></SUP></FONT></P><P>
+<FONT size="-1"> An implementation shall be accompanied by a document that defines
+all implementation-defined characteristics and all extensions.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ limits <float.h> and <limits.h> (<A href="
+ #4.1.4">4.1.4</A>), variable
+arguments <stdarg.h> (<A href="
+ #4.8">4.8</A>), common definitions <stddef.h> (<A href="
+ #4.1.5">4.1.5</A>).
+</FONT></P><H3><A name="1.8">1.8 FUTURE DIRECTIONS</A></H3>
+<P>
+<FONT size="-1"> With the introduction of new devices and extended character sets,
+new features may be added to the Standard. Subsections in the
+language and library sections warn implementors and programmers of
+usages which, though valid in themselves, may conflict with future
+additions.
+</FONT></P><P>
+<FONT size="-1"> Certain features are obsolescent, which means that they may be
+considered for withdrawal in future revisions of the Standard. They
+are retained in the Standard because of their widespread use, but
+their use in new implementations (for implementation features) or new
+programs (for language or library features) is discouraged.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ future language directions (<A href="
+ #3.9.9">3.9.9</A>), future
+library directions (<A href="
+ #4.13">4.13</A>).
+</FONT></P><H3><A name="1.9">1.9 ABOUT THIS DRAFT</A></H3>
+<P>
+<FONT size="-1"> Symbols in the right margin mark substantive differences between
+this draft and its predecessor (ANSI X3J11/88-001, January 11, 1988).
+A plus sign indicates an addition, a minus sign a deletion, and a
+vertical bar a replacement.
+</FONT></P><P>
+<FONT size="-1"> This section and the difference marks themselves will not appear in
+the published document.
+</FONT></P><H2><A name="2.">2. ENVIRONMENT</A></H2>
+<P>
+<FONT size="-1"> An implementation translates C source files and executes C programs
+in two data-processing-system environments, which will be called the
+translation environment and the execution environment in this
+Standard. Their characteristics define and constrain the results of
+executing conforming C programs constructed according to the syntactic
+and semantic rules for conforming implementations.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ In the environment section (<A href="
+ #2.">2.</A>), only a few of
+many possible forward references have been noted.
+</FONT></P><H3><A name="2.1">2.1 CONCEPTUAL MODELS</A></H3>
+<H4><A name="2.1.1">2.1.1 Translation environment</A></H4>
+<H5><A name="2.1.1.1">2.1.1.1 Program structure</A></H5>
+<P>
+<FONT size="-1"> A C program need not all be translated at the same time. The text
+of the program is kept in units called source files in this Standard.
+A source file together with all the headers and source files included
+via the preprocessing directive #include , less any source lines
+skipped by any of the conditional inclusion preprocessing directives,
+is called a translation unit. Previously translated translation units
+may be preserved individually or in libraries. The separate
+translation units of a program communicate by (for example) calls to
+functions whose identifiers have external linkage, by manipulation of
+objects whose identifiers have external linkage, and by manipulation
+of data files. Translation units may be separately translated and
+then later linked to produce an executable program.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ conditional inclusion (<A href="
+ #3.8.1">3.8.1</A>), linkages of
+identifiers (<A href="
+ #3.1.2.2">3.1.2.2</A>), source file inclusion (<A href="
+ #3.8.2">3.8.2</A>).
+</FONT></P><H5><A name="2.1.1.2">2.1.1.2 Translation phases</A></H5>
+<P>
+<FONT size="-1"> The precedence among the syntax rules of translation is specified
+by the following phases.<SUP><A href="
+ #3">3</A></SUP></FONT></P><P>
+<FONT size="-1"> 1. Physical source file characters are mapped to the source character
+ set (introducing new-line characters for end-of-line indicators) if
+ necessary. Trigraph sequences are replaced by corresponding
+ single-character internal representations.
+</FONT></P><P>
+<FONT size="-1"> 2. Each instance of a new-line character and an immediately preceding
+ backslash character is deleted, splicing physical source lines to form
+ logical source lines. A source file that is not empty shall end in a
+ new-line character, which shall not be immediately preceded by a
+ backslash character.
+</FONT></P><P>
+<FONT size="-1"> 3. The source file is decomposed into preprocessing tokens<SUP><A href="
+ #4">4</A></SUP> and
+ sequences of white-space characters (including comments). A source
+ file shall not end in a partial preprocessing token or comment. Each
+ comment is replaced by one space character. New-line characters are
+ retained. Whether each nonempty sequence of other white-space
+ characters is retained or replaced by one space character is
+ implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> 4. Preprocessing directives are executed and macro invocations are
+ expanded. A #include preprocessing directive causes the named header
+ or source file to be processed from phase 1 through phase 4,
+ recursively.
+</FONT></P><P>
+<FONT size="-1"> 5. Each escape sequence in character constants and string literals is
+ converted to a member of the execution character set.
+</FONT></P><P>
+<FONT size="-1"> 6. Adjacent character string literal tokens are concatenated and
+ adjacent wide string literal tokens are concatenated.
+</FONT></P><P>
+<FONT size="-1"> 7. White-space characters separating tokens are no longer
+ significant. Preprocessing tokens are converted into tokens. The
+ resulting tokens are syntactically and semantically analyzed and
+ translated.
+</FONT></P><P>
+<FONT size="-1"> 8. All external object and function references are resolved. Library
+ components are linked to satisfy external references to functions and
+ objects not defined in the current translation. All such translator
+ output is collected into a program image which contains information
+ needed for execution in its execution environment.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ lexical elements (<A href="
+ #3.1">3.1</A>), preprocessing directives
+(<A href="
+ #3.8">3.8</A>), trigraph sequences (<A href="
+ #2.2.1.1">2.2.1.1</A>).
+</FONT></P><H5><A name="2.1.1.3">2.1.1.3 Diagnostics</A></H5>
+<P>
+<FONT size="-1"> A conforming implementation shall produce at least one diagnostic
+message (identified in an implementation-defined manner) for every
+translation unit that contains a violation of any syntax rule or
+constraint. Diagnostic messages need not be produced in other
+circumstances.
+</FONT></P><H4><A name="2.1.2">2.1.2 Execution environments</A></H4>
+<P>
+<FONT size="-1"> Two execution environments are defined: freestanding and hosted.
+In both cases, program startup occurs when a designated C function
+is called by the execution environment. All objects in static storage
+shall be initialized (set to their initial values) before program
+startup. The manner and timing of such initialization are otherwise
+unspecified. Program termination returns control to the execution
+environment.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ initialization (<A href="
+ #3.5.7">3.5.7</A>).
+</FONT></P><H5><A name="2.1.2.1">2.1.2.1 Freestanding environment</A></H5>
+<P>
+<FONT size="-1"> In a freestanding environment (in which C program execution may
+take place without any benefit of an operating system), the name and
+type of the function called at program startup are
+implementation-defined. There are otherwise no reserved external
+identifiers. Any library facilities available to a freestanding
+program are implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> The effect of program termination in a freestanding environment is
+implementation-defined.
+</FONT></P><H5><A name="2.1.2.2">2.1.2.2 Hosted environment</A></H5>
+<P>
+<FONT size="-1"> A hosted environment need not be provided, but shall conform to the
+following specifications if present.
+</FONT></P><P>
+<FONT size="-1">"Program startup"
+</FONT></P><P>
+<FONT size="-1"> The function called at program startup is named main . The
+implementation declares no prototype for this function. It can be
+defined with no parameters:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int main(void) { /*...*/ }
+</FONT></P></PRE><P>
+<FONT size="-1">or with two parameters (referred to here as argc and argv , though any
+names may be used, as they are local to the function in which they are
+declared):
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int main(int argc, char *argv[]) { /*...*/ }
+</FONT></P></PRE><P>
+<FONT size="-1"> If they are defined, the parameters to the main function shall obey
+the following constraints:
+</FONT></P><P>
+<FONT size="-1"> * The value of argc shall be nonnegative.
+</FONT></P><P>
+<FONT size="-1"> * argv[argc] shall be a null pointer.
+</FONT></P><P>
+<FONT size="-1"> * If the value of argc is greater than zero, the array members
+ argv[0] through argv[argc-1] inclusive shall contain pointers to
+ strings, which are given implementation-defined values by the host
+ environment prior to program startup. The intent is to supply to the
+ program information determined prior to program startup from elsewhere
+ in the hosted environment. If the host environment is not capable of
+ supplying strings with letters in both upper-case and lower-case, the
+ implementation shall ensure that the strings are received in
+ lower-case.
+</FONT></P><P>
+<FONT size="-1"> * If the value of argc is greater than zero, the string pointed to by
+ argv[0] represents the program name ;argv[0][0] shall be the null
+ character if the program name is not available from the host
+ environment. If the value of argc is greater than one, the strings
+ pointed to by argv[1] through argv[argc-1] represent the program
+ parameters .
+</FONT></P><P>
+<FONT size="-1"> * The parameters argc and argv and the strings pointed to by the argv
+ array shall be modifiable by the program, and retain their last-stored
+ values between program startup and program termination.
+</FONT></P><P>
+<FONT size="-1">"Program execution"
+</FONT></P><P>
+<FONT size="-1"> In a hosted environment, a program may use all the functions,
+macros, type definitions, and objects described in the library section (<A href="
+ #4.">4.</A>).
+</FONT></P><P>
+<FONT size="-1">"Program termination"
+</FONT></P><P>
+<FONT size="-1"> A return from the initial call to the main function is equivalent
+to calling the exit function with the value returned by the main
+function as its argument. If the main function executes a return that
+specifies no value, the termination status returned to the host
+environment is undefined.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ definition of terms (<A href="
+ #4.1.1">4.1.1</A>), the exit function
+(<A href="
+ #4.10.4.3">4.10.4.3</A>).
+</FONT></P><H5><A name="2.1.2.3">2.1.2.3 Program execution</A></H5>
+<P>
+<FONT size="-1"> The semantic descriptions in this Standard describe the behavior of
+an abstract machine in which issues of optimization are irrelevant.
+</FONT></P><P>
+<FONT size="-1"> Accessing a volatile object, modifying an object, modifying a file,
+or calling a function that does any of those operations are all side
+effects, which are changes in the state of the execution environment.
+Evaluation of an expression may produce side effects. At certain
+specified points in the execution sequence called sequence points, all
+side effects of previous evaluations shall be complete and no side
+effects of subsequent evaluations shall have taken place.
+</FONT></P><P>
+<FONT size="-1"> In the abstract machine, all expressions are evaluated as specified
+by the semantics. An actual implementation need not evaluate part of
+an expression if it can deduce that its value is not used and that no
+needed side effects are produced (including any caused by calling a
+function or accessing a volatile object).
+</FONT></P><P>
+<FONT size="-1"> When the processing of the abstract machine is interrupted by
+receipt of a signal, only the values of objects as of the previous
+sequence point may be relied on. Objects that may be modified between
+the previous sequence point and the next sequence point need not have
+received their correct values yet.
+</FONT></P><P>
+<FONT size="-1"> An instance of each object with automatic storage duration is
+associated with each entry into a block. Such an object exists and
+retains its last-stored value during the execution of the block and
+while the block is suspended (by a call of a function or receipt of a
+signal).
+</FONT></P><P>
+<FONT size="-1"> The least requirements on a conforming implementation are:
+</FONT></P><P>
+<FONT size="-1"> * At sequence points, volatile objects are stable in the sense that
+ previous evaluations are complete and subsequent evaluations have not
+ yet occurred.
+</FONT></P><P>
+<FONT size="-1"> * At program termination, all data written into files shall be
+ identical to the result that execution of the program according to the
+ abstract semantics would have produced.
+</FONT></P><P>
+<FONT size="-1"> * The input and output dynamics of interactive devices shall take
+ place as specified in <A href="
+ #4.9.3">4.9.3</A> The intent of these requirements is
+ that unbuffered or line-buffered output appear as soon as possible, to
+ ensure that prompting messages actually appear prior to a program
+ waiting for input.
+</FONT></P><P>
+<FONT size="-1"> What constitutes an interactive device is implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> More stringent correspondences between abstract and actual
+ semantics may be defined by each implementation.
+</FONT></P><P>
+<FONT size="-1">"Examples"
+</FONT></P><P>
+<FONT size="-1"> An implementation might define a one-to-one correspondence between
+abstract and actual semantics: at every sequence point, the values of
+the actual objects would agree with those specified by the abstract
+semantics. The keyword volatile would then be redundant.
+</FONT></P><P>
+<FONT size="-1"> Alternatively, an implementation might perform various
+optimizations within each translation unit, such that the actual
+semantics would agree with the abstract semantics only when making
+function calls across translation unit boundaries. In such an
+implementation, at the time of each function entry and function return
+where the calling function and the called function are in different
+translation units, the values of all externally linked objects and of
+all objects accessible via pointers therein would agree with the
+abstract semantics. Furthermore, at the time of each such function
+entry the values of the parameters of the called function and of all
+objects accessible via pointers therein would agree with the abstract
+semantics. In this type of implementation, objects referred to by
+interrupt service routines activated by the signal function would
+require explicit specification of volatile storage, as well as other
+implementation-defined restrictions.
+</FONT></P><P>
+<FONT size="-1"> In executing the fragment
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> char c1, c2;
+ /*...*/
+ c1 = c1 + c2;
+</FONT></P></PRE><P>
+<FONT size="-1">the ``integral promotions'' require that the abstract machine promote
+the value of each variable to int size and then add the two int s and
+truncate the sum. Provided the addition of two char s can be done
+without creating an overflow exception, the actual execution need only
+produce the same result, possibly omitting the promotions.
+</FONT></P><P>
+<FONT size="-1"> Similarly, in the fragment
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> float f1, f2;
+ double d;
+ /*...*/
+ f1 = f2 * d;
+</FONT></P></PRE><P>
+<FONT size="-1">the multiplication may be executed using single-precision arithmetic
+if the implementation can ascertain that the result would be the same
+as if it were executed using double-precision arithmetic (for example,
+if d were replaced by the constant 2.0, which has type double ).
+Alternatively, an operation involving only int s or float s may be
+executed using double-precision operations if neither range nor
+precision is lost thereby.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ compound statement, or block (<A href="
+ #3.6.2">3.6.2</A>), files
+(<A href="
+ #4.9.3">4.9.3</A>), sequence points (<A href="
+ #3.3">3.3</A>, <A href="
+ #3.6">3.6</A>), the signal function (<A href="
+ #4.7">4.7</A>),
+type qualifiers (<A href="
+ #3.5.3">3.5.3</A>).
+</FONT></P>
+
+<H3><A name="2.2">2.2 ENVIRONMENTAL CONSIDERATIONS</A></H3>
+<H4><A name="2.2.1">2.2.1 Character sets</A></H4>
+<P>
+<FONT size="-1"> Two sets of characters and their associated collating sequences
+shall be defined: the set in which source files are written, and the
+set interpreted in the execution environment. The values of the
+members of the execution character set are implementation-defined; any
+additional members beyond those required by this section are
+locale-specific.
+</FONT></P><P>
+<FONT size="-1"> In a character constant or string literal, members of the execution
+character set shall be represented by corresponding members of the
+source character set or by escape sequences consisting of the
+backslash \ followed by one or more characters. A byte with all bits
+set to 0, called the null character, shall exist in the basic
+execution character set; it is used to terminate a character string
+literal.
+</FONT></P><P>
+<FONT size="-1"> Both the basic source and basic execution character sets shall have
+at least the following members: the 26 upper-case letters of the
+English alphabet
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> A B C D E F G H I J K L M
+ N O P Q R S T U V W X Y Z
+</FONT></P></PRE><P>
+<FONT size="-1">the 26 lower-case letters of the English alphabet
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> a b c d e f g h i j k l m
+ n o p q r s t u v w x y z
+</FONT></P></PRE><P>
+<FONT size="-1">the 10 decimal digits
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> 0 1 2 3 4 5 6 7 8 9
+</FONT></P></PRE><P>
+<FONT size="-1">the following 29 graphic characters
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> ! " # % & ' ( ) * + , - . / :
+ ; < = > ? [ \ ] ^ _ { | } ~
+</FONT></P></PRE><P>
+<FONT size="-1">the space character, and control characters representing horizontal
+tab, vertical tab, and form feed. In both the source and execution
+basic character sets, the value of each character after 0 in the above
+list of decimal digits shall be one greater than the value of the
+previous. In source files, there shall be some way of indicating the
+end of each line of text; this Standard treats such an end-of-line
+indicator as if it were a single new-line character. In the execution
+character set, there shall be control characters representing alert,
+backspace, carriage return, and new line. If any other characters are
+encountered in a source file (except in a preprocessing token that is
+never converted to a token, a character constant, a string literal, or
+a comment), the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ character constants (<A href="
+ #3.1.3.4">3.1.3.4</A>), preprocessing
+directives (<A href="
+ #3.8">3.8</A>), string literals (<A href="
+ #3.1.4">3.1.4</A>), comments (<A href="
+ #3.1.9">3.1.9</A>).
+</FONT></P><H5><A name="2.2.1.1">2.2.1.1 Trigraph sequences</A></H5>
+<P>
+<FONT size="-1"> All occurrences in a source file of the following sequences of
+three characters (called trigraph sequences<SUP><A href="
+ #5">5</A></SUP>) are replaced with the
+corresponding single character.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> ??= #
+ ??( [
+ ??/ \
+ ??) ]
+ ??' ^
+ ??< {
+ ??! |
+ ??> }
+ ??- ~
+</FONT></P></PRE><P>
+<FONT size="-1">No other trigraph sequences exist. Each ? that does not begin one of
+the trigraphs listed above is not changed.
+</FONT></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> The following source line
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> printf("Eh???/n");
+</FONT></P></PRE><P>
+<FONT size="-1">becomes (after replacement of the trigraph sequence ??/ )
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> printf("Eh?\n");
+</FONT></P></PRE></P><H5><A name="2.2.1.2">2.2.1.2 Multibyte characters</A></H5>
+<P>
+<FONT size="-1"> The source character set may contain multibyte characters, used to
+represent members of the extended character set. The execution
+character set may also contain multibyte characters, which need not
+have the same encoding as for the source character set. For both
+character sets, the following shall hold:
+</FONT></P><P>
+<FONT size="-1"> * The single-byte characters defined in <A href="
+ #2.2.1">2.2.1</A> shall be present.
+</FONT></P><P>
+<FONT size="-1"> * The presence, meaning, and representation of any additional members
+ is locale-specific.
+</FONT></P><P>
+<FONT size="-1"> * A multibyte character may have a state-dependent encoding, wherein
+ each sequence of multibyte characters begins in an initial shift state
+ and enters other implementation-defined shift states when specific
+ multibyte characters are encountered in the sequence. While in the
+ initial shift state, all single-byte characters retain their usual
+ interpretation and do not alter the shift state. The interpretation
+ for subsequent bytes in the sequence is a function of the current
+ shift state.
+</FONT></P><P>
+<FONT size="-1"> * A byte with all bits zero shall be interpreted as a null character
+ independent of shift state.
+</FONT></P><P>
+<FONT size="-1"> * A byte with all bits zero shall not occur in the second or
+ subsequent bytes of a multibyte character.
+</FONT></P><P>
+<FONT size="-1"> For the source character set, the following shall hold:
+</FONT></P><P>
+<FONT size="-1"> * A comment, string literal, character constant, or header name shall
+ begin and end in the initial shift state.
+</FONT></P><P>
+<FONT size="-1"> * A comment, string literal, character constant, or header name shall
+ consist of a sequence of valid multibyte characters.
+</FONT></P><H4><A name="2.2.2">2.2.2 Character display semantics</A></H4>
+<P>
+<FONT size="-1"> The active position is that location on a display device where the
+next character output by the fputc function would appear. The intent
+of writing a printable character (as defined by the isprint function)
+to a display device is to display a graphic representation of that
+character at the active position and then advance the active position
+to the next position on the current line. The direction of printing
+is locale-specific. If the active position is at the final position
+of a line (if there is one), the behavior is unspecified.
+</FONT></P><P>
+<FONT size="-1"> Alphabetic escape sequences representing nongraphic characters in
+the execution character set are intended to produce actions on display
+devices as follows: ( alert ) Produces an audible or visible alert.
+The active position shall not be changed. ( backspace ) Moves the
+active position to the previous position on the current line. If the
+active position is at the initial position of a line, the behavior is
+unspecified. ( "form feed" ) Moves the active position to the initial
+position at the start of the next logical page. ( "new line" ) Moves
+the active position to the initial position of the next line.
+( "carriage return" ) Moves the active position to the initial position
+of the current line. ( "horizontal tab" ) Moves the active position
+to the next horizontal tabulation position on the current line. If
+the active position is at or past the last defined horizontal
+tabulation position, the behavior is unspecified. ( "vertical tab" )
+Moves the active position to the initial position of the next vertical
+tabulation position. If the active position is at or past the last
+defined vertical tabulation position, the behavior is unspecified.
+</FONT></P><P>
+<FONT size="-1"> Each of these escape sequences shall produce a unique
+implementation-defined value which can be stored in a single char
+object. The external representations in a text file need not be
+identical to the internal representations, and are outside the scope
+of this Standard.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the fputc function (<A href="
+ #4.9.7.3">4.9.7.3</A>), the isprint
+function (<A href="
+ #4.3.1.7">4.3.1.7</A>).
+</FONT></P><H4><A name="2.2.3">2.2.3 Signals and interrupts</A></H4>
+<P>
+<FONT size="-1"> Functions shall be implemented such that they may be interrupted at
+any time by a signal, or may be called by a signal handler, or both,
+with no alteration to earlier, but still active, invocations' control
+flow (after the interruption), function return values, or objects with
+automatic storage duration. All such objects shall be maintained
+outside the function image (the instructions that comprise the
+executable representation of a function) on a per-invocation basis.
+</FONT></P><P>
+<FONT size="-1"> The functions in the standard library are not guaranteed to be
+reentrant and may modify objects with static storage duration.
+</FONT></P><H4><A name="2.2.4">2.2.4 Environmental limits</A></H4>
+<P>
+<FONT size="-1"> Both the translation and execution environments constrain the
+implementation of language translators and libraries. The following
+summarizes the environmental limits on a conforming implementation.
+</FONT></P><H5><A name="2.2.4.1">2.2.4.1 Translation limits</A></H5>
+<P>
+<FONT size="-1"> The implementation shall be able to translate and execute at least
+one program that contains at least one instance of every one of the
+following limits:<SUP><A href="
+ #6">6</A></SUP></FONT></P><P>
+<FONT size="-1"> * 15 nesting levels of compound statements, iteration control
+ structures, and selection control structures
+</FONT></P><P>
+<FONT size="-1"> * 8 nesting levels of conditional inclusion
+</FONT></P><P>
+<FONT size="-1"> * 12 pointer, array, and function declarators (in any combinations)
+ modifying an arithmetic, a structure, a union, or an incomplete type
+ in a declaration
+</FONT></P><P>
+<FONT size="-1"> * 31 declarators nested by parentheses within a full declarator
+</FONT></P><P>
+<FONT size="-1"> * 32 expressions nested by parentheses within a full expression
+</FONT></P><P>
+<FONT size="-1"> * 31 significant initial characters in an internal identifier or a
+ macro name
+</FONT></P><P>
+<FONT size="-1"> * 6 significant initial characters in an external identifier
+</FONT></P><P>
+<FONT size="-1"> * 511 external identifiers in one translation unit
+</FONT></P><P>
+<FONT size="-1"> * 127 identifiers with block scope declared in one block
+</FONT></P><P>
+<FONT size="-1"> * 1024 macro identifiers simultaneously defined in one translation unit
+</FONT></P><P>
+<FONT size="-1"> * 31 parameters in one function definition
+</FONT></P><P>
+<FONT size="-1"> * 31 arguments in one function call
+</FONT></P><P>
+<FONT size="-1"> * 31 parameters in one macro definition
+</FONT></P><P>
+<FONT size="-1"> * 31 arguments in one macro invocation
+</FONT></P><P>
+<FONT size="-1"> * 509 characters in a logical source line
+</FONT></P><P>
+<FONT size="-1"> * 509 characters in a character string literal or wide string literal
+ (after concatenation)
+</FONT></P><P>
+<FONT size="-1"> * 32767 bytes in an object (in a hosted environment only)
+</FONT></P><P>
+<FONT size="-1"> * 8 nesting levels for #include'd files
+</FONT></P><P>
+<FONT size="-1"> * 257 case labels for a switch statement (excluding those for any
+ nested switch statements)
+</FONT></P><P>
+<FONT size="-1"> * 127 members in a single structure or union
+</FONT></P><P>
+<FONT size="-1"> * 127 enumeration constants in a single enumeration
+</FONT></P><P>
+<FONT size="-1"> * 15 levels of nested structure or union definitions in a single
+ struct-declaration-list
+</FONT></P><H5><A name="2.2.4.2">2.2.4.2 Numerical limits</A></H5>
+<P>
+<FONT size="-1"> A conforming implementation shall document all the limits specified
+in this section, which shall be specified in the headers <limits.h>
+and <float.h> .
+</FONT></P><P>
+<FONT size="-1">"Sizes of integral types <limits.h>"
+</FONT></P><P>
+<FONT size="-1"> The values given below shall be replaced by constant expressions
+suitable for use in #if preprocessing directives. Their
+implementation-defined values shall be equal or greater in magnitude
+(absolute value) to those shown, with the same sign.
+</FONT></P><P>
+<FONT size="-1"> * maximum number of bits for smallest object that is not a bit-field (byte)
+CHAR_BIT 8
+</FONT></P><P>
+<FONT size="-1"> * minimum value for an object of type signed char
+SCHAR_MIN -127
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type signed char
+SCHAR_MAX +127
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type unsigned char
+UCHAR_MAX 255
+</FONT></P><P>
+<FONT size="-1"> * minimum value for an object of type char
+CHAR_MIN see below
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type char
+CHAR_MAX see below
+</FONT></P><P>
+<FONT size="-1"> * maximum number of bytes in a multibyte character, for any supported locale
+MB_LEN_MAX 1
+</FONT></P><P>
+<FONT size="-1"> * minimum value for an object of type short int
+SHRT_MIN -32767
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type short int
+SHRT_MAX +32767
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type unsigned short int
+USHRT_MAX 65535
+</FONT></P><P>
+<FONT size="-1"> * minimum value for an object of type int
+INT_MIN -32767
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type int
+INT_MAX +32767
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type unsigned int
+UINT_MAX 65535
+</FONT></P><P>
+<FONT size="-1"> * minimum value for an object of type long int
+LONG_MIN -2147483647
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type long int
+LONG_MAX +2147483647
+</FONT></P><P>
+<FONT size="-1"> * maximum value for an object of type unsigned long int
+ULONG_MAX 4294967295
+</FONT></P><P>
+<FONT size="-1"> If the value of an object of type char sign-extends when used in an
+expression, the value of CHAR_MIN shall be the same as that of
+SCHAR_MIN and the value of CHAR_MAX shall be the same as that of
+SCHAR_MAX . If the value of an object of type char does not
+sign-extend when used in an expression, the value of CHAR_MIN shall be
+0 and the value of CHAR_MAX shall be the same as that of UCHAR_MAX
+.<SUP><A href="
+ #7">7</A></SUP></FONT></P><P>
+<FONT size="-1">"Characteristics of floating types <float.h>"
+</FONT></P><P>
+<FONT size="-1"> delim $$ The characteristics of floating types are defined in terms
+of a model that describes a representation of floating-point numbers
+and values that provide information about an implementation's
+floating-point arithmetic. The following parameters are used to
+define the model for each floating-point type:
+</FONT></P><P>
+<FONT size="-1"> A normalized floating-point number x ($f sub 1$ > 0 if x is defined
+by the following model:<SUP><A href="
+ #8">8</A></SUP> $x~=~s~times~b sup e~times~sum from k=1 to
+p~f sub k~times~b sup -k~,~~~e sub min~<=~e~<=~e sub max$
+</FONT></P><P>
+<FONT size="-1"> Of the values in the <float.h> header, FLT_RADIX shall be a
+constant expression suitable for use in #if preprocessing directives;
+all other values need not be constant expressions. All except
+FLT_RADIX and FLT_ROUNDS have separate names for all three
+floating-point types. The floating-point model representation is
+provided for all values except FLT_ROUNDS .
+</FONT></P><P>
+<FONT size="-1"> The rounding mode for floating-point addition is characterized by
+the value of FLT_ROUNDS : -1 indeterminable, 0 toward zero, 1 to nearest,
+2 toward positive infinity, 3 toward negative infinity. All other values
+for FLT_ROUNDS characterize implementation-defined rounding behavior.
+</FONT></P><P>
+<FONT size="-1"> The values given in the following list shall be replaced by
+implementation-defined expressions that shall be equal or greater in
+magnitude (absolute value) to those shown, with the same sign.
+</FONT></P><P>
+<FONT size="-1"> * radix of exponent representation, b
+FLT_RADIX 2
+</FONT></P><P>
+<FONT size="-1"> * number of base- FLT_RADIX digits in the floating-point mantissa, p
+</FONT></P><P>
+<FONT size="-1">FLT_MANT_DIG
+DBL_MANT_DIG
+LDBL_MANT_DIG
+</FONT></P><P>
+<FONT size="-1"> * number of decimal digits of precision, $left floor~(p~-~1)~times~{
+ log sub 10 } b~right floor ~+~ left { lpile { 1 above 0 } ~~ lpile {
+ roman "if " b roman " is a power of 10" above roman otherwise }$
+</FONT></P><P>
+<FONT size="-1">FLT_DIG 6
+DBL_DIG 10
+LDBL_DIG 10
+</FONT></P><P>
+<FONT size="-1"> * minimum negative integer such that FLT_RADIX raised to that power
+ minus 1 is a normalized floating-point number, $e sub min$
+</FONT></P><P>
+<FONT size="-1">FLT_MIN_EXP
+DBL_MIN_EXP
+LDBL_MIN_EXP
+</FONT></P><P>
+<FONT size="-1"> * minimum negative integer such that 10 raised to that power is in
+ the range of normalized floating-point numbers,
+</FONT></P><P>
+<FONT size="-1">FLT_MIN_10_EXP -37
+DBL_MIN_10_EXP -37
+LDBL_MIN_10_EXP -37
+</FONT></P><P>
+<FONT size="-1"> * maximum integer such that FLT_RADIX raised to that power minus 1 is
+ a representable finite floating-point number, $e sub max$
+</FONT></P><P>
+<FONT size="-1">FLT_MAX_EXP
+DBL_MAX_EXP
+LDBL_MAX_EXP
+</FONT></P><P>
+<FONT size="-1"> * maximum integer such that 10 raised to that power is in the range
+ of representable finite floating-point numbers,
+</FONT></P><P>
+<FONT size="-1">FLT_MAX_10_EXP +37
+DBL_MAX_10_EXP +37
+LDBL_MAX_10_EXP +37
+</FONT></P><P>
+<FONT size="-1"> The values given in the following list shall be replaced by
+implementation-defined expressions with values that shall be equal to
+or greater than those shown.
+</FONT></P><P>
+<FONT size="-1"> * maximum representable finite floating-point number,
+</FONT></P><P>
+<FONT size="-1">FLT_MAX 1E+37
+DBL_MAX 1E+37
+LDBL_MAX 1E+37
+</FONT></P><P>
+<FONT size="-1"> The values given in the following list shall be replaced by
+implementation-defined expressions with values that shall be equal to
+or smaller than those shown.
+</FONT></P><P>
+<FONT size="-1"> * minimum positive floating-point number x such that 1.0 + x
+</FONT></P><P>
+<FONT size="-1">FLT_EPSILON 1E-5
+DBL_EPSILON 1E-9
+LDBL_EPSILON 1E-9
+</FONT></P><P>
+<FONT size="-1"> * minimum normalized positive floating-point number, $b sup { e sub
+ min - 1 }$
+</FONT></P><P>
+<FONT size="-1">FLT_MIN 1E-37
+DBL_MIN 1E-37
+LDBL_MIN 1E-37
+</FONT></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The following describes an artificial floating-point representation
+that meets the minimum requirements of the Standard, and the
+appropriate values in a <float.h> header for type float :
+$x~=~s~times~16 sup e~times~sum from k=1 to 6~f sub k~times~16 sup
+-k~,~~~-31~<=~e~<=~+32$
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> FLT_RADIX 16
+ FLT_MANT_DIG 6
+ FLT_EPSILON 9.53674316E-07F
+ FLT_DIG 6
+ FLT_MIN_EXP -31
+ FLT_MIN 2.93873588E-39F
+ FLT_MIN_10_EXP -38
+ FLT_MAX_EXP +32
+ FLT_MAX 3.40282347E+38F
+ FLT_MAX_10_EXP +38
+</FONT></P></PRE><P>
+<FONT size="-1"> The following describes floating-point representations that also
+meet the requirements for single-precision and double-precision
+normalized numbers in the IEEE Standard for Binary Floating-Point
+Arithmetic (ANSI/IEEE Std 754-1985),<SUP><A href="
+ #9">9</A></SUP> b and the appropriate values
+in a <float.h> header for types float and double : $x sub
+f~=~s~times~2 sup e~times~{ sum from k=1 to 24~f sub k~times~2 sup -k
+},~~~-125~<=~e~<=~+128$ $x sub d~=~s~times~2 sup e~times~{ sum from
+k=1 to 53~f sub k~times~2 sup -k },~~~-1021~<=~e~<=~+1024$
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> FLT_RADIX 2
+ FLT_MANT_DIG 24
+ FLT_EPSILON 1.19209290E-07F
+ FLT_DIG 6
+ FLT_MIN_EXP -125
+ FLT_MIN 1.17549435E-38F
+ FLT_MIN_10_EXP -37
+ FLT_MAX_EXP +128
+ FLT_MAX 3.40282347E+38F
+ FLT_MAX_10_EXP +38
+ DBL_MANT_DIG 53
+ DBL_EPSILON 2.2204460492503131E-16
+ DBL_DIG 15
+ DBL_MIN_EXP -1021
+ DBL_MIN 2.2250738585072016E-308
+ DBL_MIN_10_EXP -307
+ DBL_MAX_EXP +1024
+ DBL_MAX 1.7976931348623157E+308
+ DBL_MAX_10_EXP +308
+</FONT></P></PRE><P>
+<FONT size="-1"> The values shown above for FLT_EPSILON and DBL_EPSILON are
+appropriate for the ANSI/IEEE Std 754-1985 default rounding mode (to
+nearest). Their values may differ for other rounding modes.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ conditional inclusion (<A href="
+ #3.8.1">3.8.1</A>). conditional
+inclusion (<A href="
+ #3.8.1">3.8.1</A>).
+</FONT></P>
+
+<H2><A name="3.">3. LANGUAGE</A></H2>
+<P>
+<FONT size="-1"> In the syntax notation used in the language section (<A href="
+ #3.">3.</A>), syntactic
+categories (nonterminals) are indicated by italic type, and literal
+words and character set members (terminals) by bold type. A colon (:)
+following a nonterminal introduces its definition. Alternative
+definitions are listed on separate lines, except when prefaced by the
+words ``one of.'' An optional symbol is indicated by the so that
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> { expression<opt> }
+</FONT></P></PRE><P>
+<FONT size="-1">indicates an optional expression enclosed in braces.
+</FONT></P><H3><A name="3.1">3.1 LEXICAL ELEMENTS</A></H3>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="token">token</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #keyword">keyword</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #constant">constant</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #string-literal">string-literal</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #operator">operator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #punctuator">punctuator</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="preprocessing-token">preprocessing-token</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #header-name">header-name</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-number">pp-number</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #character-constant">character-constant</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #string-literal">string-literal</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #operator">operator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #punctuator">punctuator</A></FONT></P>
+ <P class="regulartext-nonterm">
+<FONT size="-1">each non-white-space character that cannot be one of the above</FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each preprocessing token that is converted to a token shall have
+the lexical form of a keyword, an identifier, a constant, a string
+literal, an operator, or a punctuator.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A token is the minimal lexical element of the language in
+translation phases 7 and 8. The categories of tokens are: keywords,
+identifiers, constants, string literals, operators, and punctuators.
+A preprocessing token is the minimal lexical element of the language
+in translation phases 3 through 6. The categories of preprocessing
+token are: header names, identifiers, preprocessing numbers,
+character constants, string literals, operators, punctuators, and
+single non-white-space characters that do not lexically match the
+other preprocessing token categories. If a ' or a " character matches
+the last category, the behavior is undefined. Comments (described
+later) and the characters space, horizontal tab, new-line, vertical
+tab, and form-feed --- collectively called white space --- can separate
+preprocessing tokens. As described in <A href="
+ #3.8">3.8</A>, in certain circumstances
+during translation phase 4, white space (or the absence thereof)
+serves as more than preprocessing token separation. White space may
+appear within a preprocessing token only as part of a header name or
+between the quotation characters in a character constant or string
+literal.
+</FONT></P><P>
+<FONT size="-1"> If the input stream has been parsed into preprocessing tokens up to
+a given character, the next preprocessing token is the longest
+sequence of characters that could constitute a preprocessing token.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The program fragment 1Ex is parsed as a preprocessing number token
+(one that is not a valid floating or integer constant token), even
+though a parse as the pair of preprocessing tokens 1 and Ex might
+produce a valid expression (for example, if Ex were a macro defined as
++1 ). Similarly, the program fragment 1E1 is parsed as a
+preprocessing number (one that is a valid floating constant token),
+whether or not E is a macro name.
+</FONT></P><P>
+<FONT size="-1"> The program fragment x+++++y is parsed as x ++ ++ + y, which
+violates a constraint on increment operators, even though the parse x
+++ + ++ y might yield a correct expression.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ character constants (<A href="
+ #3.1.3.4">3.1.3.4</A>), comments (<A href="
+ #3.1.9">3.1.9</A>),
+expressions (<A href="
+ #3.3">3.3</A>), floating constants (<A href="
+ #3.1.3.1">3.1.3.1</A>), header names
+(<A href="
+ #3.1.7">3.1.7</A>), macro replacement (<A href="
+ #3.8.3">3.8.3</A>), postfix increment and decrement
+operators (<A href="
+ #3.3.2.4">3.3.2.4</A>), prefix increment and decrement operators
+(<A href="
+ #3.3.3.1">3.3.3.1</A>), preprocessing directives (<A href="
+ #3.8">3.8</A>), preprocessing numbers
+(<A href="
+ #3.1.8">3.1.8</A>), string literals (<A href="
+ #3.1.4">3.1.4</A>).
+</FONT></P><H4><A name="3.1.1">3.1.1 Keywords</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="keyword">keyword</A></FONT><FONT size="-1">: one of</FONT><BR></P><P class="syntax-def"> <P class="nonterm-defseq">
+<FONT class="term">auto</FONT> <FONT class="term">double</FONT> <FONT class="term">int</FONT> <FONT class="term">struct</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">break</FONT> <FONT class="term">else</FONT> <FONT class="term">long</FONT> <FONT class="term">switch</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">case</FONT> <FONT class="term">enum</FONT> <FONT class="term">register</FONT> <FONT class="term">typedef</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">char</FONT> <FONT class="term">extern</FONT> <FONT class="term">return</FONT> <FONT class="term">union</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">const</FONT> <FONT class="term">float</FONT> <FONT class="term">short</FONT> <FONT class="term">unsigned</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">continue</FONT> <FONT class="term">for</FONT> <FONT class="term">signed</FONT> <FONT class="term">void</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">default</FONT> <FONT class="term">goto</FONT> <FONT class="term">sizeof</FONT> <FONT class="term">volatile</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">do</FONT> <FONT class="term">if</FONT> <FONT class="term">static</FONT> <FONT class="term">while</FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The above tokens (entirely in lower-case) are reserved (in
+translation phases 7 and 8) for use as keywords, and shall not be used
+otherwise.
+</FONT></P></P><H4><A name="3.1.2">3.1.2 Identifiers</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="identifier">identifier</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #nondigit">nondigit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> <FONT class="nonterm"><A href="
+ #nondigit">nondigit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> <FONT class="nonterm"><A href="
+ #digit">digit</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="nondigit">nondigit</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">_</FONT> <FONT class="term">a</FONT> <FONT class="term">b</FONT> <FONT class="term">c</FONT> <FONT class="term">d</FONT> <FONT class="term">e</FONT> <FONT class="term">f</FONT> <FONT class="term">g</FONT> <FONT class="term">h</FONT> <FONT class="term">i</FONT> <FONT class="term">j</FONT> <FONT class="term">k</FONT> <FONT class="term">l</FONT> <FONT class="term">m</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">n</FONT> <FONT class="term">o</FONT> <FONT class="term">p</FONT> <FONT class="term">q</FONT> <FONT class="term">r</FONT> <FONT class="term">s</FONT> <FONT class="term">t</FONT> <FONT class="term">u</FONT> <FONT class="term">v</FONT> <FONT class="term">w</FONT> <FONT class="term">x</FONT> <FONT class="term">y</FONT> <FONT class="term">z</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">A</FONT> <FONT class="term">B</FONT> <FONT class="term">C</FONT> <FONT class="term">D</FONT> <FONT class="term">E</FONT> <FONT class="term">F</FONT> <FONT class="term">G</FONT> <FONT class="term">H</FONT> <FONT class="term">I</FONT> <FONT class="term">J</FONT> <FONT class="term">K</FONT> <FONT class="term">L</FONT> <FONT class="term">M</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">N</FONT> <FONT class="term">O</FONT> <FONT class="term">P</FONT> <FONT class="term">Q</FONT> <FONT class="term">R</FONT> <FONT class="term">S</FONT> <FONT class="term">T</FONT> <FONT class="term">U</FONT> <FONT class="term">V</FONT> <FONT class="term">W</FONT> <FONT class="term">X</FONT> <FONT class="term">Y</FONT> <FONT class="term">Z</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="digit">digit</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">0</FONT> <FONT class="term">1</FONT> <FONT class="term">2</FONT> <FONT class="term">3</FONT> <FONT class="term">4</FONT> <FONT class="term">5</FONT> <FONT class="term">6</FONT> <FONT class="term">7</FONT> <FONT class="term">8</FONT> <FONT class="term">9</FONT></P></P></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> An identifier is a sequence of nondigit characters (including the
+underscore _ and the lower-case and upper-case letters) and digits.
+The first character shall be a nondigit character.
+</FONT></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> In translation phases 7 and 8, an identifier shall not consist of
+the same sequence of characters as a keyword.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An identifier denotes an object, a function, or one of the
+following entities that will be described later: a tag or a member of
+a structure, union, or enumeration; a typedef name; a label name; a
+macro name; or a macro parameter. A member of an enumeration is
+called an enumeration constant. Macro names and macro parameters are
+not considered further here, because prior to the semantic phase of
+program translation any occurrences of macro names in the source file
+are replaced by the preprocessing token sequences that constitute
+their macro definitions.
+</FONT></P><P>
+<FONT size="-1"> There is no specific limit on the maximum length of an identifier.
+</FONT></P><P>
+<FONT size="-1">"Implementation limits"
+</FONT></P><P>
+<FONT size="-1"> The implementation shall treat at least the first 31 characters of
+an internal name (a macro name or an identifier that does not have
+external linkage) as significant. Corresponding lower-case and
+upper-case letters are different. The implementation may further
+restrict the significance of an external name (an identifier that has
+external linkage) to six characters and may ignore distinctions of
+alphabetical case for such names.<SUP><A href="
+ #10">10</A></SUP> These limitations on identifiers
+are all implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> Any identifiers that differ in a significant character are
+different identifiers. If two identifiers differ in a non-significant
+character, the behavior is undefined.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ linkages of identifiers (<A href="
+ #3.1.2.2">3.1.2.2</A>), macro
+replacement (<A href="
+ #3.8.3">3.8.3</A>).
+</FONT></P><H5><A name="3.1.2.1">3.1.2.1 Scopes of identifiers</A></H5>
+<P>
+<FONT size="-1"> An identifier is visible (i.e., can be used) only within a region
+of program text called its scope . There are four kinds of scopes:
+function, file, block, and function prototype. (A function prototype
+is a declaration of a function that declares the types of its
+parameters.)
+</FONT></P><P>
+<FONT size="-1"> A label name is the only kind of identifier that has function scope.
+It can be used (in a goto statement) anywhere in the function in
+which it appears, and is declared implicitly by its syntactic
+appearance (followed by a : and a statement). Label names shall be
+unique within a function.
+</FONT></P><P>
+<FONT size="-1"> Every other identifier has scope determined by the placement of its
+declaration (in a declarator or type specifier). If the declarator or
+type specifier that declares the identifier appears outside of any
+block or list of parameters, the identifier has file scope, which
+terminates at the end of the translation unit. If the declarator or
+type specifier that declares the identifier appears inside a block or
+within the list of parameter declarations in a function definition,
+the identifier has block scope, which terminates at the } that closes
+the associated block. If the declarator or type specifier that
+declares the identifier appears within the list of parameter
+declarations in a function prototype (not part of a function
+definition), the identifier has function prototype scope, which
+terminates at the end of the function declarator. If an outer
+declaration of a lexically identical identifier exists in the same
+name space, it is hidden until the current scope terminates, after
+which it again becomes visible.
+</FONT></P><P>
+<FONT size="-1"> Structure, union, and enumeration tags have scope that begins just
+after the appearance of the tag in a type specifier that declares the
+tag. Each enumeration constant has scope that begins just after the
+appearance of its defining enumerator in an enumerator list. Any
+other identifier has scope that begins just after the completion of
+its declarator.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ compound statement, or block (<A href="
+ #3.6.2">3.6.2</A>),
+declarations (<A href="
+ #3.5">3.5</A>), enumeration specifiers (<A href="
+ #3.5.2.2">3.5.2.2</A>), function calls
+(<A href="
+ #3.3.2.2">3.3.2.2</A>), function declarators (including prototypes) (<A href="
+ #3.5.4.3">3.5.4.3</A>),
+function definitions (<A href="
+ #3.7.1">3.7.1</A>), the goto statement (<A href="
+ #3.6.6.1">3.6.6.1</A>), labeled
+statements (<A href="
+ #3.6.1">3.6.1</A>), name spaces of identifiers (<A href="
+ #3.1.2.3">3.1.2.3</A>), scope of
+macro definitions (<A href="
+ #3.8.3.5">3.8.3.5</A>), source file inclusion (<A href="
+ #3.8.2">3.8.2</A>), tags
+(<A href="
+ #3.5.2.3">3.5.2.3</A>), type specifiers (<A href="
+ #3.5.2">3.5.2</A>).
+</FONT></P><H5><A name="3.1.2.2">3.1.2.2 Linkages of identifiers</A></H5>
+<P>
+<FONT size="-1"> An identifier declared in different scopes or in the same scope
+more than once can be made to refer to the same object or function by
+a process called linkage . There are three kinds of linkage: external,
+internal, and none.
+</FONT></P><P>
+<FONT size="-1"> In the set of translation units and libraries that constitutes an
+entire program, each instance of a particular identifier with external
+linkage denotes the same object or function. Within one translation
+unit, each instance of an identifier with internal linkage denotes the
+same object or function. Identifiers with no linkage denote unique
+entities.
+</FONT></P><P>
+<FONT size="-1"> If the declaration of an identifier for an object or a function has
+file scope and contains the storage-class specifier static, the
+identifier has internal linkage.
+</FONT></P><P>
+<FONT size="-1"> If the declaration of an identifier for an object or a function
+contains the storage-class specifier extern , the identifier has the
+same linkage as any visible declaration of the identifier with file
+scope. If there is no visible declaration with file scope, the
+identifier has external linkage.
+</FONT></P><P>
+<FONT size="-1"> If the declaration of an identifier for a function has no
+storage-class specifier, its linkage is determined exactly as if it
+were declared with the storage-class specifier extern . If the
+declaration of an identifier for an object has file scope and no
+storage-class specifier, its linkage is external.
+</FONT></P><P>
+<FONT size="-1"> The following identifiers have no linkage: an identifier declared
+to be anything other than an object or a function; an identifier
+declared to be a function parameter; an identifier declared to be an
+object inside a block without the storage-class specifier extern.
+</FONT></P><P>
+<FONT size="-1"> If, within a translation unit, the same identifier appears with
+both internal and external linkage, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ compound statement, or block (<A href="
+ #3.6.2">3.6.2</A>),
+declarations (<A href="
+ #3.5">3.5</A>), expressions (<A href="
+ #3.3">3.3</A>), external definitions (<A href="
+ #3.7">3.7</A>).
+</FONT></P><H5><A name="3.1.2.3">3.1.2.3 Name spaces of identifiers</A></H5>
+<P>
+<FONT size="-1"> If more than one declaration of a particular identifier is visible
+at any point in a translation unit, the syntactic context
+disambiguates uses that refer to different entities. Thus, there are
+separate name spaces for various categories of identifiers, as
+follows:
+</FONT></P><P>
+<FONT size="-1"> * label names (disambiguated by the syntax of the label declaration
+ and use);
+</FONT></P><P>
+<FONT size="-1"> * the tags of structures, unions, and enumerations (disambiguated by
+ following any<SUP><A href="
+ #11">11</A></SUP> of the keywords struct , union , or enum );
+</FONT></P><P>
+<FONT size="-1"> * the members of structures or unions; each structure or union has a
+ separate name space for its members (disambiguated by the type of the
+ expression used to access the member via the . or -> operator);
+</FONT></P><P>
+<FONT size="-1"> * all other identifiers, called ordinary identifiers (declared in
+ ordinary declarators or as enumeration constants).
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ declarators (<A href="
+ #3.5.4">3.5.4</A>), enumeration specifiers
+(<A href="
+ #3.5.2.2">3.5.2.2</A>), labeled statements (<A href="
+ #3.6.1">3.6.1</A>), structure and union
+specifiers (<A href="
+ #3.5.2.1">3.5.2.1</A>), structure and union members (<A href="
+ #3.3.2.3">3.3.2.3</A>), tags
+(<A href="
+ #3.5.2.3">3.5.2.3</A>).
+</FONT></P><H5><A name="3.1.2.4">3.1.2.4 Storage durations of objects</A></H5>
+<P>
+<FONT size="-1"> An object has a storage duration that determines its lifetime.
+There are two storage durations: static and automatic.
+</FONT></P><P>
+<FONT size="-1"> An object declared with external or internal linkage, or with the
+storage-class specifier static has static storage duration. For such
+an object, storage is reserved and its stored value is initialized
+only once, prior to program startup. The object exists and retains
+its last-stored value throughout the execution of the entire
+program.<SUP><A href="
+ #12">12</A></SUP></FONT></P><P>
+<FONT size="-1"> An object declared with no linkage and without the storage-class
+specifier static has automatic storage duration. Storage is guaranteed
+to be reserved for a new instance of such an object on each normal
+entry into the block in which it is declared, or on a jump from
+outside the block to a label in the block or in an enclosed block. If
+an initialization is specified for the value stored in the object, it
+is performed on each normal entry, but not if the block is entered by
+a jump to a label. Storage for the object is no longer guaranteed to
+be reserved when execution of the block ends in any way. (Entering an
+enclosed block suspends but does not end execution of the enclosing
+block. Calling a function that returns suspends but does not end
+execution of the block containing the call.) The value of a pointer
+that referred to an object with automatic storage duration that is no
+longer guaranteed to be reserved is indeterminate.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ compound statement, or block (<A href="
+ #3.6.2">3.6.2</A>), function
+calls (<A href="
+ #3.3.2.2">3.3.2.2</A>), initialization (<A href="
+ #3.5.7">3.5.7</A>).
+</FONT></P><H5><A name="3.1.2.5">3.1.2.5 Types</A></H5>
+<P>
+<FONT size="-1"> The meaning of a value stored in an object or returned by a
+function is determined by the type of the expression used to access
+it. (An identifier declared to be an object is the simplest such
+expression; the type is specified in the declaration of the
+identifier.) Types are partitioned into object types (types that
+describe objects), function types (types that describe functions), and
+incomplete types (types that describe objects but lack information
+needed to determine their sizes).
+</FONT></P><P>
+<FONT size="-1"> An object declared as type char is large enough to store any member
+of the basic execution character set. If a member of the required
+source character set enumerated in <A href="
+ #2.2.1">2.2.1</A> is stored in a char object,
+its value is guaranteed to be positive. If other quantities are
+stored in a char object, the behavior is implementation-defined: the
+values are treated as either signed or nonnegative integers.
+</FONT></P><P>
+<FONT size="-1"> There are four signed integer types, designated as signed char,
+short int, int, and long int. (The signed integer and other types
+may be designated in several additional ways, as described in <A href="
+ #3.5.2">3.5.2</A>)
+</FONT></P><P>
+<FONT size="-1"> An object declared as type signed char occupies the same amount of
+storage as a ``plain'' char object. A ``plain'' int object has the
+natural size suggested by the architecture of the execution
+environment (large enough to contain any value in the range INT_MIN to
+INT_MAX as defined in the header <limits.h> ). In the list of signed
+integer types above, the range of values of each type is a subrange of
+the values of the next type in the list.
+</FONT></P><P>
+<FONT size="-1"> For each of the signed integer types, there is a corresponding (but
+different) unsigned integer type (designated with the keyword unsigned)
+that uses the same amount of storage (including sign information)
+and has the same alignment requirements. The range of nonnegative
+values of a signed integer type is a subrange of the corresponding
+unsigned integer type, and the representation of the same value in
+each type is the same. A computation involving unsigned operands can
+never overflow, because a result that cannot be represented by the
+resulting unsigned integer type is reduced modulo the number that is
+one greater than the largest value that can be represented by the
+resulting unsigned integer type.
+</FONT></P><P>
+<FONT size="-1"> There are three floating types, designated as float , double , and
+long double . The set of values of the type float is a subset of the
+set of values of the type double ; the set of values of the type
+double is a subset of the set of values of the type long double.
+</FONT></P><P>
+<FONT size="-1"> The type char, the signed and unsigned integer types, and the
+floating types are collectively called the basic types. Even if the
+implementation defines two or more basic types to have the same
+representation, they are nevertheless different types.
+</FONT></P><P>
+<FONT size="-1"> There are three character types, designated as char , signed char ,
+and unsigned char.
+</FONT></P><P>
+<FONT size="-1"> An enumeration comprises a set of named integer constant values.
+Each distinct enumeration constitutes a different enumerated type.
+</FONT></P><P>
+<FONT size="-1"> The void type comprises an empty set of values; it is an incomplete
+type that cannot be completed.
+</FONT></P><P>
+<FONT size="-1"> Any number of derived types can be constructed from the basic,
+enumerated, and incomplete types, as follows:
+</FONT></P><P>
+<FONT size="-1"> * An array type describes a contiguously allocated set of objects
+ with a particular member object type, called the element type .Array
+ types are characterized by their element type and by the number of
+ members of the array. An array type is said to be derived from its
+ element type, and if its element type is T , the array type is
+ sometimes called ``array of T .'' The construction of an array type
+ from an element type is called ``array type derivation.''
+</FONT></P><P>
+<FONT size="-1"> * A structure type describes a sequentially allocated set of member
+ objects, each of which has an optionally specified name and possibly
+ distinct type.
+</FONT></P><P>
+<FONT size="-1"> * A union type describes an overlapping set of member objects, each
+ of which has an optionally specified name and possibly distinct type.
+</FONT></P><P>
+<FONT size="-1"> * A function type describes a function with specified return type. A
+ function type is characterized by its return type and the number and
+ types of its parameters. A function type is said to be derived from
+ its return type, and if its return type is T , the function type is
+ sometimes called ``function returning T.'' The construction of a
+ function type from a return type is called ``function type
+ derivation.''
+</FONT></P><P>
+<FONT size="-1"> * A pointer type may be derived from a function type, an object type,
+ or an incomplete type, called the referenced type. A pointer type
+ describes an object whose value provides a reference to an entity of
+ the referenced type. A pointer type derived from the referenced type
+ T is sometimes called ``pointer to T .'' The construction of a pointer
+ type from a referenced type is called ``pointer type derivation.''
+</FONT></P><P>
+<FONT size="-1"> These methods of constructing derived types can be applied
+recursively.
+</FONT></P><P>
+<FONT size="-1"> The type char, the signed and unsigned integer types, and the
+enumerated types are collectively called integral types. The
+representations of integral types shall define values by use of a pure
+binary numeration system.<SUP><A href="
+ #13">13</A></SUP> American National Dictionary for
+Information Processing Systems.) The representations of floating types
+are unspecified.
+</FONT></P><P>
+<FONT size="-1"> Integral and floating types are collectively called arithmetic
+types. Arithmetic types and pointer types are collectively called
+scalar types. Array and structure types are collectively called
+aggregate types.<SUP><A href="
+ #14">14</A></SUP></FONT></P><P>
+<FONT size="-1"> A pointer to void shall have the same representation and alignment
+requirements as a pointer to a character type. Other pointer types
+need not have the same representation or alignment requirements.
+</FONT></P><P>
+<FONT size="-1"> An array type of unknown size is an incomplete type. It is
+completed, for an identifier of that type, by specifying the size in a
+later declaration (with internal or external linkage). A structure or
+union type of unknown content (as described in <A href="
+ #3.5.2.3">3.5.2.3</A>) is an
+incomplete type. It is completed, for all declarations of that type,
+by declaring the same structure or union tag with its defining content
+later in the same scope.
+</FONT></P><P>
+<FONT size="-1"> Array, function, and pointer types are collectively called derived
+declarator types. A declarator type derivation from a type T is the
+construction of a derived declarator type from T by the application of
+an array, a function, or a pointer type derivation to T.
+</FONT></P><P>
+<FONT size="-1"> A type is characterized by its top type, which is either the first
+type named in describing a derived type (as noted above in the
+construction of derived types), or the type itself if the type
+consists of no derived types.
+</FONT></P><P>
+<FONT size="-1"> A type has qualified type if its top type is specified with a type
+qualifier; otherwise it has unqualified type. The type qualifiers
+const and volatile respectively designate const-qualified type and
+volatile-qualified type.<SUP><A href="
+ #15">15</A></SUP> For each qualified type there is an
+unqualified type that is specified the same way as the qualified type,
+but without any type qualifiers in its top type. This type is known
+as the unqualified version of the qualified type. Similarly, there
+are appropriately qualified versions of types (such as a
+const-qualified version of a type), just as there are appropriately
+non-qualified versions of types (such as a non-const-qualified version
+of a type).
+</FONT></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The type designated as ``float *'' is called ``pointer to float''
+and its top type is a pointer type, not a floating type. The
+const-qualified version of this type is designated as ``float * const''
+whereas the type designated as `` const float * '' is not a
+qualified type --- it is called ``pointer to const float '' and is a
+pointer to a qualified type.
+</FONT></P><P>
+<FONT size="-1"> Finally, the type designated as `` struct tag (*[5])(float) '' is
+called ``array of pointer to function returning struct tag.'' Its top
+type is array type. The array has length five and the function has a
+single parameter of type float.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ character constants (<A href="
+ #3.1.3.4">3.1.3.4</A>), declarations
+(<A href="
+ #3.5">3.5</A>), tags (<A href="
+ #3.5.2.3">3.5.2.3</A>), type qualifiers (<A href="
+ #3.5.3">3.5.3</A>).
+</FONT></P><H5><A name="3.1.2.6">3.1.2.6 Compatible type and composite type</A></H5>
+<P>
+<FONT size="-1"> Two types have compatible type if their types are the same.
+Additional rules for determining whether two types are compatible are
+described in <A href="
+ #3.5.2">3.5.2</A> for type specifiers, in <A href="
+ #3.5.3">3.5.3</A> for type
+qualifiers, and in <A href="
+ #3.5.4">3.5.4</A> for declarators.<SUP><A href="
+ #16">16</A></SUP> Moreover, two
+structure, union, or enumeration types declared in separate
+translation units are compatible if they have the same number of
+members, the same member names, and compatible member types; for two
+structures, the members shall be in the same order; for two
+enumerations, the members shall have the same values.
+</FONT></P><P>
+<FONT size="-1"> All declarations that refer to the same object or function shall
+have compatible type; otherwise the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> A composite type can be constructed from two types that are
+compatible; it is a type that is compatible with both of the two types
+and has the following additions:
+</FONT></P><P>
+<FONT size="-1"> * If one type is an array of known size, the composite type is an
+ array of that size.
+</FONT></P><P>
+<FONT size="-1"> * If only one type is a function type with a parameter type list (a
+ function prototype), the composite type is a function prototype with
+ the parameter type list.
+</FONT></P><P>
+<FONT size="-1"> * If both types have parameter type lists, the type of each parameter
+ in the composite parameter type list is the composite type of the
+ corresponding parameters.
+</FONT></P><P>
+<FONT size="-1"> These rules apply recursively to the types from which the two types
+are derived.
+</FONT></P><P>
+<FONT size="-1"> For an identifier with external or internal linkage declared in the
+same scope as another declaration for that identifier, the type of the
+identifier becomes the composite type.
+</FONT></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> Given the following two file scope declarations:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int f(int (*)(), double (*)[3]);
+ int f(int (*)(char *), double (*)[]);
+</FONT></P></PRE><P>
+<FONT size="-1">The resulting composite type for the function is:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int f(int (*)(char *), double (*)[3]);
+</FONT></P></PRE></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ declarators (<A href="
+ #3.5.4">3.5.4</A>), enumeration specifiers
+(<A href="
+ #3.5.2.2">3.5.2.2</A>), structure and union specifiers (<A href="
+ #3.5.2.1">3.5.2.1</A>), type
+definitions (<A href="
+ #3.5.6">3.5.6</A>), type qualifiers (<A href="
+ #3.5.3">3.5.3</A>), type specifiers
+(<A href="
+ #3.5.2">3.5.2</A>).
+</FONT></P><H4><A name="3.1.3">3.1.3 Constants</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="constant">constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #floating-constant">floating-constant</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #integer-constant">integer-constant</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #enumeration-constant">enumeration-constant</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #character-constant">character-constant</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The value of a constant shall be in the range of representable
+values for its type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> Each constant has a type, determined by its form and value, as
+detailed later.
+</FONT></P></P><H5><A name="3.1.3.1">3.1.3.1 Floating constants</A></H5>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="floating-constant">floating-constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #fractional-constant">fractional-constant</A></FONT> <FONT class="nonterm"><A href="
+ #exponent-part">exponent-part</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #floating-suffix">floating-suffix</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #digit-sequence">digit-sequence</A></FONT> <FONT class="nonterm"><A href="
+ #exponent-part">exponent-part</A></FONT> <FONT class="nonterm"><A href="
+ #floating-suffix">floating-suffix</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="fractional-constant">fractional-constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #digit-sequence">digit-sequence</A><SUB>opt</SUB></FONT> <FONT class="term">.</FONT> <FONT class="nonterm"><A href="
+ #digit-sequence">digit-sequence</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #digit-sequence">digit-sequence</A></FONT> <FONT class="term">.</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="exponent-part">exponent-part</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">e</FONT> <FONT class="nonterm"><A href="
+ #sign">sign</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #digit-sequence">digit-sequence</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">E</FONT> <FONT class="nonterm"><A href="
+ #sign">sign</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #digit-sequence">digit-sequence</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="sign">sign</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">+</FONT> <FONT class="term">-</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="digit-sequence">digit-sequence</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #digit">digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #digit-sequence">digit-sequence</A></FONT> <FONT class="nonterm"><A href="
+ #digit">digit</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="floating-suffix">floating-suffix</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">f</FONT> <FONT class="term">l</FONT> <FONT class="term">F</FONT> <FONT class="term">L</FONT></P></P></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> A floating constant has a value part that may be followed by an
+exponent part and a suffix that specifies its type. The components of
+the value part may include a digit sequence representing the
+whole-number part, followed by a period (.), followed by a digit
+sequence representing the fraction part. The components of the
+exponent part are an e or E followed by an exponent consisting of an
+optionally signed digit sequence. Either the whole-number part or the
+fraction part shall be present; either the period or the exponent part
+shall be present.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The value part is interpreted as a decimal rational number; the
+digit sequence in the exponent part is interpreted as a decimal
+integer. The exponent indicates the power of 10 by which the value
+part is to be scaled. If the scaled value is in the range of
+representable values (for its type) but cannot be represented exactly,
+the result is either the nearest higher or nearest lower value, chosen
+in an implementation-defined manner.
+</FONT></P><P>
+<FONT size="-1"> An unsuffixed floating constant has type double. If suffixed by
+the letter f or F, it has type float. If suffixed by the letter l
+or L, it has type long double.
+</FONT></P></P><H5><A name="3.1.3.2">3.1.3.2 Integer constants</A></H5>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="integer-constant">integer-constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #decimal-constant">decimal-constant</A></FONT> <FONT class="nonterm"><A href="
+ #integer-suffix">integer-suffix</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #octal-constant">octal-constant</A></FONT> <FONT class="nonterm"><A href="
+ #integer-suffix">integer-suffix</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #hexadecimal-constant">hexadecimal-constant</A></FONT> <FONT class="nonterm"><A href="
+ #integer-suffix">integer-suffix</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="decimal-constant">decimal-constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #nonzero-digit">nonzero-digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #decimal-constant">decimal-constant</A></FONT> <FONT class="nonterm"><A href="
+ #digit">digit</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="octal-constant">octal-constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">0</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #octal-constant">octal-constant</A></FONT> <FONT class="nonterm"><A href="
+ #octal-digit">octal-digit</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="hexadecimal-constant">hexadecimal-constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">0x</FONT> <FONT class="nonterm"><A href="
+ #hexadecimal-digit">hexadecimal-digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">0X</FONT> <FONT class="nonterm"><A href="
+ #hexadecimal-digit">hexadecimal-digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #hexadecimal-constant">hexadecimal-constant</A></FONT> <FONT class="nonterm"><A href="
+ #hexadecimal-digit">hexadecimal-digit</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="nonzero-digit">nonzero-digit</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">1</FONT> <FONT class="term">2</FONT> <FONT class="term">3</FONT> <FONT class="term">4</FONT> <FONT class="term">5</FONT> <FONT class="term">6</FONT> <FONT class="term">7</FONT> <FONT class="term">8</FONT> <FONT class="term">9</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="octal-digit">octal-digit</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">0</FONT> <FONT class="term">1</FONT> <FONT class="term">2</FONT> <FONT class="term">3</FONT> <FONT class="term">4</FONT> <FONT class="term">5</FONT> <FONT class="term">6</FONT> <FONT class="term">7</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="hexadecimal-digit">hexadecimal-digit</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">0</FONT> <FONT class="term">1</FONT> <FONT class="term">2</FONT> <FONT class="term">3</FONT> <FONT class="term">4</FONT> <FONT class="term">5</FONT> <FONT class="term">6</FONT> <FONT class="term">7</FONT> <FONT class="term">8</FONT> <FONT class="term">9</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">a</FONT> <FONT class="term">b</FONT> <FONT class="term">c</FONT> <FONT class="term">d</FONT> <FONT class="term">e</FONT> <FONT class="term">f</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">A</FONT> <FONT class="term">B</FONT> <FONT class="term">C</FONT> <FONT class="term">D</FONT> <FONT class="term">E</FONT> <FONT class="term">F</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="integer-suffix">integer-suffix</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #unsigned-suffix">unsigned-suffix</A></FONT> <FONT class="nonterm"><A href="
+ #long-suffix">long-suffix</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #long-suffix">long-suffix</A></FONT> <FONT class="nonterm"><A href="
+ #unsigned-suffix">unsigned-suffix</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="unsigned-suffix">unsigned-suffix</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">u</FONT> <FONT class="term">U</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="long-suffix">long-suffix</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">l</FONT> <FONT class="term">L</FONT></P></P></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> An integer constant begins with a digit, but has no period or
+exponent part. It may have a prefix that specifies its base and a
+suffix that specifies its type.
+</FONT></P><P>
+<FONT size="-1"> A decimal constant begins with a nonzero digit and consists of a
+sequence of decimal digits. An octal constant consists of the prefix
+0 optionally followed by a sequence of the digits 0 through 7 only. A
+hexadecimal constant consists of the prefix 0x or 0X followed by a
+sequence of the decimal digits and the letters a (or A ) through f (or
+F) with values 10 through 15 respectively.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The value of a decimal constant is computed base 10; that of an
+octal constant, base 8; that of a hexadecimal constant, base 16. The
+lexically first digit is the most significant.
+</FONT></P><P>
+<FONT size="-1"> The type of an integer constant is the first of the corresponding
+list in which its value can be represented. Unsuffixed decimal: int,
+long int, unsigned long int; unsuffixed octal or hexadecimal: int,
+unsigned int, long int, unsigned long int; suffixed by the letter u
+or U: unsigned int, unsigned long int; suffixed by the letter l or
+L: long int, unsigned long int; suffixed by both the letters u or U
+and l or L: unsigned long int .
+</FONT></P></P><H5><A name="3.1.3.3">3.1.3.3 Enumeration constants</A></H5>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="enumeration-constant">enumeration-constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An identifier declared as an enumeration constant has type int.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ enumeration specifiers (<A href="
+ #3.5.2.2">3.5.2.2</A>).
+</FONT></P><H5><A name="3.1.3.4">3.1.3.4 Character constants</A></H5>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="character-constant">character-constant</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">'</FONT> <FONT class="nonterm"><A href="
+ #c-char-sequence">c-char-sequence</A></FONT> <FONT class="term">'</FONT> </P><P class="nonterm-defseq">
+<FONT class="term">L'</FONT> <FONT class="nonterm"><A href="
+ #c-char-sequence">c-char-sequence</A></FONT> <FONT class="term">'</FONT> </P></P><P class="syntax-def"> <FONT class="nonterm"><A name="c-char-sequence">c-char-sequence</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #c-char">c-char</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #c-char-sequence">c-char-sequence</A></FONT> <FONT class="nonterm"><A href="
+ #c-char">c-char</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="c-char">c-char</A></FONT>:<BR> <P class="regulartext-nonterm">
+<FONT size="-1">any member of the source character set except the single-quote ', backslash \, or new-line character</FONT></P> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #escape-sequence">escape-sequence</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="escape-sequence">escape-sequence</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #simple-escape-sequence">simple-escape-sequence</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #octal-escape-sequence">octal-escape-sequence</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #hexadecimal-escape-sequence">hexadecimal-escape-sequence</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="simple-escape-sequence">simple-escape-sequence</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">\'</FONT> <FONT class="term">\"</FONT> <FONT class="term">\?</FONT> <FONT class="term">\\</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">\a</FONT> <FONT class="term">\b</FONT> <FONT class="term">\f</FONT> <FONT class="term">\n</FONT> <FONT class="term">\r</FONT> <FONT class="term">\t</FONT> <FONT class="term">\v</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="octal-escape-sequence">octal-escape-sequence</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">\</FONT> <FONT class="nonterm"><A href="
+ #octal-digit">octal-digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">\</FONT> <FONT class="nonterm"><A href="
+ #octal-digit">octal-digit</A></FONT> <FONT class="nonterm"><A href="
+ #octal-digit">octal-digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">\</FONT> <FONT class="nonterm"><A href="
+ #octal-digit">octal-digit</A></FONT> <FONT class="nonterm"><A href="
+ #octal-digit">octal-digit</A></FONT> <FONT class="nonterm"><A href="
+ #octal-digit">octal-digit</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="hexadecimal-escape-sequence">hexadecimal-escape-sequence</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">\x</FONT> <FONT class="nonterm"><A href="
+ #hexadecimal-digit">hexadecimal-digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #hexadecimal-escape-sequence">hexadecimal-escape-sequence</A></FONT> <FONT class="nonterm"><A href="
+ #hexadecimal-digit">hexadecimal-digit</A></FONT></P></P></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> An integer character constant is a sequence of one or more
+multibyte characters enclosed in single-quotes, as in 'x' or 'ab'. A
+wide character constant is the same, except prefixed by the letter L .
+With a few exceptions detailed later, the elements of the sequence are
+any members of the source character set; they are mapped in an
+implementation-defined manner to members of the execution character
+set.
+</FONT></P><P>
+<FONT size="-1"> The single-quote ', the double-quote , the question-mark ?, the
+backslash \ , and arbitrary integral values, are representable
+according to the following table of escape sequences:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> single-quote ' \'
+ double-quote " \"
+ question-mark ? \?
+ backslash \ \\
+ octal integer \ octal digits
+ hexadecimal integer \x hexadecimal digits
+</FONT></P></PRE><P>
+<FONT size="-1"> The double-quote and question-mark ? are representable either by
+themselves or by the escape sequences \" and \? respectively, but the
+single-quote ' and the backslash \ shall be represented, respectively,
+by the escape sequences \' and \\ .
+</FONT></P><P>
+<FONT size="-1"> The octal digits that follow the backslash in an octal escape
+sequence are taken to be part of the construction of a single
+character for an integer character constant or of a single wide
+character for a wide character constant. The numerical value of the
+octal integer so formed specifies the value of the desired character.
+</FONT></P><P>
+<FONT size="-1"> The hexadecimal digits that follow the backslash and the letter x
+in a hexadecimal escape sequence are taken to be part of the
+construction of a single character for an integer character constant
+or of a single wide character for a wide character constant. The
+numerical value of the hexadecimal integer so formed specifies the
+value of the desired character.
+</FONT></P><P>
+<FONT size="-1"> Each octal or hexadecimal escape sequence is the longest sequence
+of characters that can constitute the escape sequence.
+</FONT></P><P>
+<FONT size="-1"> In addition, certain nongraphic characters are representable by
+escape sequences consisting of the backslash \ followed by a
+lower-case letter: \a , \b , \f , \n , \r , \t , and \v .<SUP><A href="
+ #17">17</A></SUP> If any
+other escape sequence is encountered, the behavior is undefined.<SUP><A href="
+ #18">18</A></SUP></FONT></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The value of an octal or hexadecimal escape sequence shall be in
+the range of representable values for the unsigned type corresponding
+to its type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An integer character constant has type int. The value of an
+integer character constant containing a single character that maps
+into a member of the basic execution character set is the numerical
+value of the representation of the mapped character interpreted as an
+integer. The value of an integer character constant containing more
+than one character, or containing a character or escape sequence not
+represented in the basic execution character set, is
+implementation-defined. In particular, in an implementation in which
+type char has the same range of values as signed char, the high-order
+bit position of a single-character integer character constant is
+treated as a sign bit.
+</FONT></P><P>
+<FONT size="-1"> A wide character constant has type wchar_t , an integral type
+defined in the <stddef.h> header. The value of a wide character
+constant containing a single multibyte character that maps into a
+member of the extended execution character set is the wide character
+(code) corresponding to that multibyte character, as defined by the
+mbtowc function, with an implementation-defined current locale. The
+value of a wide character constant containing more than one multibyte
+character, or containing a multibyte character or escape sequence not
+represented in the extended execution character set, is
+implementation-defined.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The construction '\0' is commonly used to represent the null character.
+</FONT></P><P>
+<FONT size="-1"> Consider implementations that use two's-complement representation
+for integers and eight bits for objects that have type char. In an
+implementation in which type char has the same range of values as
+signed char, the integer character constant '\xFF' has the value if
+type char has the same range of values as unsigned char, the
+character constant '\xFF' has the value
+</FONT></P><P>
+<FONT size="-1"> Even if eight bits are used for objects that have type char , the
+construction '\x123' specifies an integer character constant
+containing only one character. (The value of this single-character
+integer character constant is implementation-defined and violates the
+above constraint.) To specify an integer character constant containing
+the two characters whose values are 0x12 and '3', the construction
+'\0223' may be used, since a hexadecimal escape sequence is terminated
+only by a non-hexadecimal character. (The value of this two-character
+integer character constant is implementation-defined also.)
+</FONT></P><P>
+<FONT size="-1"> Even if 12 or more bits are used for objects that have type wchar_t,
+the construction L'\1234' specifies the implementation-defined value
+that results from the combination of the values 0123 and '4'.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ characters and integers (<A href="
+ #3.2.1.1">3.2.1.1</A>) common
+definitions <stddef.h> (<A href="
+ #4.1.5">4.1.5</A>), the mbtowc function (<A href="
+ #4.10.7.2">4.10.7.2</A>).
+</FONT></P>
+
+<H4><A name="3.1.4">3.1.4 String literals</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="string-literal">string-literal</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">"</FONT> <FONT class="nonterm"><A href="
+ #s-char-sequence">s-char-sequence</A><SUB>opt</SUB></FONT> <FONT class="term">"</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">L"</FONT> <FONT class="nonterm"><A href="
+ #s-char-sequence">s-char-sequence</A><SUB>opt</SUB></FONT> <FONT class="term">"</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="s-char-sequence">s-char-sequence</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #s-char">s-char</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #s-char-sequence">s-char-sequence</A></FONT> <FONT class="nonterm"><A href="
+ #s-char">s-char</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="s-char">s-char</A></FONT>:<BR> <P class="regulartext-nonterm">
+<FONT size="-1">any member of the source character set except the double-quote ", backslash \, or new-line character</FONT></P> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #escape-sequence">escape-sequence</A></FONT></P></P></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> A character string literal is a sequence of zero or more multibyte
+characters enclosed in double-quotes, as in xyz. A wide string
+literal is the same, except prefixed by the letter L.
+</FONT></P><P>
+<FONT size="-1"> The same considerations apply to each element of the sequence in a
+character string literal or a wide string literal as if it were in an
+integer character constant or a wide character constant, except that
+the single-quote ' is representable either by itself or by the escape
+sequence \', but the double-quote shall be represented by the escape
+sequence \.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A character string literal has static storage duration and type
+``array of char ,'' and is initialized with the given characters. A
+wide string literal has static storage duration and type ``array of
+wchar_t,'' and is initialized with the wide characters corresponding
+to the given multibyte characters. Character string literals that are
+adjacent tokens are concatenated into a single character string
+literal. A null character is then appended.<SUP><A href="
+ #19">19</A></SUP> Likewise, adjacent
+wide string literal tokens are concatenated into a single wide string
+literal to which a code with value zero is then appended. If a
+character string literal token is adjacent to a wide string literal
+token, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> Identical string literals of either form need not be distinct. If
+the program attempts to modify a string literal of either form, the
+behavior is undefined.
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> This pair of adjacent character string literals
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> "\x12" "3"
+</FONT></P></PRE><P>
+<FONT size="-1">produces a single character string literal containing the two
+characters whose values are \x12 and '3', because escape sequences are
+converted into single members of the execution character set just
+prior to adjacent string literal concatenation.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ common definitions <stddef.h> (<A href="
+ #4.1.5">4.1.5</A>).
+</FONT></P><H4><A name="3.1.5">3.1.5 Operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="operator">operator</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">[</FONT> <FONT class="term">]</FONT> <FONT class="term">(</FONT> <FONT class="term">)</FONT> <FONT class="term">.</FONT> <FONT class="term">-></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">++</FONT> <FONT class="term">--</FONT> <FONT class="term">&</FONT> <FONT class="term">*</FONT> <FONT class="term">+</FONT> <FONT class="term">-</FONT> <FONT class="term">~</FONT> <FONT class="term">!</FONT> <FONT class="term">sizeof</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">/</FONT> <FONT class="term">%</FONT> <FONT class="term"><<</FONT> <FONT class="term">>></FONT> <FONT class="term"><</FONT> <FONT class="term">></FONT> <FONT class="term"><=</FONT> <FONT class="term">>=</FONT> <FONT class="term">==</FONT> <FONT class="term">!=</FONT> <FONT class="term">^</FONT> <FONT class="term">|</FONT> <FONT class="term">&&</FONT> <FONT class="term">||</FONT> <FONT class="term">?</FONT> :</P><P class="nonterm-defseq">
+<FONT class="term">=</FONT> <FONT class="term">*=</FONT> <FONT class="term">/=</FONT> <FONT class="term">%=</FONT> <FONT class="term">+=</FONT> <FONT class="term">-=</FONT> <FONT class="term"><<=</FONT> <FONT class="term">>>=</FONT> <FONT class="term">&=</FONT> <FONT class="term">^=</FONT> <FONT class="term">|=</FONT> <FONT class="term">,</FONT> <FONT class="term">#</FONT> <FONT class="term">##</FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The operators [ ] , ( ) , and ? : shall occur in pairs, possibly
+separated by expressions. The operators # and ## shall occur in
+macro-defining preprocessing directives only.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An operator specifies an operation to be performed (an evaluation )
+that yields a value, or yields a designator, or produces a side
+effect, or a combination thereof. An operand is an entity on which an
+operator acts.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ expressions (<A href="
+ #3.3">3.3</A>), macro replacement (<A href="
+ #3.8.3">3.8.3</A>).
+</FONT></P><H4><A name="3.1.6">3.1.6 Punctuators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="punctuator">punctuator</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">[</FONT> <FONT class="term">]</FONT> <FONT class="term">(</FONT> <FONT class="term">)</FONT> <FONT class="term">{</FONT> <FONT class="term">}</FONT> <FONT class="term">*</FONT> <FONT class="term">,</FONT> : <FONT class="term">=</FONT> <FONT class="term">;</FONT> <FONT class="term">...</FONT> <FONT class="term">#</FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The punctuators [ ] , ( ) , and { } shall occur in pairs, possibly
+separated by expressions, declarations, or statements. The punctuator
+# shall occur in preprocessing directives only.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A punctuator is a symbol that has independent syntactic and
+semantic significance but does not specify an operation to be
+performed that yields a value. Depending on context, the same symbol
+may also represent an operator or part of an operator.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ expressions (<A href="
+ #3.3">3.3</A>), declarations (<A href="
+ #3.5">3.5</A>),
+preprocessing directives (<A href="
+ #3.8">3.8</A>), statements (<A href="
+ #3.6">3.6</A>).
+</FONT></P><H4><A name="3.1.7">3.1.7 Header names</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="header-name">header-name</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term"><</FONT> <FONT class="nonterm"><A href="
+ #h-char-sequence">h-char-sequence</A></FONT> <FONT class="term">></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">"</FONT> <FONT class="nonterm"><A href="
+ #q-char-sequence">q-char-sequence</A></FONT> <FONT class="term">"</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="h-char-sequence">h-char-sequence</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #h-char">h-char</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #h-char-sequence">h-char-sequence</A></FONT> <FONT class="nonterm"><A href="
+ #h-char">h-char</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="h-char">h-char</A></FONT>:<BR> <P class="regulartext-nonterm">
+<FONT size="-1">any member of the source character set except the new-line character and ></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="q-char-sequence">q-char-sequence</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #q-char">q-char</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #q-char-sequence">q-char-sequence</A></FONT> <FONT class="nonterm"><A href="
+ #q-char">q-char</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="q-char">q-char</A></FONT>:<BR> <P class="regulartext-nonterm">
+<FONT size="-1">any member of the source character set except the new-line character and "</FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Header name preprocessing tokens shall only appear within a
+#include preprocessing directive.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The sequences in both forms of header names are mapped in an
+implementation-defined manner to headers or external source file names
+as specified in <A href="
+ #3.8.2">3.8.2</A></FONT></P><P>
+<FONT size="-1"> If the characters ', \ , , or /* occur in the sequence between the
+< and > delimiters, the behavior is undefined. Similarly, if the
+characters ', \ , or /* occur in the sequence between the " delimiters,
+the behavior is undefined.<SUP><A href="
+ #20">20</A></SUP></FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> The following sequence of characters:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> 0x3<1/a.h>1e2
+ #include <1/a.h>
+ #define const.member@$
+</FONT></P></PRE><P>
+<FONT size="-1">forms the following sequence of preprocessing tokens (with each
+individual preprocessing token delimited by a { on the left and a } on
+the right).
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> {0x3}{<}{1}{/}{a}{.}{h}{>}{1e2}
+ {#}{include} {<1/a.h>}
+ {#}{define} {const}{.}{member}{@}{$}
+</FONT></P></PRE></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ source file inclusion (<A href="
+ #3.8.2">3.8.2</A>).
+</FONT></P><H4><A name="3.1.8">3.1.8 Preprocessing numbers</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="pp-number">pp-number</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #digit">digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">.</FONT> <FONT class="nonterm"><A href="
+ #digit">digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-number">pp-number</A></FONT> <FONT class="nonterm"><A href="
+ #digit">digit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-number">pp-number</A></FONT> <FONT class="nonterm"><A href="
+ #nondigit">nondigit</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-number">pp-number</A></FONT> <FONT class="term">e</FONT> <FONT class="nonterm"><A href="
+ #sign">sign</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-number">pp-number</A></FONT> <FONT class="term">E</FONT> <FONT class="nonterm"><A href="
+ #sign">sign</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-number">pp-number</A></FONT> <FONT class="term">.</FONT></P></P></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> A preprocessing number begins with a digit optionally preceded by a
+period (.) and may be followed by letters, underscores, digits,
+periods, and e+, e-, E+, or E- character sequences.
+</FONT></P><P>
+<FONT size="-1"> Preprocessing number tokens lexically include all floating and
+integer constant tokens.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A preprocessing number does not have type or a value; it acquires
+both after a successful conversion (as part of translation phase 7) to
+a floating constant token or an integer constant token.
+</FONT></P></P><H4><A name="3.1.9">3.1.9 Comments</A></H4>
+<P>
+<FONT size="-1"> Except within a character constant, a string literal, or a comment,
+the characters /* introduce a comment. The contents of a comment are
+examined only to identify multibyte characters and to find the
+characters */ that terminate it.<SUP><A href="
+ #21">21</A></SUP></FONT></P><H3><A name="3.2">3.2 CONVERSIONS</A></H3>
+<P>
+<FONT size="-1"> Several operators convert operand values from one type to another
+automatically. This section specifies the result required from such
+an implicit conversion, as well as those that result from a cast
+operation (an explicit conversion). The list in <A href="
+ #3.2.1.5">3.2.1.5</A> summarizes
+the conversions performed by most ordinary operators; it is
+supplemented as required by the discussion of each operator in <A href="
+ #3.3">3.3</A></FONT></P><P>
+<FONT size="-1"> Conversion of an operand value to a compatible type causes no change.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ cast operators (<A href="
+ #3.3.4">3.3.4</A>).
+</FONT></P><H4><A name="3.2.1">3.2.1 Arithmetic operands</A></H4>
+<H5><A name="3.2.1.1">3.2.1.1 Characters and integers</A></H5>
+<P>
+<FONT size="-1"> A char, a short int, or an int bit-field, or their signed or
+unsigned varieties, or an object that has enumeration type, may be
+used in an expression wherever an int or unsigned int may be used. If
+an int can represent all values of the original type, the value is
+converted to an int; otherwise it is converted to an unsigned int.
+These are called the integral promotions.
+</FONT></P><P>
+<FONT size="-1"> The integral promotions preserve value including sign. As
+discussed earlier, whether a ``plain'' char is treated as signed is
+implementation-defined.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ enumeration specifiers (<A href="
+ #3.5.2.2">3.5.2.2</A>), structure and
+union specifiers (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P><H5><A name="3.2.1.2">3.2.1.2 Signed and unsigned integers</A></H5>
+<P>
+<FONT size="-1"> When an unsigned integer is converted to another integral type, if
+the value can be represented by the new type, its value is unchanged.
+</FONT></P><P>
+<FONT size="-1"> When a signed integer is converted to an unsigned integer with
+equal or greater size, if the value of the signed integer is
+nonnegative, its value is unchanged. Otherwise: if the unsigned
+integer has greater size, the signed integer is first promoted to the
+signed integer corresponding to the unsigned integer; the value is
+converted to unsigned by adding to it one greater than the largest
+number that can be represented in the unsigned integer type.<SUP><A href="
+ #22">22</A></SUP></FONT></P><P>
+<FONT size="-1"> When an integer is demoted to an unsigned integer with smaller
+size, the result is the nonnegative remainder on division by the
+number one greater than the largest unsigned number that can be
+represented in the type with smaller size. When an integer is demoted
+to a signed integer with smaller size, or an unsigned integer is
+converted to its corresponding signed integer, if the value cannot be
+represented the result is implementation-defined.
+</FONT></P><H5><A name="3.2.1.3">3.2.1.3 Floating and integral</A></H5>
+<P>
+<FONT size="-1"> When a value of floating type is converted to integral type, the
+fractional part is discarded. If the value of the integral part
+cannot be represented by the integral type, the behavior is
+undefined.<SUP><A href="
+ #23">23</A></SUP></FONT></P><P>
+<FONT size="-1"> When a value of integral type is converted to floating type, if the
+value being converted is in the range of values that can be
+represented but cannot be represented exactly, the result is either
+the nearest higher or nearest lower value, chosen in an
+implementation-defined manner.
+</FONT></P><H5><A name="3.2.1.4">3.2.1.4 Floating types</A></H5>
+<P>
+<FONT size="-1"> When a float is promoted to double or long double , or a double is
+promoted to long double , its value is unchanged.
+</FONT></P><P>
+<FONT size="-1"> When a double is demoted to float or a long double to double or
+float, if the value being converted is outside the range of values
+that can be represented, the behavior is undefined. If the value
+being converted is in the range of values that can be represented but
+cannot be represented exactly, the result is either the nearest higher
+or nearest lower value, chosen in an implementation-defined manner.
+</FONT></P><H5><A name="3.2.1.5">3.2.1.5 Usual arithmetic conversions</A></H5>
+<P>
+<FONT size="-1"> Many binary operators that expect operands of arithmetic type cause
+conversions and yield result types in a similar way. The purpose is
+to yield a common type, which is also the type of the result. This
+pattern is called the usual arithmetic conversions: First, if either
+operand has type long double, the other operand is converted to long
+double . Otherwise, if either operand has type double, the other
+operand is converted to double. Otherwise, if either operand has
+type float, the other operand is converted to float. Otherwise, the
+integral promotions are performed on both operands. Then the
+following rules are applied: If either operand has type unsigned long
+int, the other operand is converted to unsigned long int.
+Otherwise, if one operand has type long int and the other has type
+unsigned int, if a long int can represent all values of an unsigned
+int, the operand of type unsigned int is converted to long int ; if a
+long int cannot represent all the values of an unsigned int, both
+operands are converted to unsigned long int. Otherwise, if either
+operand has type long int, the other operand is converted to long int.
+Otherwise, if either operand has type unsigned int, the other
+operand is converted to unsigned int. Otherwise, both operands have
+type int.
+</FONT></P><P>
+<FONT size="-1"> The values of operands and of the results of expressions may be
+represented in greater precision and range than that required by the
+type; the types are not changed thereby.
+</FONT></P><H4><A name="3.2.2">3.2.2 Other operands</A></H4>
+<H5><A name="3.2.2.1">3.2.2.1 Lvalues and function designators</A></H5>
+<P>
+<FONT size="-1"> An lvalue is an expression (with an object type or an incomplete
+type other than void) that designates an object.<SUP><A href="
+ #24">24</A></SUP> When an object
+is said to have a particular type, the type is specified by the lvalue
+used to designate the object. A modifiable lvalue is an lvalue that
+does not have array type, does not have an incomplete type, does not
+have a const-qualified type, and if it is a structure or union, does
+not have any member (including, recursively, any member of all
+contained structures or unions) with a const-qualified type.
+</FONT></P><P>
+<FONT size="-1"> Except when it is the operand of the sizeof operator, the unary &
+operator, the ++ operator, the -- operator, or the left operand of the .
+operator or an assignment operator, an lvalue that does not have
+array type is converted to the value stored in the designated object
+(and is no longer an lvalue). If the lvalue has qualified type, the
+value has the unqualified version of the type of the lvalue; otherwise
+the value has the type of the lvalue. If the lvalue has an incomplete
+type and does not have array type, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> Except when it is the operand of the sizeof operator or the unary &
+operator, or is a character string literal used to initialize an array
+of character type, or is a wide string literal used to initialize an
+array with element type compatible with wchar_t, an lvalue that has
+type ``array of type '' is converted to an expression that has type
+``pointer to type '' that points to the initial member of the array
+object and is not an lvalue.
+</FONT></P><P>
+<FONT size="-1"> A function designator is an expression that has function type.
+Except when it is the operand of the sizeof operator<SUP><A href="
+ #25">25</A></SUP> or the unary
+& operator, a function designator with type ``function returning type
+'' is converted to an expression that has type ``pointer to function
+returning type .''
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ address and indirection operators (<A href="
+ #3.3.3.2">3.3.3.2</A>),
+assignment operators (<A href="
+ #3.3.16">3.3.16</A>), common definitions <stddef.h>
+(<A href="
+ #4.1.5">4.1.5</A>), initialization (<A href="
+ #3.5.7">3.5.7</A>), postfix increment and decrement
+operators (<A href="
+ #3.3.2.4">3.3.2.4</A>), prefix increment and decrement operators
+(<A href="
+ #3.3.3.1">3.3.3.1</A>), the sizeof operator (<A href="
+ #3.3.3.4">3.3.3.4</A>), structure and union
+members (<A href="
+ #3.3.2.3">3.3.2.3</A>).
+</FONT></P><H5><A name="3.2.2.2">3.2.2.2 void</A></H5>
+<P>
+<FONT size="-1"> The (nonexistent) value of a void expression (an expression that
+has type void) shall not be used in any way, and implicit or explicit
+conversions (except to void ) shall not be applied to such an
+expression. If an expression of any other type occurs in a context
+where a void expression is required, its value or designator is
+discarded. (A void expression is evaluated for its side effects.)
+</FONT></P><H5><A name="3.2.2.3">3.2.2.3 Pointers</A></H5>
+<P>
+<FONT size="-1"> A pointer to void may be converted to or from a pointer to any
+incomplete or object type. A pointer to any incomplete or object type
+may be converted to a pointer to void and back again; the result shall
+compare equal to the original pointer.
+</FONT></P><P>
+<FONT size="-1"> A pointer to a non-q-qualified type may be converted to a pointer
+to the q-qualified version of the type; the values stored in the
+original and converted pointers shall compare equal.
+</FONT></P><P>
+<FONT size="-1"> An integral constant expression with the value 0, or such an
+expression cast to type void * , is called a null pointer constant. If
+a null pointer constant is assigned to or compared for equality to a
+pointer, the constant is converted to a pointer of that type. Such a
+pointer, called a null pointer, is guaranteed to compare unequal to a
+pointer to any object or function.
+</FONT></P><P>
+<FONT size="-1"> Two null pointers, converted through possibly different sequences
+of casts to pointer types, shall compare equal.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ cast operators (<A href="
+ #3.3.4">3.3.4</A>), equality operators
+(<A href="
+ #3.3.9">3.3.9</A>), simple assignment (<A href="
+ #3.3.16.1">3.3.16.1</A>).
+</FONT></P><H3><A name="3.3">3.3 EXPRESSIONS</A></H3>
+<P>
+<FONT size="-1"> An expression is a sequence of operators and operands that
+specifies computation of a value, or that designates an object or a
+function, or that generates side effects, or that performs a
+combination thereof.
+</FONT></P><P>
+<FONT size="-1"> Between the previous and next sequence point an object shall have
+its stored value modified at most once by the evaluation of an
+expression. Furthermore, the prior value shall be accessed only to
+determine the value to be stored.<SUP><A href="
+ #26">26</A></SUP></FONT></P><P>
+<FONT size="-1"> Except as indicated by the syntax<SUP><A href="
+ #27">27</A></SUP> or otherwise specified later
+(for the function-call operator () , && , || , ?: , and comma
+operators), the order of evaluation of subexpressions and the order in
+which side effects take place are both unspecified.
+</FONT></P><P>
+<FONT size="-1"> Some operators (the unary operator ~ , and the binary operators << ,
+>> , & , ^ , and | , collectively described as bitwise operators
+)shall have operands that have integral type. These operators return
+values that depend on the internal representations of integers, and
+thus have implementation-defined aspects for signed types.
+</FONT></P><P>
+<FONT size="-1"> If an exception occurs during the evaluation of an expression (that
+is, if the result is not mathematically defined or not representable),
+the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> An object shall have its stored value accessed only by an lvalue
+that has one of the following types:<SUP><A href="
+ #28">28</A></SUP></FONT></P><P>
+<FONT size="-1"> * the declared type of the object,
+</FONT></P><P>
+<FONT size="-1"> * a qualified version of the declared type of the object,
+</FONT></P><P>
+<FONT size="-1"> * a type that is the signed or unsigned type corresponding to the
+ declared type of the object,
+</FONT></P><P>
+<FONT size="-1"> * a type that is the signed or unsigned type corresponding to a
+ qualified version of the declared type of the object,
+</FONT></P><P>
+<FONT size="-1"> * an aggregate or union type that includes one of the aforementioned
+ types among its members (including, recursively, a member of a
+ subaggregate or contained union), or
+</FONT></P><P>
+<FONT size="-1"> * a character type.
+</FONT></P><H4><A name="3.3.1">3.3.1 Primary expressions</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="primary-expression">primary-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #constant">constant</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #string-literal">string-literal</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> <FONT class="term">)</FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An identifier is a primary expression, provided it has been
+declared as designating an object (in which case it is an lvalue) or a
+function (in which case it is a function designator).
+</FONT></P><P>
+<FONT size="-1"> A constant is a primary expression. Its type depends on its form,
+as detailed in <A href="
+ #3.1.3">3.1.3</A></FONT></P><P>
+<FONT size="-1"> A string literal is a primary expression. It is an lvalue with
+type as detailed in <A href="
+ #3.1.4">3.1.4</A></FONT></P><P>
+<FONT size="-1"> A parenthesized expression is a primary expression. Its type and
+value are identical to those of the unparenthesized expression. It is
+an lvalue, a function designator, or a void expression if the
+unparenthesized expression is, respectively, an lvalue, a function
+designator, or a void expression.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ declarations (<A href="
+ #3.5">3.5</A>).
+</FONT></P><H4><A name="3.3.2">3.3.2 Postfix operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="postfix-expression">postfix-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #primary-expression">primary-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #postfix-expression">postfix-expression</A></FONT> <FONT class="term">[</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> <FONT class="term">]</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #postfix-expression">postfix-expression</A></FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #argument-expression-list">argument-expression-list</A><SUB>opt</SUB></FONT> <FONT class="term">)</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #postfix-expression">postfix-expression</A></FONT> <FONT class="term">.</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #postfix-expression">postfix-expression</A></FONT> <FONT class="term">-></FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #postfix-expression">postfix-expression</A></FONT> <FONT class="term">++</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #postfix-expression">postfix-expression</A></FONT> <FONT class="term">--</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="argument-expression-list">argument-expression-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #assignment-expression">assignment-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #argument-expression-list">argument-expression-list</A></FONT> <FONT class="term">,</FONT> <FONT class="nonterm"><A href="
+ #assignment-expression">assignment-expression</A></FONT></P></P></P><H5><A name="3.3.2.1">3.3.2.1 Array subscripting</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> One of the expressions shall have type ``pointer to object type ,''
+the other expression shall have integral type, and the result has type
+`` type .''
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A postfix expression followed by an expression in square brackets
+[] is a subscripted designation of a member of an array object. The
+definition of the subscript operator [] is that E1[E2] is identical to
+(*(E1+(E2))) . Because of the conversion rules that apply to the
+binary + operator, if E1 is an array object (equivalently, a pointer
+to the initial member of an array object) and E2 is an integer, E1[E2]
+designates the E2 -th member of E1 (counting from zero).
+</FONT></P><P>
+<FONT size="-1"> Successive subscript operators designate a member of a
+multi-dimensional array object. If E is an n -dimensional array ( n
+>=2) with dimensions i x j "x ... x" k , then E (used as other than an
+lvalue) is converted to a pointer to an ( n -1)-dimensional array with
+dimensions j "x ... x" k . If the unary * operator is applied to this
+pointer explicitly, or implicitly as a result of subscripting, the
+result is the pointed-to ( n -1)-dimensional array, which itself is
+converted into a pointer if used as other than an lvalue. It follows
+from this that arrays are stored in row-major order (last subscript
+varies fastest).
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> Consider the array object defined by the declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int x[3][5];
+</FONT></P></PRE><P>
+<FONT size="-1">Here x is a 3x5 array of int s; more precisely, x is an array of three
+member objects, each of which is an array of five int s. In the
+expression x[i] , which is equivalent to (*(x+(i))) , x is first
+converted to a pointer to the initial array of five int s. Then i is
+adjusted according to the type of x , which conceptually entails
+multiplying i by the size of the object to which the pointer points,
+namely an array of five int objects. The results are added and
+indirection is applied to yield an array of five int s. When used in
+the expression x[i][j] , that in turn is converted to a pointer to the
+first of the int s, so x[i][j] yields an int.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ additive operators (<A href="
+ #3.3.6">3.3.6</A>), address and
+indirection operators (<A href="
+ #3.3.3.2">3.3.3.2</A>), array declarators (<A href="
+ #3.5.4.2">3.5.4.2</A>).
+</FONT></P><H5><A name="3.3.2.2">3.3.2.2 Function calls</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The expression that denotes the called function<SUP><A href="
+ #29">29</A></SUP> shall have type
+pointer to function returning void or returning an object type other
+than array.
+</FONT></P><P>
+<FONT size="-1"> If the expression that denotes the called function has a type that
+includes a prototype, the number of arguments shall agree with the
+number of parameters. Each argument shall have a type such that its
+value may be assigned to an object with the unqualified version of the
+type of its corresponding parameter.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A postfix expression followed by parentheses () containing a
+possibly empty, comma-separated list of expressions is a function
+call. The postfix expression denotes the called function. The list
+of expressions specifies the arguments to the function.
+</FONT></P><P>
+<FONT size="-1"> If the expression that precedes the parenthesized argument list in
+a function call consists solely of an identifier, and if no
+declaration is visible for this identifier, the identifier is
+implicitly declared exactly as if, in the innermost block containing
+the function call, the declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> extern int identifier();
+</FONT></P></PRE><P>
+<FONT size="-1">appeared.<SUP><A href="
+ #30">30</A></SUP></FONT></P><P>
+<FONT size="-1"> An argument may be an expression of any object type. In preparing
+for the call to a function, the arguments are evaluated, and each
+parameter is assigned the value of the corresponding argument.<SUP><A href="
+ #31">31</A></SUP> The
+value of the function call expression is specified in <A href="
+ #3.6.6.4">3.6.6.4</A></FONT></P><P>
+<FONT size="-1"> If the expression that denotes the called function has a type that
+does not include a prototype, the integral promotions are performed on
+each argument and arguments that have type float are promoted to
+double. These are called the default argument promotions. If the
+number of arguments does not agree with the number of parameters, the
+behavior is undefined. If the function is defined with a type that
+does not include a prototype, and the types of the arguments after
+promotion are not compatible with those of the parameters after
+promotion, the behavior is undefined. If the function is defined with
+a type that includes a prototype, and the types of the arguments after
+promotion are not compatible with the types of the parameters, or if
+the prototype ends with an ellipsis ( ", ..." ), the behavior is
+undefined.
+</FONT></P><P>
+<FONT size="-1"> If the expression that denotes the called function has a type that
+includes a prototype, the arguments are implicitly converted, as if by
+assignment, to the types of the corresponding parameters. The
+ellipsis notation in a function prototype declarator causes argument
+type conversion to stop after the last declared parameter. The
+default argument promotions are performed on trailing arguments. If
+the function is defined with a type that is not compatible with the
+type (of the expression) pointed to by the expression that denotes the
+called function, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> No other conversions are performed implicitly; in particular, the
+number and types of arguments are not compared with those of the
+parameters in a function definition that does not include a function
+prototype declarator.
+</FONT></P><P>
+<FONT size="-1"> The order of evaluation of the function designator, the arguments,
+and subexpressions within the arguments is unspecified, but there is a
+sequence point before the actual call.
+</FONT></P><P>
+<FONT size="-1"> Recursive function calls shall be permitted, both directly and
+indirectly through any chain of other functions.
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> In the function call
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> (*pf[f1()]) (f2(), f3() + f4())
+</FONT></P></PRE><P>
+<FONT size="-1">the functions f1 , f2 , f3 , and f4 may be called in any order. All
+side effects shall be completed before the function pointed to by
+pf[f1()] is entered.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ function declarators (including prototypes)
+(<A href="
+ #3.5.4.3">3.5.4.3</A>), function definitions (<A href="
+ #3.7.1">3.7.1</A>), the return statement
+(<A href="
+ #3.6.6.4">3.6.6.4</A>), simple assignment (<A href="
+ #3.3.16.1">3.3.16.1</A>).
+</FONT></P><H5><A name="3.3.2.3">3.3.2.3 Structure and union members</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The first operand of the . operator shall have a qualified or
+unqualified structure or union type, and the second operand shall name
+a member of that type.
+</FONT></P><P>
+<FONT size="-1"> The first operand of the -> operator shall have type ``pointer to
+qualified or unqualified structure'' or ``pointer to qualified or
+unqualified union,'' and the second operand shall name a member of the
+type pointed to.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A postfix expression followed by a dot . and an identifier
+designates a member of a structure or union object. The value is that
+of the named member, and is an lvalue if the first expression is an
+lvalue. If the first expression has qualified type, the result has
+the so-qualified version of the type of the designated member.
+</FONT></P><P>
+<FONT size="-1"> A postfix expression followed by an arrow -> and an identifier
+designates a member of a structure or union object. The value is that
+of the named member of the object to which the first expression
+points, and is an lvalue.<SUP><A href="
+ #32">32</A></SUP> If the first expression is a pointer to
+a qualified type, the result has the so-qualified version of the type
+of the designated member.
+</FONT></P><P>
+<FONT size="-1"> With one exception, if a member of a union object is accessed after
+a value has been stored in a different member of the object, the
+behavior is implementation-defined.<SUP><A href="
+ #33">33</A></SUP> One special guarantee is made
+in order to simplify the use of unions: If a union contains several
+structures that share a common initial sequence, and if the union
+object currently contains one of these structures, it is permitted to
+inspect the common initial part of any of them. Two structures share
+a common initial sequence if corresponding members have compatible
+types for a sequence of one or more initial members.
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> If f is a function returning a structure or union, and x is a
+member of that structure or union, f().x is a valid postfix expression
+but is not an lvalue.
+</FONT></P><P>
+<FONT size="-1"> The following is a valid fragment:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> union {
+ struct {
+ int alltypes;
+ } n;
+ struct {
+ int type;
+ int intnode;
+ } ni;
+ struct {
+ int type;
+ double doublenode;
+ } nf;
+ } u;
+ /*...*/
+ u.nf.type = 1;
+ u.nf.doublenode = 3.14;
+ /*...*/
+ if (u.n.alltypes == 1)
+ /*...*/ sin(u.nf.doublenode) /*...*/
+</FONT></P></PRE></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ address and indirection operators (<A href="
+ #3.3.3.2">3.3.3.2</A>),
+structure and union specifiers (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P>
+
+<H5><A name="3.3.2.4">3.3.2.4 Postfix increment and decrement operators</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The operand of the postfix increment or decrement operator shall
+have qualified or unqualified scalar type and shall be a modifiable
+lvalue.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The result of the postfix ++ operator is the value of the operand.
+After the result is obtained, the value of the operand is incremented.
+(That is, the value 1 of the appropriate type is added to it.) See the
+discussions of additive operators and compound assignment for
+information on constraints, types and conversions and the effects of
+operations on pointers. The side effect of updating the stored value
+of the operand shall occur between the previous and the next sequence
+point.
+</FONT></P><P>
+<FONT size="-1"> The postfix -- operator is analogous to the postfix ++ operator,
+except that the value of the operand is decremented (that is, the
+value 1 of the appropriate type is subtracted from it).
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ additive operators (<A href="
+ #3.3.6">3.3.6</A>), compound assignment
+(<A href="
+ #3.3.16.2">3.3.16.2</A>).
+</FONT></P><H4><A name="3.3.3">3.3.3 Unary operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="unary-expression">unary-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #postfix-expression">postfix-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">++</FONT> <FONT class="nonterm"><A href="
+ #unary-expression">unary-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">--</FONT> <FONT class="nonterm"><A href="
+ #unary-expression">unary-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #unary-operator">unary-operator</A></FONT> <FONT class="nonterm"><A href="
+ #cast-expression">cast-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">sizeof</FONT> <FONT class="nonterm"><A href="
+ #unary-expression">unary-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">sizeof</FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #type-name">type-name</A></FONT> <FONT class="term">)</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="unary-operator">unary-operator</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">&</FONT> <FONT class="term">*</FONT> <FONT class="term">+</FONT> <FONT class="term">-</FONT> <FONT class="term">~</FONT> <FONT class="term">!</FONT></P></P></P><H5><A name="3.3.3.1">3.3.3.1 Prefix increment and decrement operators</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The operand of the prefix increment or decrement operator shall
+have qualified or unqualified scalar type and shall be a modifiable
+lvalue.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The value of the operand of the prefix ++ operator is incremented.
+The result is the new value of the operand after incrementation. The
+expression ++E is equivalent to (E+=1) . See the discussions of
+additive operators and compound assignment for information on
+constraints, types, side effects, and conversions and the effects of
+operations on pointers.
+</FONT></P><P>
+<FONT size="-1"> The prefix -- operator is analogous to the prefix ++ operator,
+except that the value of the operand is decremented.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ additive operators (<A href="
+ #3.3.6">3.3.6</A>), compound assignment
+(<A href="
+ #3.3.16.2">3.3.16.2</A>).
+</FONT></P><H5><A name="3.3.3.2">3.3.3.2 Address and indirection operators</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The operand of the unary & operator shall be either a function
+designator or an lvalue that designates an object that is not a
+bit-field and is not declared with the register storage-class
+specifier.
+</FONT></P><P>
+<FONT size="-1"> The operand of the unary * operator shall have pointer type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The result of the unary & (address-of) operator is a pointer to the
+object or function designated by its operand. If the operand has type
+`` type ,'' the result has type ``pointer to type .''
+</FONT></P><P>
+<FONT size="-1"> The unary * operator denotes indirection. If the operand points to
+a function, the result is a function designator; if it points to an
+object, the result is an lvalue designating the object. If the
+operand has type ``pointer to type ,'' the result has type `` type .''
+If an invalid value has been assigned to the pointer, the behavior of
+the unary * operator is undefined.<SUP><A href="
+ #34">34</A></SUP></FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ storage-class specifiers (<A href="
+ #3.5.1">3.5.1</A>), structure and
+union specifiers (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P><H5><A name="3.3.3.3">3.3.3.3 Unary arithmetic operators</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The operand of the unary + or - operator shall have arithmetic
+type; of the ~ operator, integral type; of the ! operator, scalar
+type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The result of the unary + operator is the value of its operand.
+The integral promotion is performed on the operand, and the result has
+the promoted type.
+</FONT></P><P>
+<FONT size="-1"> The result of the unary - operator is the negative of its operand.
+The integral promotion is performed on the operand, and the result has
+the promoted type.
+</FONT></P><P>
+<FONT size="-1"> The result of the ~ operator is the bitwise complement of its
+operand (that is, each bit in the result is set if and only if the
+corresponding bit in the converted operand is not set). The integral
+promotion is performed on the operand, and the result has the promoted
+type. The expression ~E is equivalent to (ULONG_MAX-E) if E is
+promoted to type unsigned long , to (UINT_MAX-E) if E is promoted to
+type unsigned int . (The constants ULONG_MAX and UINT_MAX are defined
+in the header <limits.h> .)
+</FONT></P><P>
+<FONT size="-1"> The result of the logical negation operator ! is 0 if the value of
+its operand compares unequal to 0, 1 if the value of its operand
+compares equal to 0. The result has type int . The expression !E is
+equivalent to (0==E) .
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ limits <float.h> and <limits.h> (<A href="
+ #4.1.4">4.1.4</A>).
+</FONT></P><H5><A name="3.3.3.4">3.3.3.4 The sizeof operator</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The sizeof operator shall not be applied to an expression that has
+function type or an incomplete type, to the parenthesized name of such
+a type, or to an lvalue that designates a bit-field object.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The sizeof operator yields the size (in bytes) of its operand,
+which may be an expression or the parenthesized name of a type. The
+size is determined from the type of the operand, which is not itself
+evaluated. The result is an integer constant.
+</FONT></P><P>
+<FONT size="-1"> When applied to an operand that has type char , unsigned char , or
+signed char , (or a qualified version thereof) the result is 1. When
+applied to an operand that has array type, the result is the total
+number of bytes in the array.<SUP><A href="
+ #35">35</A></SUP> When applied to an operand that has
+structure or union type, the result is the total number of bytes in
+such an object, including internal and trailing padding.
+</FONT></P><P>
+<FONT size="-1"> The value of the result is implementation-defined, and its type (an
+unsigned integral type) is size_t defined in the <stddef.h> header.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> A principal use of the sizeof operator is in communication with
+routines such as storage allocators and I/O systems. A
+storage-allocation function might accept a size (in bytes) of an
+object to allocate and return a pointer to void. For example:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> extern void *alloc();
+ double *dp = alloc(sizeof *dp);
+</FONT></P></PRE><P>
+<FONT size="-1">The implementation of the alloc function should ensure that its return
+value is aligned suitably for conversion to a pointer to double.
+</FONT></P><P>
+<FONT size="-1"> Another use of the sizeof operator is to compute the number of
+members in an array:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> sizeof array / sizeof array[0]
+</FONT></P></PRE></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ common definitions <stddef.h> (<A href="
+ #4.1.5">4.1.5</A>),
+declarations (<A href="
+ #3.5">3.5</A>), structure and union specifiers (<A href="
+ #3.5.2.1">3.5.2.1</A>), type
+names (<A href="
+ #3.5.5">3.5.5</A>).
+</FONT></P><H4><A name="3.3.4">3.3.4 Cast operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="cast-expression">cast-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #unary-expression">unary-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #type-name">type-name</A></FONT> <FONT class="term">)</FONT> <FONT class="nonterm"><A href="
+ #cast-expression">cast-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Unless the type name specifies void type, the type name shall
+specify qualified or unqualified scalar type and the operand shall
+have scalar type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> Preceding an expression by a parenthesized type name converts the
+value of the expression to the named type. This construction is
+called a cast.<SUP><A href="
+ #36">36</A></SUP> A cast that specifies an implicit conversion or no
+conversion has no effect on the type or value of an expression.
+</FONT></P><P>
+<FONT size="-1"> Conversions that involve pointers (other than as permitted by the
+constraints of <A href="
+ #3.3.16.1">3.3.16.1</A>) shall be specified by means of an explicit
+cast; they have implementation-defined aspects: A pointer may be
+converted to an integral type. The size of integer required and the
+result are implementation-defined. If the space provided is not long
+enough, the behavior is undefined. An arbitrary integer may be
+converted to a pointer. The result is implementation-defined.<SUP><A href="
+ #37">37</A></SUP> A
+pointer to an object or incomplete type may be converted to a pointer
+to a different object type or a different incomplete type. The
+resulting pointer might not be valid if it is improperly aligned for
+the type pointed to. It is guaranteed, however, that a pointer to an
+object of a given alignment may be converted to a pointer to an object
+of the same alignment or a less strict alignment and back again; the
+result shall compare equal to the original pointer. (An object that
+has character type has the least strict alignment.) A pointer to a
+function of one type may be converted to a pointer to a function of
+another type and back again; the result shall compare equal to the
+original pointer. If a converted pointer is used to call a function
+that has a type that is not compatible with the type of the called
+function, the behavior is undefined.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ equality operators (<A href="
+ #3.3.9">3.3.9</A>), function declarators
+(including prototypes) (<A href="
+ #3.5.4.3">3.5.4.3</A>), simple assignment (<A href="
+ #3.3.16.1">3.3.16.1</A>), type
+names (<A href="
+ #3.5.5">3.5.5</A>).
+</FONT></P><H4><A name="3.3.5">3.3.5 Multiplicative operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="multiplicative-expression">multiplicative-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #cast-expression">cast-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #multiplicative-expression">multiplicative-expression</A></FONT> <FONT class="term">*</FONT> <FONT class="nonterm"><A href="
+ #cast-expression">cast-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #multiplicative-expression">multiplicative-expression</A></FONT> <FONT class="term">/</FONT> <FONT class="nonterm"><A href="
+ #cast-expression">cast-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #multiplicative-expression">multiplicative-expression</A></FONT> <FONT class="term">%</FONT> <FONT class="nonterm"><A href="
+ #cast-expression">cast-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each of the operands shall have arithmetic type. The operands of
+the % operator shall have integral type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The usual arithmetic conversions are performed on the operands.
+</FONT></P><P>
+<FONT size="-1"> The result of the binary * operator is the product of the operands.
+</FONT></P><P>
+<FONT size="-1"> The result of the / operator is the quotient from the division of
+the first operand by the second; the result of the % operator is the
+remainder. In both operations, if the value of the second operand is
+zero, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> When integers are divided and the division is inexact, if both
+operands are positive the result of the / operator is the largest
+integer less than the algebraic quotient and the result of the %
+operator is positive. If either operand is negative, whether the
+result of the / operator is the largest integer less than the
+algebraic quotient or the smallest integer greater than the algebraic
+quotient is implementation-defined, as is the sign of the result of
+the % operator. If the quotient a/b is representable, the expression
+(a/b)*b + a%b shall equal a .
+</FONT></P></P><H4><A name="3.3.6">3.3.6 Additive operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="additive-expression">additive-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #multiplicative-expression">multiplicative-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #additive-expression">additive-expression</A></FONT> <FONT class="term">+</FONT> <FONT class="nonterm"><A href="
+ #multiplicative-expression">multiplicative-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #additive-expression">additive-expression</A></FONT> <FONT class="term">-</FONT> <FONT class="nonterm"><A href="
+ #multiplicative-expression">multiplicative-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> For addition, either both operands shall have arithmetic type, or
+one operand shall be a pointer to an object type and the other shall
+have integral type. (Incrementing is equivalent to adding 1.)
+</FONT></P><P>
+<FONT size="-1"> For subtraction, one of the following shall hold:
+</FONT></P><P>
+<FONT size="-1"> * both operands have arithmetic type;
+</FONT></P><P>
+<FONT size="-1"> * both operands are pointers to qualified or unqualified versions of
+ compatible object types; or
+</FONT></P><P>
+<FONT size="-1"> * the left operand is a pointer to an object type and the right
+ operand has integral type. (Decrementing is equivalent to subtracting 1.)
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> If both operands have arithmetic type, the usual arithmetic
+conversions are performed on them.
+</FONT></P><P>
+<FONT size="-1"> The result of the binary + operator is the sum of the operands.
+</FONT></P><P>
+<FONT size="-1"> The result of the binary - operator is the difference resulting
+from the subtraction of the second operand from the first.
+</FONT></P><P>
+<FONT size="-1"> When an expression that has integral type is added to or subtracted
+from a pointer, the integral value is first multiplied by the size of
+the object pointed to. The result has the type of the pointer
+operand. If the pointer operand points to a member of an array
+object, and the array object is large enough, the result points to a
+member of the same array object, appropriately offset from the
+original member. Thus if P points to a member of an array object, the
+expression P+1 points to the next member of the array object. Unless
+both the pointer operand and the result point to a member of the same
+array object, or one past the last member of the array object, the
+behavior is undefined. Unless both the pointer operand and the result
+point to a member of the same array object, or the pointer operand
+points one past the last member of an array object and the result
+points to a member of the same array object, the behavior is undefined
+if the result is used as the operand of a unary * operator.
+</FONT></P><P>
+<FONT size="-1"> When two pointers to members of the same array object are
+subtracted, the difference is divided by the size of a member. The
+result represents the difference of the subscripts of the two array
+members. The size of the result is implementation-defined, and its
+type (a signed integral type) is ptrdiff_t defined in the <stddef.h>
+header. As with any other arithmetic overflow, if the result does not
+fit in the space provided, the behavior is undefined. If two pointers
+that do not point to members of the same array object are subtracted,
+the behavior is undefined. However, if P points either to a member of
+an array object or one past the last member of an array object, and Q
+points to the last member of the same array object, the expression
+(Q+1) - P has the same value as (Q-P) + 1 , even though Q+1 does not
+point to a member of the array object.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ common definitions <stddef.h> (<A href="
+ #4.1.5">4.1.5</A>).
+</FONT></P><H4><A name="3.3.7">3.3.7 Bitwise shift operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="shift-expression">shift-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #additive-expression">additive-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #shift-expression">shift-expression</A></FONT> <FONT class="term"><<</FONT> <FONT class="nonterm"><A href="
+ #additive-expression">additive-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #shift-expression">shift-expression</A></FONT> <FONT class="term">>></FONT> <FONT class="nonterm"><A href="
+ #additive-expression">additive-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each of the operands shall have integral type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The integral promotions are performed on each of the operands. The
+type of the result is that of the promoted left operand. If the value
+of the right operand is negative or is greater than or equal to the
+width in bits of the promoted left operand, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated
+bits are filled with zeros. If E1 has an unsigned type, the value of
+the result is E1 multiplied by the quantity, 2 raised to the power E2,
+reduced modulo ULONG_MAX+1 if E1 has type unsigned long, UINT_MAX+1
+otherwise. (The constants ULONG_MAX and UINT_MAX are defined in the
+header <limits.h> .)
+</FONT></P><P>
+<FONT size="-1"> The result of E1 >> E2 is E1 right-shifted E2 bit positions. If E1
+has an unsigned type or if E1 has a signed type and a nonnegative
+value, the value of the result is the integral part of the quotient of
+E1 divided by the quantity, 2 raised to the power E2 . If E1 has a
+signed type and a negative value, the resulting value is
+implementation-defined.
+</FONT></P></P><H4><A name="3.3.8">3.3.8 Relational operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="relational-expression">relational-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #shift-expression">shift-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #relational-expression">relational-expression</A></FONT> <FONT class="term"><</FONT> <FONT class="nonterm"><A href="
+ #shift-expression">shift-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #relational-expression">relational-expression</A></FONT> <FONT class="term">></FONT> <FONT class="nonterm"><A href="
+ #shift-expression">shift-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #relational-expression">relational-expression</A></FONT> <FONT class="term"><=</FONT> <FONT class="nonterm"><A href="
+ #shift-expression">shift-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #relational-expression">relational-expression</A></FONT> <FONT class="term">>=</FONT> <FONT class="nonterm"><A href="
+ #shift-expression">shift-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> One of the following shall hold:
+</FONT></P><P>
+<FONT size="-1"> * both operands have arithmetic type;
+</FONT></P><P>
+<FONT size="-1"> * both operands are pointers to qualified or unqualified versions of
+ compatible object types; or
+</FONT></P><P>
+<FONT size="-1"> * both operands are pointers to qualified or unqualified versions of
+ compatible incomplete types.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> If both of the operands have arithmetic type, the usual arithmetic
+conversions are performed.
+</FONT></P><P>
+<FONT size="-1"> When two pointers are compared, the result depends on the relative
+locations in the address space of the objects pointed to. If the
+objects pointed to are members of the same aggregate object, pointers
+to structure members declared later compare higher than pointers to
+members declared earlier in the structure, and pointers to array
+elements with larger subscript values compare higher than pointers to
+elements of the same array with lower subscript values. All pointers
+to members of the same union object compare equal. If the objects
+pointed to are not members of the same aggregate or union object, the
+result is undefined, with the following exception. If P points to the
+last member of an array object and Q points to a member of the same
+array object, the pointer expression P+1 compares higher than Q , even
+though P+1 does not point to a member of the array object.
+</FONT></P><P>
+<FONT size="-1"> Each of the operators < (less than), > (greater than), <= (less
+than or equal to), and >= (greater than or equal to) shall yield 1 if
+the specified relation is true and 0 if it is false.<SUP><A href="
+ #38">38</A></SUP> The result
+has type int.
+</FONT></P></P><H4><A name="3.3.9">3.3.9 Equality operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="equality-expression">equality-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #relational-expression">relational-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #equality-expression">equality-expression</A></FONT> <FONT class="term">==</FONT> <FONT class="nonterm"><A href="
+ #relational-expression">relational-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #equality-expression">equality-expression</A></FONT> <FONT class="term">!=</FONT> <FONT class="nonterm"><A href="
+ #relational-expression">relational-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> One of the following shall hold:
+</FONT></P><P>
+<FONT size="-1"> * both operands have arithmetic type;
+</FONT></P><P>
+<FONT size="-1"> * both operands are pointers to qualified or unqualified versions of
+ compatible types;
+</FONT></P><P>
+<FONT size="-1"> * one operand is a pointer to an object or incomplete type and the
+ other is a qualified or unqualified version of void ; or
+</FONT></P><P>
+<FONT size="-1"> * one operand is a pointer and the other is a null pointer constant.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The == (equal to) and the != (not equal to) operators are analogous
+to the relational operators except for their lower precedence.<SUP><A href="
+ #39">39</A></SUP></FONT></P><P>
+<FONT size="-1"> If two pointers to object or incomplete types compare equal, they
+point to the same object. If two pointers to functions compare equal,
+they point to the same function. If two pointers point to the same
+object or function, they compare equal.<SUP><A href="
+ #40">40</A></SUP> If one of the operands is
+a pointer to an object or incomplete type and the other has type
+pointer to a qualified or unqualified version of void , the pointer to
+an object or incomplete type is converted to the type of the other
+operand.
+</FONT></P></P><H4><A name="3.3.10">3.3.10 Bitwise AND operator</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="AND-expression">AND-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #equality-expression">equality-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #AND-expression">AND-expression</A></FONT> <FONT class="term">&</FONT> <FONT class="nonterm"><A href="
+ #equality-expression">equality-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each of the operands shall have integral type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The usual arithmetic conversions are performed on the operands.
+</FONT></P><P>
+<FONT size="-1"> The result of the binary & operator is the bitwise AND of the
+operands (that is, each bit in the result is set if and only if each
+of the corresponding bits in the converted operands is set).
+</FONT></P></P><H4><A name="3.3.11">3.3.11 Bitwise exclusive OR operator</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="exclusive-OR-expression">exclusive-OR-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #AND-expression">AND-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #exclusive-OR-expression">exclusive-OR-expression</A></FONT> <FONT class="term">^</FONT> <FONT class="nonterm"><A href="
+ #AND-expression">AND-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each of the operands shall have integral type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The usual arithmetic conversions are performed on the operands.
+</FONT></P><P>
+<FONT size="-1"> The result of the ^ operator is the bitwise exclusive OR of the
+operands (that is, each bit in the result is set if and only if
+exactly one of the corresponding bits in the converted operands is
+set).
+</FONT></P></P><H4><A name="3.3.12">3.3.12 Bitwise inclusive OR operator</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="inclusive-OR-expression">inclusive-OR-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #exclusive-OR-expression">exclusive-OR-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #inclusive-OR-expression">inclusive-OR-expression</A></FONT> <FONT class="term">|</FONT> <FONT class="nonterm"><A href="
+ #exclusive-OR-expression">exclusive-OR-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each of the operands shall have integral type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The usual arithmetic conversions are performed on the operands.
+</FONT></P><P>
+<FONT size="-1"> The result of the | operator is the bitwise inclusive OR of the
+operands (that is, each bit in the result is set if and only if at
+least one of the corresponding bits in the converted operands is set).
+</FONT></P></P><H4><A name="3.3.13">3.3.13 Logical AND operator</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="logical-AND-expression">logical-AND-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #inclusive-OR-expression">inclusive-OR-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #logical-AND-expression">logical-AND-expression</A></FONT> <FONT class="term">&&</FONT> <FONT class="nonterm"><A href="
+ #inclusive-OR-expression">inclusive-OR-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each of the operands shall have scalar type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The && operator shall yield 1 if both of its operands compare
+unequal to 0, otherwise it yields 0. The result has type int.
+</FONT></P><P>
+<FONT size="-1"> Unlike the bitwise binary & operator, the && operator guarantees
+left-to-right evaluation; there is a sequence point after the
+evaluation of the first operand. If the first operand compares equal
+to 0, the second operand is not evaluated.
+</FONT></P></P><H4><A name="3.3.14">3.3.14 Logical OR operator</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="logical-OR-expression">logical-OR-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #logical-AND-expression">logical-AND-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #logical-OR-expression">logical-OR-expression</A></FONT> <FONT class="term">||</FONT> <FONT class="nonterm"><A href="
+ #logical-AND-expression">logical-AND-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each of the operands shall have scalar type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The || operator shall yield 1 if either of its operands compare
+unequal to 0, otherwise it yields 0. The result has type int.
+</FONT></P><P>
+<FONT size="-1"> Unlike the bitwise | operator, the || operator guarantees
+left-to-right evaluation; there is a sequence point after the
+evaluation of the first operand. If the first operand compares
+unequal to 0, the second operand is not evaluated.
+</FONT></P></P><H4><A name="3.3.15">3.3.15 Conditional operator</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="conditional-expression">conditional-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #logical-OR-expression">logical-OR-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #logical-OR-expression">logical-OR-expression</A></FONT> <FONT class="term">?</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> : <FONT class="nonterm"><A href="
+ #conditional-expression">conditional-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The first operand shall have scalar type.
+</FONT></P><P>
+<FONT size="-1"> One of the following shall hold for the second and third operands:
+</FONT></P><P>
+<FONT size="-1"> * both operands have arithmetic type;
+</FONT></P><P>
+<FONT size="-1"> * both operands have compatible structure or union types;
+</FONT></P><P>
+<FONT size="-1"> * both operands have void type;
+</FONT></P><P>
+<FONT size="-1"> * both operands are pointers to qualified or unqualified versions of
+ compatible types;
+</FONT></P><P>
+<FONT size="-1"> * one operand is a pointer and the other is a null pointer constant; or
+</FONT></P><P>
+<FONT size="-1"> * one operand is a pointer to an object or incomplete type and the
+ other is a pointer to a qualified or unqualified version of void .
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The first operand is evaluated; there is a sequence point after its
+evaluation. The second operand is evaluated only if the first
+compares unequal to 0; the third operand is evaluated only if the
+first compares equal to 0; the value of the second or third operand
+(whichever is evaluated) is the result.<SUP><A href="
+ #41">41</A></SUP></FONT></P><P>
+<FONT size="-1"> If both the second and third operands have arithmetic type, the
+usual arithmetic conversions are performed to bring them to a common
+type and the result has that type. If both the operands have
+structure or union type, the result has that type. If both operands
+have void type, the result has void type.
+</FONT></P><P>
+<FONT size="-1"> If both the second and third operands are pointers or one is a null
+pointer constant and the other is a pointer, the result type is a
+pointer to a type qualified with all the type qualifiers of the types
+pointed-to by both operands. Furthermore, if both operands are
+pointers to compatible types or differently qualified versions of a
+compatible type, the result has the composite type; if one operand is
+a null pointer constant, the result has the type of the other operand;
+otherwise, one operand is a pointer to void or a qualified version of
+void, in which case the other operand is converted to type pointer to
+void, and the result has that type.
+</FONT></P></P><H4><A name="3.3.16">3.3.16 Assignment operators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="assignment-expression">assignment-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #conditional-expression">conditional-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #unary-expression">unary-expression</A></FONT> <FONT class="nonterm"><A href="
+ #assignment-operator">assignment-operator</A></FONT> <FONT class="nonterm"><A href="
+ #assignment-expression">assignment-expression</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="assignment-operator">assignment-operator</A></FONT><FONT size="-1">: one of</FONT><BR>
+ <P class="nonterm-defseq">
+<FONT class="term">=</FONT> <FONT class="term">*=</FONT> <FONT class="term">/=</FONT> <FONT class="term">%=</FONT> <FONT class="term">+=</FONT> <FONT class="term">-=</FONT> <FONT class="term"><<=</FONT> <FONT class="term">>>=</FONT> <FONT class="term">&=</FONT> <FONT class="term">^=</FONT> <FONT class="term">|=</FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> An assignment operator shall have a modifiable lvalue as its left operand.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An assignment operator stores a value in the object designated by
+the left operand. An assignment expression has the value of the left
+operand after the assignment, but is not an lvalue. The type of an
+assignment expression is the type of the left operand unless the left
+operand has qualified type, in which case it is the unqualified
+version of the type of the left operand. The side effect of updating
+the stored value of the left operand shall occur between the previous
+and the next sequence point.
+</FONT></P><P>
+<FONT size="-1"> The order of evaluation of the operands is unspecified.
+</FONT></P></P>
+
+<H5><A name="3.3.16.1">3.3.16.1 Simple assignment</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> One of the following shall hold:<SUP><A href="
+ #42">42</A></SUP></FONT></P><P>
+<FONT size="-1"> * the left operand has qualified or unqualified arithmetic type and
+ the right has arithmetic type;
+</FONT></P><P>
+<FONT size="-1"> * the left operand has a qualified or unqualified version of a
+ structure or union type compatible with the type of the right;
+</FONT></P><P>
+<FONT size="-1"> * both operands are pointers to qualified or unqualified versions of
+ compatible types, and the type pointed to by the left has all the
+ qualifiers of the type pointed to by the right;
+</FONT></P><P>
+<FONT size="-1"> * one operand is a pointer to an object or incomplete type and the
+ other is a pointer to a qualified or unqualified version of void, and
+ the type pointed to by the left has all the qualifiers of the type
+ pointed to by the right; or
+</FONT></P><P>
+<FONT size="-1"> * the left operand is a pointer and the right is a null pointer constant.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> In simple assignment ( = ), the value of the right operand is
+ converted to the type of the assignment expression and replaces the
+ value stored in the object designated by the left operand.
+</FONT></P><P>
+<FONT size="-1"> If the value being stored in an object is accessed from another
+ object that overlaps in any way the storage of the first object, then
+ the overlap shall be exact and the two objects shall have qualified or
+ unqualified versions of a compatible type; otherwise the behavior is
+ undefined.
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> In the program fragment
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int f(void);
+ char c;
+ /*...*/
+ /*...*/ ((c = f()) == -1) /*...*/
+</FONT></P></PRE><P>
+<FONT size="-1">the int value returned by the function may be truncated when stored in
+the char, and then converted back to int width prior to the
+comparison. In an implementation in which ``plain'' char has the same
+range of values as unsigned char (and char is narrower than int ), the
+result of the conversion cannot be negative, so the operands of the
+comparison can never compare equal. Therefore, for full portability
+the variable c should be declared as int.
+</FONT></P></P><H5><A name="3.3.16.2">3.3.16.2 Compound assignment</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> For the operators += and -= only, either the left operand shall be
+a pointer to an object type and the right shall have integral type, or
+the left operand shall have qualified or unqualified arithmetic type
+and the right shall have arithmetic type.
+</FONT></P><P>
+<FONT size="-1"> For the other operators, each operand shall have arithmetic type
+consistent with those allowed by the corresponding binary operator.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A compound assignment of the form E1 op = E2 differs from the
+simple assignment expression E1 = E1 op (E2) only in that the lvalue
+E1 is evaluated only once.
+</FONT></P></P><H4><A name="3.3.17">3.3.17 Comma operator</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="expression">expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #assignment-expression">assignment-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> <FONT class="term">,</FONT> <FONT class="nonterm"><A href="
+ #assignment-expression">assignment-expression</A></FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The left operand of a comma operator is evaluated as a void
+expression; there is a sequence point after its evaluation. Then the
+right operand is evaluated; the result has its type and value.<SUP><A href="
+ #43">43</A></SUP></FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> As indicated by the syntax, in contexts where a comma is a
+punctuator (in lists of arguments to functions and lists of
+initializers) the comma operator as described in this section cannot
+appear. On the other hand, it can be used within a parenthesized
+expression or within the second expression of a conditional operator
+in such contexts. In the function call
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> f(a, (t=3, t+2), c)
+</FONT></P></PRE><P>
+<FONT size="-1">the function has three arguments, the second of which has the value 5.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ initialization (<A href="
+ #3.5.7">3.5.7</A>).
+</FONT></P><H3><A name="3.4">3.4 CONSTANT EXPRESSIONS</A></H3>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="constant-expression">constant-expression</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #conditional-expression">conditional-expression</A></FONT></P></P></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> A constant expression can be evaluated during translation rather
+than runtime, and accordingly may be used in any place that a constant
+may be.
+</FONT></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Constant expressions shall not contain assignment, increment,
+decrement, function-call, or comma operators, except when they are
+contained within the operand of a sizeof operator.<SUP><A href="
+ #44">44</A></SUP></FONT></P><P>
+<FONT size="-1"> Each constant expression shall evaluate to a constant that is in
+the range of representable values for its type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An expression that evaluates to a constant is required in several
+contexts.<SUP><A href="
+ #45">45</A></SUP> If the expression is evaluated in the translation
+environment, the arithmetic precision and range shall be at least as
+great as if the expression were being evaluated in the execution
+environment.
+</FONT></P><P>
+<FONT size="-1"> An integral constant expression shall have integral type and shall
+only have operands that are integer constants, enumeration constants,
+character constants, sizeof expressions, and floating constants that
+are the immediate operands of casts. Cast operators in an integral
+constant expression shall only convert arithmetic types to integral
+types, except as part of an operand to the sizeof operator.
+</FONT></P><P>
+<FONT size="-1"> More latitude is permitted for constant expressions in
+initializers. Such a constant expression shall evaluate to one of the
+following:
+</FONT></P><P>
+<FONT size="-1"> * an arithmetic constant expression,
+</FONT></P><P>
+<FONT size="-1"> * an address constant, or
+</FONT></P><P>
+<FONT size="-1"> * an address constant for an object type plus or minus an integral
+ constant expression.
+</FONT></P><P>
+<FONT size="-1"> An arithmetic constant expression shall have arithmetic type and
+shall only have operands that are integer constants, floating
+constants, enumeration constants, character constants, and sizeof
+expressions. Cast operators in an arithmetic constant expression
+shall only convert arithmetic types to arithmetic types, except as
+part of an operand to the sizeof operator.
+</FONT></P><P>
+<FONT size="-1"> An address constant is a pointer to an lvalue designating an object
+of static storage duration, or to a function designator; it shall be
+created explicitly, using the unary & operator, or implicitly, by the
+use of an expression of array or function type. The array-subscript
+[] and member-access . and -> operators, the address & and
+indirection * unary operators, and pointer casts may be used in the
+creation an address constant, but the value of an object shall not be
+accessed by use of these operators.
+</FONT></P><P>
+<FONT size="-1"> The semantic rules for the evaluation of a constant expression are
+the same as for non-constant expressions.<SUP><A href="
+ #46">46</A></SUP></FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ initialization (<A href="
+ #3.5.7">3.5.7</A>).
+</FONT></P><H3><A name="3.5">3.5 DECLARATIONS</A></H3>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="declaration">declaration</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declaration-specifiers">declaration-specifiers</A></FONT> <FONT class="nonterm"><A href="
+ #init-declarator-list">init-declarator-list</A><SUB>opt</SUB></FONT> <FONT class="term">;</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="declaration-specifiers">declaration-specifiers</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #storage-class-specifier">storage-class-specifier</A></FONT> <FONT class="nonterm"><A href="
+ #declaration-specifiers">declaration-specifiers</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #type-specifier">type-specifier</A></FONT> <FONT class="nonterm"><A href="
+ #declaration-specifiers">declaration-specifiers</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #type-qualifier">type-qualifier</A></FONT> <FONT class="nonterm"><A href="
+ #declaration-specifiers">declaration-specifiers</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="init-declarator-list">init-declarator-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #init-declarator">init-declarator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #init-declarator-list">init-declarator-list</A></FONT> <FONT class="term">,</FONT> <FONT class="nonterm"><A href="
+ #init-declarator">init-declarator</A></FONT> </P></P><P class="syntax-def"> <FONT class="nonterm"><A name="init-declarator">init-declarator</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declarator">declarator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declarator">declarator</A></FONT> <FONT class="term">=</FONT> <FONT class="nonterm"><A href="
+ #initializer">initializer</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A declaration shall declare at least a declarator, a tag, or the
+members of an enumeration.
+</FONT></P><P>
+<FONT size="-1"> If an identifier has no linkage, there shall be no more than one
+declaration of the identifier (in a declarator or type specifier) with
+the same scope and in the same name space, except for tags as
+specified in <A href="
+ #3.5.2.3">3.5.2.3</A></FONT></P><P>
+<FONT size="-1"> All declarations in the same scope that refer to the same object or
+function shall specify compatible types.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A declaration specifies the interpretation and attributes of a set
+of identifiers. A declaration that also causes storage to be reserved
+for an object or function named by an identifier is a definition .<SUP><A href="
+ #47">47</A></SUP></FONT></P><P>
+<FONT size="-1"> The declaration specifiers consist of a sequence of specifiers that
+indicate the linkage, storage duration, and part of the type of the
+entities that the declarators denote. The init-declarator-list is a
+comma-separated sequence of declarators, each of which may have
+additional type information, or an initializer, or both. The
+declarators contain the identifiers (if any) being declared.
+</FONT></P><P>
+<FONT size="-1"> If an identifier for an object is declared with no linkage, the
+type for the object shall be complete by the end of its declarator, or
+by the end of its init-declarator if it has an initializer.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ declarators (<A href="
+ #3.5.4">3.5.4</A>), enumeration specifiers
+(<A href="
+ #3.5.2.2">3.5.2.2</A>), initialization (<A href="
+ #3.5.7">3.5.7</A>), tags (<A href="
+ #3.5.2.3">3.5.2.3</A>).
+</FONT></P><H4><A name="3.5.1">3.5.1 Storage-class specifiers</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="storage-class-specifier">storage-class-specifier</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">typedef</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">extern</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">static</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">auto</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">register</FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> At most one storage-class specifier may be given in the declaration
+specifiers in a declaration.<SUP><A href="
+ #48">48</A></SUP></FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The typedef specifier is called a ``storage-class specifier'' for
+syntactic convenience only; it is discussed in <A href="
+ #3.5.6">3.5.6</A> The meanings
+of the various linkages and storage durations were discussed in
+<A href="
+ #3.1.2.2">3.1.2.2</A> and <A href="
+ #3.1.2.4">3.1.2.4</A></FONT></P><P>
+<FONT size="-1"> A declaration of an identifier for an object with storage-class
+specifier register suggests that access to the object be as fast as
+possible. The extent to which such suggestions are effective is
+implementation-defined.<SUP><A href="
+ #49">49</A></SUP></FONT></P><P>
+<FONT size="-1"> The declaration of an identifier for a function that has block
+scope shall have no explicit storage-class specifier other than extern.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ type definitions (<A href="
+ #3.5.6">3.5.6</A>).
+</FONT></P><H4><A name="3.5.2">3.5.2 Type specifiers</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="type-specifier">type-specifier</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">void</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">char</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">short</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">int</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">long</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">float</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">double</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">signed</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">unsigned</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #struct-or-union-specifier">struct-or-union-specifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #enum-specifier">enum-specifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #typedef-name">typedef-name</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1">Each list of type specifiers shall be one of the following sets; the
+type specifiers may occur in any order, possibly intermixed with the
+other declaration specifiers.
+</FONT></P><P>
+<FONT size="-1"> * void
+</FONT></P><P>
+<FONT size="-1"> * char
+</FONT></P><P>
+<FONT size="-1"> * signed char
+</FONT></P><P>
+<FONT size="-1"> * unsigned char
+</FONT></P><P>
+<FONT size="-1"> * short , signed short , short int , or signed short int
+</FONT></P><P>
+<FONT size="-1"> * unsigned short , or unsigned short int
+</FONT></P><P>
+<FONT size="-1"> * int , signed , signed int , or no type specifiers
+</FONT></P><P>
+<FONT size="-1"> * unsigned , or unsigned int
+</FONT></P><P>
+<FONT size="-1"> * long , signed long , long int , or signed long int
+</FONT></P><P>
+<FONT size="-1"> * unsigned long , or unsigned long int
+</FONT></P><P>
+<FONT size="-1"> * float
+</FONT></P><P>
+<FONT size="-1"> * double
+</FONT></P><P>
+<FONT size="-1"> * long double
+</FONT></P><P>
+<FONT size="-1"> * struct-or-union specifier
+</FONT></P><P>
+<FONT size="-1"> * enum-specifier
+</FONT></P><P>
+<FONT size="-1"> * typedef-name
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> Specifiers for structures, unions, and enumerations are discussed
+in <A href="
+ #3.5.2.1">3.5.2.1</A> through <A href="
+ #3.5.2.3">3.5.2.3</A> Declarations of typedef names are
+discussed in <A href="
+ #3.5.6">3.5.6</A> The characteristics of the other types are
+discussed in <A href="
+ #3.1.2.5">3.1.2.5</A></FONT></P><P>
+<FONT size="-1"> Each of the above comma-separated lists designates the same type,
+except that for bit-field declarations, signed int (or signed ) may
+differ from int (or no type specifiers).
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ enumeration specifiers (<A href="
+ #3.5.2.2">3.5.2.2</A>), structure and
+union specifiers (<A href="
+ #3.5.2.1">3.5.2.1</A>), tags (<A href="
+ #3.5.2.3">3.5.2.3</A>), type definitions (<A href="
+ #3.5.6">3.5.6</A>).
+</FONT></P><H5><A name="3.5.2.1">3.5.2.1 Structure and union specifiers</A></H5>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="struct-or-union-specifier">struct-or-union-specifier</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #struct-or-union">struct-or-union</A></FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A><SUB>opt</SUB></FONT> <FONT class="term">{</FONT> <FONT class="nonterm"><A href="
+ #struct-declaration-list">struct-declaration-list</A></FONT> <FONT class="term">}</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #struct-or-union">struct-or-union</A></FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="struct-or-union">struct-or-union</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">struct</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">union</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="struct-declaration-list">struct-declaration-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #struct-declaration">struct-declaration</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #struct-declaration-list">struct-declaration-list</A></FONT> <FONT class="nonterm"><A href="
+ #struct-declaration">struct-declaration</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="struct-declaration">struct-declaration</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #specifier-qualifier-list">specifier-qualifier-list</A></FONT> <FONT class="nonterm"><A href="
+ #struct-declarator-list">struct-declarator-list</A></FONT> <FONT class="term">;</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="specifier-qualifier-list">specifier-qualifier-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #type-specifier">type-specifier</A></FONT> <FONT class="nonterm"><A href="
+ #specifier-qualifier-list">specifier-qualifier-list</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #type-qualifier">type-qualifier</A></FONT> <FONT class="nonterm"><A href="
+ #specifier-qualifier-list">specifier-qualifier-list</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="struct-declarator-list">struct-declarator-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #struct-declarator">struct-declarator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #struct-declarator-list">struct-declarator-list</A></FONT> <FONT class="term">,</FONT> <FONT class="nonterm"><A href="
+ #struct-declarator">struct-declarator</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="struct-declarator">struct-declarator</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declarator">declarator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declarator">declarator</A><SUB>opt</SUB></FONT> : <FONT class="nonterm"><A href="
+ #constant-expression">constant-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A structure or union shall not contain a member with incomplete or
+function type. Hence it shall not contain an instance of itself (but
+may contain a pointer to an instance of itself).
+</FONT></P><P>
+<FONT size="-1"> The expression that specifies the width of a bit-field shall be an
+integral constant expression that has nonnegative value that shall not
+exceed the number of bits in an ordinary object of compatible type.
+If the value is zero, the declaration shall have no declarator.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> As discussed in <A href="
+ #3.1.2.5">3.1.2.5</A>, a structure is a type consisting of a
+sequence of named members, whose storage is allocated in an ordered
+sequence, and a union is a type consisting of a sequence of named
+members, whose storage overlap.
+</FONT></P><P>
+<FONT size="-1"> Structure and union specifiers have the same form.
+</FONT></P><P>
+<FONT size="-1"> The presence of a struct-declaration-list in a
+struct-or-union-specifier declares a new type, within a translation
+unit. The struct-declaration-list is a sequence of declarations for
+the members of the structure or union. The type is incomplete until
+after the } that terminates the list.
+</FONT></P><P>
+<FONT size="-1"> A member of a structure or union may have any object type. In
+addition, a member may be declared to consist of a specified number of
+bits (including a sign bit, if any). Such a member is called a
+bit-field ;<SUP><A href="
+ #50">50</A></SUP> its width is preceded by a colon.
+</FONT></P><P>
+<FONT size="-1"> A bit-field may have type int , unsigned int , or signed int .
+Whether the high-order bit position of a ``plain'' int bit-field is
+treated as a sign bit is implementation-defined. A bit-field is
+interpreted as an integral type consisting of the specified number of
+bits.
+</FONT></P><P>
+<FONT size="-1"> An implementation may allocate any addressable storage unit large
+enough to hold a bit-field. If enough space remains, a bit-field that
+immediately follows another bit-field in a structure shall be packed
+into adjacent bits of the same unit. If insufficient space remains,
+whether a bit-field that does not fit is put into the next unit or
+overlaps adjacent units is implementation-defined. The order of
+allocation of bit-fields within a unit (high-order to low-order or
+low-order to high-order) is implementation-defined. The alignment of
+the addressable storage unit is unspecified.
+</FONT></P><P>
+<FONT size="-1"> A bit-field declaration with no declarator, but only a colon and a
+width, indicates an unnamed bit-field.<SUP><A href="
+ #51">51</A></SUP> As a special case of this,
+a bit-field with a width of 0 indicates that no further bit-field is
+to be packed into the unit in which the previous bit-field, if any,
+was placed.
+</FONT></P><P>
+<FONT size="-1"> Each non-bit-field member of a structure or union object is aligned
+in an implementation-defined manner appropriate to its type.
+</FONT></P><P>
+<FONT size="-1"> Within a structure object, the non-bit-field members and the units
+in which bit-fields reside have addresses that increase in the order
+in which they are declared. A pointer to a structure object, suitably
+cast, points to its initial member (or if that member is a bit-field,
+then to the unit in which it resides), and vice versa. There may
+therefore be unnamed holes within a structure object, but not at its
+beginning, as necessary to achieve the appropriate alignment.
+</FONT></P><P>
+<FONT size="-1"> The size of a union is sufficient to contain the largest of its
+members. The value of at most one of the members can be stored in a
+union object at any time. A pointer to a union object, suitably cast,
+points to each of its members (or if a member is a bit-field, then to
+the unit in which it resides), and vice versa.
+</FONT></P><P>
+<FONT size="-1"> There may also be unnamed padding at the end of a structure or
+union, as necessary to achieve the appropriate alignment were the
+structure or union to be a member of an array.
+</FONT></P></P><H5><A name="3.5.2.2">3.5.2.2 Enumeration specifiers</A></H5>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="enum-specifier">enum-specifier</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">enum</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A><SUB>opt</SUB></FONT> <FONT class="term">{</FONT> <FONT class="nonterm"><A href="
+ #enumerator-list">enumerator-list</A></FONT> <FONT class="term">}</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">enum</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="enumerator-list">enumerator-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #enumerator">enumerator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #enumerator-list">enumerator-list</A></FONT> <FONT class="term">,</FONT> <FONT class="nonterm"><A href="
+ #enumerator">enumerator</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="enumerator">enumerator</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #enumeration-constant">enumeration-constant</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #enumeration-constant">enumeration-constant</A></FONT> <FONT class="term">=</FONT> <FONT class="nonterm"><A href="
+ #constant-expression">constant-expression</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The expression that defines the value of an enumeration constant
+shall be an integral constant expression that has a value
+representable as an int.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The identifiers in an enumerator list are declared as constants
+that have type int and may appear wherever such are permitted.<SUP><A href="
+ #52">52</A></SUP> An
+enumerator with = defines its enumeration constant as the value of the
+constant expression. If the first enumerator has no = , the value of
+its enumeration constant is 0. Each subsequent enumerator with no =
+defines its enumeration constant as the value of the constant
+expression obtained by adding 1 to the value of the previous
+enumeration constant. (A combination of both forms of enumerators may
+produce enumeration constants with values that duplicate other values
+in the same enumeration.) The enumerators of an enumeration are also
+known as its members.
+</FONT></P><P>
+<FONT size="-1"> Each enumerated type shall be compatible with an integer type; the
+choice of type is implementation-defined.
+</FONT></P></P><H6>Example</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> enum hue { chartreuse, burgundy, claret=20, winedark };
+ /*...*/
+ enum hue col, *cp;
+ /*...*/
+ col = claret;
+ cp = &col;
+ /*...*/
+ /*...*/ (*cp != burgundy) /*...*/
+</FONT></P></PRE><P>
+<FONT size="-1">makes hue the tag of an enumeration, and then declares col as an
+object that has that type and cp as a pointer to an object that has
+that type. The enumerated values are in the set {0, 1, 20, 21}.
+</FONT></P></P><H5><A name="3.5.2.3">3.5.2.3 Tags</A></H5>
+<P>
+<FONT size="-1"> A type specifier of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct-or-union identifier { struct-declaration-list }
+ enum identifier { enumerator-list }
+</FONT></P></PRE><P>
+<FONT size="-1">declares the identifier to be the tag of the structure, union, or
+enumeration specified by the list. The list defines the structure
+content ,union content ,or enumeration content .If this declaration of
+the tag is visible, a subsequent declaration that uses the tag and
+that omits the bracketed list specifies the declared structure, union,
+or enumerated type. Subsequent declarations in the same scope shall
+omit the bracketed list.
+</FONT></P><P>
+<FONT size="-1"> If a type specifier of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct-or-union identifier
+</FONT></P></PRE><P>
+<FONT size="-1">occurs prior to the declaration that defines the content, the
+structure or union is an incomplete type.<SUP><A href="
+ #53">53</A></SUP> It declares a tag that
+specifies a type that may be used only when the size of an object of
+the specified type is not needed.<SUP><A href="
+ #54">54</A></SUP> If the type is to be completed,
+another declaration of the tag in the same scope (but not in an
+enclosed block, which declares a new type known only within that
+block) shall define the content. A declaration of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct-or-union identifier ;
+</FONT></P></PRE><P>
+<FONT size="-1">specifies a structure or union type and declares a tag, both visible
+only within the scope in which the declaration occurs. It specifies a
+new type distinct from any type with the same tag in an enclosing
+scope (if any).
+</FONT></P><P>
+<FONT size="-1"> A type specifier of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct-or-union { struct-declaration-list }
+ enum { enumerator-list }
+</FONT></P></PRE><P>
+<FONT size="-1">specifies a new structure, union, or enumerated type, within the
+translation unit, that can only be referred to by the declaration of
+which it is a part.<SUP><A href="
+ #55">55</A></SUP></FONT></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> This mechanism allows declaration of a self-referential structure.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct tnode {
+ int count;
+ struct tnode *left, *right;
+ };
+</FONT></P></PRE><P>
+<FONT size="-1">specifies a structure that contains an integer and two pointers to
+objects of the same type. Once this declaration has been given, the
+declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct tnode s, *sp;
+</FONT></P></PRE><P>
+<FONT size="-1">declares s to be an object of the given type and sp to be a pointer to
+an object of the given type. With these declarations, the expression
+sp->left refers to the left struct tnode pointer of the object to
+which sp points; the expression s.right->count designates the count
+member of the right struct tnode pointed to from s .
+</FONT></P><P>
+<FONT size="-1"> The following alternative formulation uses the typedef mechanism:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> typedef struct tnode TNODE;
+ struct tnode {
+ int count;
+ TNODE *left, *right;
+ };
+ TNODE s, *sp;
+</FONT></P></PRE><P>
+<FONT size="-1"> To illustrate the use of prior declaration of a tag to specify a
+pair of mutually-referential structures, the declarations
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct s1 { struct s2 *s2p; /*...*/ }; /* D1 */
+ struct s2 { struct s1 *s1p; /*...*/ }; /* D2 */
+</FONT></P></PRE><P>
+<FONT size="-1">specify a pair of structures that contain pointers to each other.
+Note, however, that if s2 were already declared as a tag in an
+enclosing scope, the declaration D1 would refer to it, not to the tag
+s2 declared in D2 . To eliminate this context sensitivity, the
+otherwise vacuous declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct s2;
+</FONT></P></PRE><P>
+<FONT size="-1">may be inserted ahead of D1. This declares a new tag s2 in the inner
+scope; the declaration D2 then completes the specification of the new type.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ type definitions (<A href="
+ #3.5.6">3.5.6</A>).
+</FONT></P>
+
+<H4><A name="3.5.3">3.5.3 Type qualifiers</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="type-qualifier">type-qualifier</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">const</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">volatile</FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The same type qualifier shall not appear more than once in the same
+specifier list or qualifier list, either directly or via one or more
+typedef s.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The properties associated with qualified types are meaningful only
+for expressions that are lvalues.<SUP><A href="
+ #56">56</A></SUP></FONT></P><P>
+<FONT size="-1"> If an attempt is made to modify an object defined with a
+const-qualified type through use of an lvalue with non-const-qualified
+type, the behavior is undefined. If an attempt is made to refer to an
+object defined with a volatile-qualified type through use of an lvalue
+with non-volatile-qualified type, the behavior is undefined.<SUP><A href="
+ #57">57</A></SUP></FONT></P><P>
+<FONT size="-1"> An object that has volatile-qualified type may be modified in ways
+unknown to the implementation or have other unknown side effects.
+Therefore any expression referring to such an object shall be
+evaluated strictly according to the rules of the abstract machine, as
+described in <A href="
+ #2.1.2.3">2.1.2.3</A> Furthermore, at every sequence point the value
+last stored in the object shall agree with that prescribed by the
+abstract machine, except as modified by the unknown factors mentioned
+previously.<SUP><A href="
+ #58">58</A></SUP> What constitutes an access to an object that has
+volatile-qualified type is implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> If the specification of an array type includes any type qualifiers,
+the element type is so-qualified, not the array type. If the
+specification of a function type includes any type qualifiers, the
+behavior is undefined.<SUP><A href="
+ #59">59</A></SUP></FONT></P><P>
+<FONT size="-1"> For two qualified types to be compatible, both shall have the
+identically qualified version of a compatible type; the order of type
+qualifiers within a list of specifiers or qualifiers does not affect
+the specified type.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> An object declared
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> extern const volatile int real_time_clock;
+</FONT></P></PRE><P>
+<FONT size="-1">may be modifiable by hardware, but cannot be assigned to, incremented,
+or decremented.
+</FONT></P><P>
+<FONT size="-1"> The following declarations and expressions illustrate the behavior
+when type qualifiers modify an aggregate type:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> const struct s { int mem; } cs = { 1 };
+ struct s ncs; /* the object ncs is modifiable */
+ typedef int A[2][3];
+ const A a = {{4, 5, 6}, {7, 8, 9}}; /* array of array of const int */
+ int *pi;
+ const int *pci;
+
+ ncs = cs; /* valid */
+ cs = ncs; /* violates modifiable lvalue constraint for = */
+ pi = &ncs.mem; /* valid */
+ pi = &cs.mem; /* violates type constraints for = */
+ pci = &cs.mem; /* valid */
+ pi = a[0]; /* invalid: a[0] has type ``const int * '' */
+</FONT></P></PRE></P><H4><A name="3.5.4">3.5.4 Declarators</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="declarator">declarator</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pointer">pointer</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #direct-declarator">direct-declarator</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="direct-declarator">direct-declarator</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #declarator">declarator</A></FONT> <FONT class="term">)</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #direct-declarator">direct-declarator</A></FONT> <FONT class="term">[</FONT> <FONT class="nonterm"><A href="
+ #constant-expression">constant-expression</A><SUB>opt</SUB></FONT> <FONT class="term">]</FONT> </P></P><P class="syntax-def"> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #direct-declarator">direct-declarator</A></FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #parameter-type-list">parameter-type-list</A></FONT> <FONT class="term">)</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #direct-declarator">direct-declarator</A></FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #identifier-list">identifier-list</A><SUB>opt</SUB></FONT> <FONT class="term">)</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="pointer">pointer</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">*</FONT> <FONT class="nonterm"><A href="
+ #type-qualifier-list">type-qualifier-list</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">*</FONT> <FONT class="nonterm"><A href="
+ #type-qualifier-list">type-qualifier-list</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #pointer">pointer</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="type-qualifier-list">type-qualifier-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #type-qualifier">type-qualifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #type-qualifier-list">type-qualifier-list</A></FONT> <FONT class="nonterm"><A href="
+ #type-qualifier">type-qualifier</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="parameter-type-list">parameter-type-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #parameter-list">parameter-list</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #parameter-list">parameter-list</A></FONT> <FONT class="term">,</FONT> <FONT class="term">...</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="parameter-list">parameter-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #parameter-declaration">parameter-declaration</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #parameter-list">parameter-list</A></FONT> <FONT class="term">,</FONT> <FONT class="nonterm"><A href="
+ #parameter-declaration">parameter-declaration</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="parameter-declaration">parameter-declaration</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declaration-specifiers">declaration-specifiers</A></FONT> <FONT class="nonterm"><A href="
+ #declarator">declarator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declaration-specifiers">declaration-specifiers</A></FONT> <FONT class="nonterm"><A href="
+ #abstract-declarator">abstract-declarator</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="identifier-list">identifier-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier-list">identifier-list</A></FONT> <FONT class="term">,</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> Each declarator declares one identifier, and asserts that when an
+operand of the same form as the declarator appears in an expression,
+it designates a function or object with the scope, storage duration,
+and type indicated by the declaration specifiers.
+</FONT></P><P>
+<FONT size="-1"> In the following subsections, consider a declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> T D1
+</FONT></P></PRE><P>
+<FONT size="-1">where T contains the declaration specifiers that specify a type T
+(such as int) and D1 is a declarator that contains an identifier
+ident . The type specified for the identifier ident in the various
+forms of declarator is described inductively using this notation.
+</FONT></P><P>
+<FONT size="-1"> If, in the declaration `` T D1 ,'' D1 has the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> identifier
+</FONT></P></PRE><P>
+<FONT size="-1">then the type specified for ident is T .
+</FONT></P><P>
+<FONT size="-1"> If, in the declaration `` T D1 ,'' D1 has the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> ( D )
+</FONT></P></PRE><P>
+<FONT size="-1">then ident has the type specified by the declaration `` T D .'' Thus,
+a declarator in parentheses is identical to the unparenthesized
+declarator, but the binding of complex declarators may be altered by
+parentheses.
+</FONT></P><P>
+<FONT size="-1">"Implementation limits"
+</FONT></P><P>
+<FONT size="-1"> The implementation shall allow the specification of types that have
+at least 12 pointer, array, and function declarators (in any valid
+combinations) modifying an arithmetic, a structure, a union, or an
+incomplete type, either directly or via one or more typedef s.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ type definitions (<A href="
+ #3.5.6">3.5.6</A>).
+</FONT></P><H5><A name="3.5.4.1">3.5.4.1 Pointer declarators</A></H5>
+<H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> If, in the declaration `` T D1 ,'' D1 has the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> * type-qualifier-list<opt> D
+</FONT></P></PRE><P>
+<FONT size="-1">and the type specified for ident in the declaration `` T D '' is ``
+"derived-declarator-type-list T" ,'' then the type specified for ident
+is `` "derived-declarator-type-list type-qualifier-list" pointer to T.''
+For each type qualifier in the list, ident is a so-qualified pointer.
+</FONT></P><P>
+<FONT size="-1"> For two pointer types to be compatible, both shall be identically
+qualified and both shall be pointers to compatible types.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The following pair of declarations demonstrates the difference
+between a ``variable pointer to a constant value'' and a ``constant
+pointer to a variable value.''
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> const int *ptr_to_constant;
+ int *const constant_ptr;
+</FONT></P></PRE><P>
+<FONT size="-1">The contents of the const int pointed to by ptr_to_constant shall not
+be modified, but ptr_to_constant itself may be changed to point to
+another const int . Similarly, the contents of the int pointed to by
+constant_ptr may be modified, but constant_ptr itself shall always
+point to the same location.
+</FONT></P><P>
+<FONT size="-1"> The declaration of the constant pointer constant_ptr may be
+clarified by including a definition for the type ``pointer to int .''
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> typedef int *int_ptr;
+ const int_ptr constant_ptr;
+</FONT></P></PRE><P>
+<FONT size="-1">declares constant_ptr as an object that has type ``const-qualified
+pointer to int .''
+</FONT></P></P><H5><A name="3.5.4.2">3.5.4.2 Array declarators</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The expression that specifies the size of an array shall be an
+integral constant expression that has a value greater than zero.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> If, in the declaration `` T D1 ,'' D1 has the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> D[ constant-expression<opt>]
+</FONT></P></PRE><P>
+<FONT size="-1">and the type specified for ident in the declaration `` T D '' is ``
+"derived-declarator-type-list T" ,'' then the type specified for ident
+is `` derived-declarator-type-list array of T .''<SUP><A href="
+ #60">60</A></SUP> If the size is
+not present, the array type is an incomplete type.
+</FONT></P><P>
+<FONT size="-1"> For two array types to be compatible, both shall have compatible
+element types, and if both size specifiers are present, they shall
+have the same value.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> float fa[11], *afp[17];
+</FONT></P></PRE><P>
+<FONT size="-1">declares an array of float numbers and an array of pointers to float
+numbers.
+</FONT></P><P>
+<FONT size="-1"> Note the distinction between the declarations
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> extern int *x;
+ extern int y[];
+</FONT></P></PRE><P>
+<FONT size="-1">The first declares x to be a pointer to int ; the second declares y to
+be an array of int of unspecified size (an incomplete type), the
+storage for which is defined elsewhere.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ function definitions (<A href="
+ #3.7.1">3.7.1</A>), initialization (<A href="
+ #3.5.7">3.5.7</A>).
+</FONT></P><H5><A name="3.5.4.3">3.5.4.3 Function declarators (including prototypes)</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A function declarator shall not specify a return type that is a
+function type or an array type.
+</FONT></P><P>
+<FONT size="-1"> The only storage-class specifier that shall occur in a parameter
+declaration is register.
+</FONT></P><P>
+<FONT size="-1"> An identifier list in a function declarator that is not part of a
+function definition shall be empty.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> If, in the declaration `` T D1 ,'' D1 has the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> D( parameter-type-list)
+ D( identifier-list<opt>)
+</FONT></P></PRE><P>
+<FONT size="-1">and the type specified for ident in the declaration `` T D '' is ``
+"derived-declarator-type-list T" ,'' then the type specified for ident
+is `` derived-declarator-type-list function returning T .''
+</FONT></P><P>
+<FONT size="-1"> A parameter type list specifies the types of, and may declare
+identifiers for, the parameters of the function. If the list
+terminates with an ellipsis ( , ... ), no information about the number
+or types of the parameters after the comma is supplied.<SUP><A href="
+ #61">61</A></SUP> The
+special case of void as the only item in the list specifies that the
+function has no parameters.
+</FONT></P><P>
+<FONT size="-1"> In a parameter declaration, a single typedef name in parentheses is
+taken to be an abstract declarator that specifies a function with a
+single parameter, not as redundant parentheses around the identifier
+for a declarator.
+</FONT></P><P>
+<FONT size="-1"> The storage-class specifier in the declaration specifiers for a
+parameter declaration, if present, is ignored unless the declared
+parameter is one of the members of the parameter type list for a
+function definition.
+</FONT></P><P>
+<FONT size="-1"> An identifier list declares only the identifiers of the parameters
+of the function. An empty list in a function declarator that is part
+of a function definition specifies that the function has no
+parameters. The empty list in a function declarator that is not part
+of a function definition specifies that no information about the
+number or types of the parameters is supplied.<SUP><A href="
+ #62">62</A></SUP></FONT></P><P>
+<FONT size="-1"> For two function types to be compatible, both shall specify
+compatible return types.<SUP><A href="
+ #63">63</A></SUP> Moreover, the parameter type lists, if
+both are present, shall agree in the number of parameters and in use
+of the ellipsis terminator; corresponding parameters shall have
+compatible types. If one type has a parameter type list and the other
+type is specified by a function declarator that is not part of a
+function definition and that contains an empty identifier list, the
+parameter list shall not have an ellipsis terminator and the type of
+each parameter shall be compatible with the type that results from the
+application of the default argument promotions. If one type has a
+parameter type list and the other type is specified by a function
+definition that contains a (possibly empty) identifier list, both
+shall agree in the number of parameters, and the type of each
+prototype parameter shall be compatible with the type that results
+from the application of the default argument promotions to the type of
+the corresponding identifier. (For each parameter declared with
+function or array type, its type for these comparisons is the one that
+results from conversion to a pointer type, as in <A href="
+ #3.7.1">3.7.1</A> For each
+parameter declared with qualified type, its type for these comparisons
+is the unqualified version of its declared type.)
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int f(void), *fip(), (*pfi)();
+</FONT></P></PRE><P>
+<FONT size="-1">declares a function f with no parameters returning an int , a function
+fip with no parameter specification returning a pointer to an int ,
+and a pointer pfi to a function with no parameter specification
+returning an int . It is especially useful to compare the last two.
+The binding of *fip() is *(fip()) , so that the declaration suggests,
+and the same construction in an expression requires, the calling of a
+function fip , and then using indirection through the pointer result
+to yield an int . In the declarator (*pfi)() , the extra parentheses
+are necessary to indicate that indirection through a pointer to a
+function yields a function designator, which is then used to call the
+function; it returns an int.
+</FONT></P><P>
+<FONT size="-1"> If the declaration occurs outside of any function, the identifiers
+have file scope and external linkage. If the declaration occurs
+inside a function, the identifiers of the functions f and fip have
+block scope and external linkage, and the identifier of the pointer
+pfi has block scope and no linkage.
+</FONT></P><P>
+<FONT size="-1"> Here are two more intricate examples.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int (*apfi[3])(int *x, int *y);
+</FONT></P></PRE><P>
+<FONT size="-1">declares an array apfi of three pointers to functions returning int .
+Each of these functions has two parameters that are pointers to int .
+The identifiers x and y are declared for descriptive purposes only and
+go out of scope at the end of the declaration of apfi . The
+declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int (*fpfi(int (*)(long), int))(int, ...);
+</FONT></P></PRE><P>
+<FONT size="-1">declares a function fpfi that returns a pointer to a function
+returning an int. The function fpfi has two parameters: a pointer to
+a function returning an int (with one parameter of type long ), and an
+int . The pointer returned by fpfi points to a function that has at
+least one parameter, which has type int .
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ function definitions (<A href="
+ #3.7.1">3.7.1</A>), type names (<A href="
+ #3.5.5">3.5.5</A>).
+</FONT></P><H4><A name="3.5.5">3.5.5 Type names</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="type-name">type-name</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #specifier-qualifier-list">specifier-qualifier-list</A></FONT> <FONT class="nonterm"><A href="
+ #abstract-declarator">abstract-declarator</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="abstract-declarator">abstract-declarator</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pointer">pointer</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pointer">pointer</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #direct-abstract-declarator">direct-abstract-declarator</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="direct-abstract-declarator">direct-abstract-declarator</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #abstract-declarator">abstract-declarator</A></FONT> <FONT class="term">)</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #direct-abstract-declarator">direct-abstract-declarator</A><SUB>opt</SUB></FONT> <FONT class="term">[</FONT> <FONT class="nonterm"><A href="
+ #constant-expression">constant-expression</A><SUB>opt</SUB></FONT> <FONT class="term">]</FONT> </P><P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #direct-abstract-declarator">direct-abstract-declarator</A><SUB>opt</SUB></FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #parameter-type-list">parameter-type-list</A><SUB>opt</SUB></FONT> <FONT class="term">)</FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> In several contexts it is desired to specify a type. This is
+accomplished using a type name, which is syntactically a declaration
+for a function or an object of that type that omits the
+identifier.<SUP><A href="
+ #64">64</A></SUP></FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The constructions
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> (a) int
+ (b) int *
+ (c) int *[3]
+ (d) int (*)[3]
+ (e) int *()
+ (f) int (*)(void)
+ (g) int (*const [])(unsigned int, ...)
+</FONT></P></PRE><P>
+<FONT size="-1">name respectively the types (a) int , (b) pointer to int , (c) array
+of three pointers to int , (d) pointer to an array of three int's, (e)
+function with no parameter specification returning a pointer to int ,
+(f) pointer to function with no parameters returning an int , and (g)
+array of an unspecified number of constant pointers to functions, each
+with one parameter that has type unsigned int and an unspecified
+number of other parameters, returning an int .
+</FONT></P></P><H4><A name="3.5.6">3.5.6 Type definitions</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="typedef-name">typedef-name</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> In a declaration whose storage-class specifier is typedef , each
+declarator defines an identifier to be a typedef name that specifies
+the type specified for the identifier in the way described in <A href="
+ #3.5.4">3.5.4</A>
+A typedef declaration does not introduce a new type, only a synonym
+for the type so specified. That is, in the following declarations:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> typedef T type_ident;
+ type_ident D;
+</FONT></P></PRE><P>
+<FONT size="-1">type_ident is defined as a typedef name with the type specified by the
+declaration specifiers in T (known as T ), and the identifier in D has
+the type `` "derived-declarator-type-list T" '' where the
+derived-declarator-type-list is specified by the declarators of D . A
+typedef name shares the same name space as other identifiers declared
+in ordinary declarators. If the identifier is redeclared in an inner
+scope or is declared as a member of a structure or union in the same
+or an inner scope, the type specifiers shall not be omitted in the
+inner declaration.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> After
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> typedef int MILES, KLICKSP();
+ typedef struct { double re, im; } complex;
+</FONT></P></PRE><P>
+<FONT size="-1">the constructions
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> MILES distance;
+ extern KLICKSP *metricp;
+ complex x;
+ complex z, *zp;
+</FONT></P></PRE><P>
+<FONT size="-1">are all valid declarations. The type of distance is int , that of
+metricp is ``pointer to function with no parameter specification
+returning int ,'' and that of x and z is the specified structure; zp
+is a pointer to such a structure. The object distance has a type
+compatible with any other int object.
+</FONT></P><P>
+<FONT size="-1"> After the declarations
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> typedef struct s1 { int x; } t1, *tp1;
+ typedef struct s2 { int x; } t2, *tp2;
+</FONT></P></PRE><P>
+<FONT size="-1">type t1 and the type pointed to by tp1 are compatible. Type t1 is
+also compatible with type struct s1 , but not compatible with the
+types struct s2 , t2 , the type pointed to by tp2 , and int .
+</FONT></P><P>
+<FONT size="-1"> The following constructions
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> typedef signed int t;
+ typedef int plain;
+ struct tag {
+ unsigned t:4;
+ const t:5;
+ plain r:5;
+ };
+</FONT></P></PRE><P>
+<FONT size="-1">declare a typedef name t with type signed int , a typedef name plain
+with type int , and a structure with three bit-field members, one
+named t that contains values in the range [0,15], an unnamed
+const-qualified bit-field which (if it could be accessed) would
+contain values in at least the range [-15,+15], and one named r that
+contains values in the range [0,31] or values in at least the range
+[-15,+15]. (The choice of range is implementation-defined.) If these
+declarations are followed in an inner scope by
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> t f(t (t));
+ long t;
+</FONT></P></PRE><P>
+<FONT size="-1">then a function f is declared with type ``function returning signed
+int with one unnamed parameter with type pointer to function returning
+signed int with one unnamed parameter with type signed int ,'' and an
+identifier t with type long .
+</FONT></P></P><H4><A name="3.5.7">3.5.7 Initialization</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="initializer">initializer</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #assignment-expression">assignment-expression</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">{</FONT> <FONT class="nonterm"><A href="
+ #initializer-list">initializer-list</A></FONT> <FONT class="term">}</FONT> </P><P class="nonterm-defseq">
+<FONT class="term">{</FONT> <FONT class="nonterm"><A href="
+ #initializer-list">initializer-list</A></FONT> <FONT class="term">,</FONT> <FONT class="term">}</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="initializer-list">initializer-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #initializer">initializer</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #initializer-list">initializer-list</A></FONT> <FONT class="term">,</FONT> <FONT class="nonterm"><A href="
+ #initializer">initializer</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> There shall be no more initializers in an initializer list than
+there are objects to be initialized.
+</FONT></P><P>
+<FONT size="-1"> The type of the entity to be initialized shall be an object type or
+an array of unknown size.
+</FONT></P><P>
+<FONT size="-1"> All the expressions in an initializer for an object that has static
+storage duration or in an initializer list for an object that has
+aggregate or union type shall be constant expressions.
+</FONT></P><P>
+<FONT size="-1"> If the declaration of an identifier has block scope, and the
+identifier has external or internal linkage, there shall be no
+initializer for the identifier.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An initializer specifies the initial value stored in an object.
+</FONT></P><P>
+<FONT size="-1"> All unnamed structure or union members are ignored during initialization.
+</FONT></P><P>
+<FONT size="-1"> If an object that has static storage duration is not initialized
+explicitly, it is initialized implicitly as if every member that has
+arithmetic type were assigned 0 and every member that has pointer type
+were assigned a null pointer constant. If an object that has
+automatic storage duration is not initialized explicitly, its value is
+indeterminate.<SUP><A href="
+ #65">65</A></SUP></FONT></P><P>
+<FONT size="-1"> The initializer for a scalar shall be a single expression,
+optionally enclosed in braces. The initial value of the object is
+that of the expression; the same type constraints and conversions as
+for simple assignment apply.
+</FONT></P><P>
+<FONT size="-1"> A brace-enclosed initializer for a union object initializes the
+member that appears first in the declaration list of the union type.
+</FONT></P><P>
+<FONT size="-1"> The initializer for a structure or union object that has automatic
+storage duration either shall be an initializer list as described
+below, or shall be a single expression that has compatible structure
+or union type. In the latter case, the initial value of the object is
+that of the expression.
+</FONT></P><P>
+<FONT size="-1"> The rest of this section deals with initializers for objects that
+have aggregate or union type.
+</FONT></P><P>
+<FONT size="-1"> An array of character type may be initialized by a character string
+literal, optionally enclosed in braces. Successive characters of the
+character string literal (including the terminating null character if
+there is room or if the array is of unknown size) initialize the
+members of the array.
+</FONT></P><P>
+<FONT size="-1"> An array with element type compatible with wchar_t may be
+initialized by a wide string literal, optionally enclosed in braces.
+Successive codes of the wide string literal (including the terminating
+zero-valued code if there is room or if the array is of unknown size)
+initialize the members of the array.
+</FONT></P><P>
+<FONT size="-1"> Otherwise, the initializer for an object that has aggregate type
+shall be a brace-enclosed list of initializers for the members of the
+aggregate, written in increasing subscript or member order; and the
+initializer for an object that has union type shall be a
+brace-enclosed initializer for the first member of the union.
+</FONT></P><P>
+<FONT size="-1"> If the aggregate contains members that are aggregates or unions, or
+if the first member of a union is an aggregate or union, the rules
+apply recursively to the subaggregates or contained unions. If the
+initializer of a subaggregate or contained union begins with a left
+brace, the initializers enclosed by that brace and its matching right
+brace initialize the members of the subaggregate or the first member
+of the contained union. Otherwise, only enough initializers from the
+list are taken to account for the members of the first subaggregate or
+the first member of the contained union; any remaining initializers
+are left to initialize the next member of the aggregate of which the
+current subaggregate or contained union is a part.
+</FONT></P><P>
+<FONT size="-1"> If there are fewer initializers in a list than there are members of
+an aggregate, the remainder of the aggregate shall be initialized
+implicitly the same as objects that have static storage duration.
+</FONT></P><P>
+<FONT size="-1"> If an array of unknown size is initialized, its size is determined
+by the number of initializers provided for its members. At the end of
+its initializer list, the array no longer has incomplete type.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int x[] = { 1, 3, 5 };
+</FONT></P></PRE><P>
+<FONT size="-1">defines and initializes x as a one-dimensional array object that has
+three members, as no size was specified and there are three
+initializers.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> float y[4][3] = {
+ { 1, 3, 5 },
+ { 2, 4, 6 },
+ { 3, 5, 7 },
+ };
+</FONT></P></PRE><P>
+<FONT size="-1">is a definition with a fully bracketed initialization: 1, 3, and 5
+initialize the first row of the array object y[0] , namely y[0][0] ,
+y[0][1] , and y[0][2] . Likewise the next two lines initialize y[1]
+and y[2] . The initializer ends early, so y[3] is initialized with
+zeros. Precisely the same effect could have been achieved by
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> float y[4][3] = {
+ 1, 3, 5, 2, 4, 6, 3, 5, 7
+ };
+</FONT></P></PRE><P>
+<FONT size="-1">The initializer for y[0] does not begin with a left brace, so three
+items from the list are used. Likewise the next three are taken
+successively for y[1] and y[2] . Also,
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> float z[4][3] = {
+ { 1 }, { 2 }, { 3 }, { 4 }
+ };
+</FONT></P></PRE><P>
+<FONT size="-1">initializes the first column of z as specified and initializes the
+rest with zeros.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct { int a[3], b; } w[] = { { 1 }, 2 };
+</FONT></P></PRE><P>
+<FONT size="-1">is a definition with an inconsistently bracketed initialization. It
+defines an array with two member structures: w[0].a[0] is 1 and
+w[1].a[0] is 2; all the other elements are zero.
+</FONT></P><P>
+<FONT size="-1"> The declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> short q[4][3][2] = {
+ { 1 },
+ { 2, 3 },
+ { 4, 5, 6 }
+ };
+</FONT></P></PRE><P>
+<FONT size="-1">contains an incompletely but consistently bracketed initialization.
+It defines a three-dimensional array object: q[0][0][0] is 1,
+q[1][0][0] is 2, q[1][0][1] is 3, and 4, 5, and 6 initialize
+q[2][0][0] , q[2][0][1] , and q[2][1][0] , respectively; all the rest
+are zero. The initializer for q[0][0][0] does not begin with a left
+brace, so up to six items from the current list may be used. There is
+only one, so the values for the remaining five members are initialized
+with zero. Likewise, the initializers for q[1][0][0] and q[2][0][0]
+do not begin with a left brace, so each uses up to six items,
+initializing their respective two-dimensional subaggregates. If there
+had been more than six items in any of the lists, a diagnostic message
+would occur. The same initialization result could have been achieved
+by:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> short q[4][3][2] = {
+ 1, 0, 0, 0, 0, 0,
+ 2, 3, 0, 0, 0, 0,
+ 4, 5, 6
+ };
+</FONT></P></PRE><P>
+<FONT size="-1">or by:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> short q[4][3][2] = {
+ {
+ { 1 },
+ },
+ {
+ { 2, 3 },
+ },
+ {
+ { 4, 5 },
+ { 6 },
+ }
+ };
+</FONT></P></PRE><P>
+<FONT size="-1">in a fully-bracketed form.
+</FONT></P><P>
+<FONT size="-1"> Note that the fully-bracketed and minimally-bracketed forms of
+initialization are, in general, less likely to cause confusion.
+</FONT></P><P>
+<FONT size="-1"> Finally, the declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> char s[] = "abc", t[3] = "abc";
+</FONT></P></PRE><P>
+<FONT size="-1">defines ``plain'' char array objects s and t whose members are
+initialized with character string literals. This declaration is
+identical to
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> char s[] = { 'a', 'b', 'c', '\0' },
+ t[] = { 'a', 'b', 'c' };
+</FONT></P></PRE><P>
+<FONT size="-1">The contents of the arrays are modifiable. On the other hand, the
+declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> char *p = "abc";
+</FONT></P></PRE><P>
+<FONT size="-1">defines p with type ``pointer to char '' that is initialized to point
+to an object with type ``array of char '' whose members are
+initialized with a character string literal. If an attempt is made to
+use p to modify the contents of the array, the behavior is undefined.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ common definitions <stddef.h> (<A href="
+ #4.1.5">4.1.5</A>).
+</FONT></P>
+
+<H3><A name="3.6">3.6 STATEMENTS</A></H3>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="statement">statement</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #labeled-statement">labeled-statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #compound-statement">compound-statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #expression-statement">expression-statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #selection-statement">selection-statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #iteration-statement">iteration-statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #jump-statement">jump-statement</A></FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A statement specifies an action to be performed. Except as
+indicated, statements are executed in sequence.
+</FONT></P><P>
+<FONT size="-1"> A full expression is an expression that is not part of another
+expression. Each of the following is a full expression: an
+initializer; the expression in an expression statement; the
+controlling expression of a selection statement ( if or switch ); the
+controlling expression of a while or do statement; each of the three
+expressions of a for statement; the expression in a return statement.
+The end of a full expression is a sequence point.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ expression and null statements (<A href="
+ #3.6.3">3.6.3</A>), selection
+statements (<A href="
+ #3.6.4">3.6.4</A>), iteration statements (<A href="
+ #3.6.5">3.6.5</A>), the return
+statement (<A href="
+ #3.6.6.4">3.6.6.4</A>).
+</FONT></P><H4><A name="3.6.1">3.6.1 Labeled statements</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="labeled-statement">labeled-statement</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> : <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">case</FONT> <FONT class="nonterm"><A href="
+ #constant-expression">constant-expression</A></FONT> : <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">default</FONT> : <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A case or default label shall appear only in a switch statement.
+Further constraints on such labels are discussed under the switch
+statement.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> Any statement may be preceded by a prefix that declares an
+identifier as a label name. Labels in themselves do not alter the
+flow of control, which continues unimpeded across them.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the goto statement (<A href="
+ #3.6.6.1">3.6.6.1</A>), the switch
+statement (<A href="
+ #3.6.4.2">3.6.4.2</A>).
+</FONT></P><H4><A name="3.6.2">3.6.2 Compound statement, or block</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="compound-statement">compound-statement</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">{</FONT> <FONT class="nonterm"><A href="
+ #declaration-list">declaration-list</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #statement-list">statement-list</A><SUB>opt</SUB></FONT> <FONT class="term">}</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="declaration-list">declaration-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declaration">declaration</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declaration-list">declaration-list</A></FONT> <FONT class="nonterm"><A href="
+ #declaration">declaration</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="statement-list">statement-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #statement-list">statement-list</A></FONT> <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A compound statement (also called a block) allows a set of
+statements to be grouped into one syntactic unit, which may have its
+own set of declarations and initializations (as discussed in
+<A href="
+ #3.1.2.4">3.1.2.4</A>). The initializers of objects that have automatic storage
+duration are evaluated and the values are stored in the objects in the
+order their declarators appear in the translation unit.
+</FONT></P></P><H4><A name="3.6.3">3.6.3 Expression and null statements</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="expression-statement">expression-statement</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #expression">expression</A><SUB>opt</SUB></FONT> <FONT class="term">;</FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The expression in an expression statement is evaluated as a void
+expression for its side effects.<SUP><A href="
+ #66">66</A></SUP></FONT></P><P>
+<FONT size="-1"> A null statement (consisting of just a semicolon) performs no
+operations.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> If a function call is evaluated as an expression statement for its
+side effects only, the discarding of its value may be made explicit by
+converting the expression to a void expression by means of a cast:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int p(int);
+ /*...*/
+ (void)p(0);
+</FONT></P></PRE><P>
+<FONT size="-1"> In the program fragment
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> char *s;
+ /*...*/
+ while (*s++ != '\0')
+ ;
+</FONT></P></PRE><P>
+<FONT size="-1">a null statement is used to supply an empty loop body to the iteration
+statement.
+</FONT></P><P>
+<FONT size="-1"> A null statement may also be used to carry a label just before the
+closing } of a compound statement.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> while (loop1) {
+ /*...*/
+ while (loop2) {
+ /*...*/
+ if (want_out)
+ goto end_loop1;
+ /*...*/
+ }
+ /*...*/
+ end_loop1: ;
+ }
+</FONT></P></PRE></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ iteration statements (<A href="
+ #3.6.5">3.6.5</A>).
+</FONT></P><H4><A name="3.6.4">3.6.4 Selection statements</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="selection-statement">selection-statement</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">if</FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> <FONT class="term">)</FONT> <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">if</FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> <FONT class="term">)</FONT> <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT> <FONT class="term">else</FONT> <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">switch</FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> <FONT class="term">)</FONT> <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A selection statement selects among a set of statements depending
+on the value of a controlling expression.
+</FONT></P></P><H5><A name="3.6.4.1">3.6.4.1 The if statement</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The controlling expression of an if statement shall have scalar type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> In both forms, the first substatement is executed if the expression
+compares unequal to 0. In the else form, the second substatement is
+executed if the expression compares equal to 0. If the first
+substatement is reached via a label, the second substatement is not
+executed.
+</FONT></P><P>
+<FONT size="-1"> An else is associated with the lexically immediately preceding else
+-less if that is in the same block (but not in an enclosed block).
+</FONT></P></P><H5><A name="3.6.4.2">3.6.4.2 The switch statement</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The controlling expression of a switch statement shall have
+integral type. The expression of each case label shall be an integral
+constant expression. No two of the case constant expressions in the
+same switch statement shall have the same value after conversion.
+There may be at most one default label in a switch statement. (Any
+enclosed switch statement may have a default label or case constant
+expressions with values that duplicate case constant expressions in
+the enclosing switch statement.)
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A switch statement causes control to jump to, into, or past the
+statement that is the switch body, depending on the value of a
+controlling expression, and on the presence of a default label and the
+values of any case labels on or in the switch body. A case or default
+label is accessible only within the closest enclosing switch
+statement.
+</FONT></P><P>
+<FONT size="-1"> The integral promotions are performed on the controlling
+expression. The constant expression in each case label is converted
+to the promoted type of the controlling expression. If a converted
+value matches that of the promoted controlling expression, control
+jumps to the statement following the matched case label. Otherwise,
+if there is a default label, control jumps to the labeled statement.
+If no converted case constant expression matches and there is no
+default label, no part of the switch body is executed.
+</FONT></P><P>
+<FONT size="-1">"Implementation limits"
+</FONT></P><P>
+<FONT size="-1"> As discussed previously (<A href="
+ #2.2.4.1">2.2.4.1</A>), the implementation may limit
+the number of case values in a switch statement.
+</FONT></P></P><H4><A name="3.6.5">3.6.5 Iteration statements</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="iteration-statement">iteration-statement</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">while</FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> <FONT class="term">)</FONT> <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">do</FONT> <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT> <FONT class="term">while</FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A></FONT> <FONT class="term">)</FONT> <FONT class="term">;</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">for</FONT> <FONT class="term">(</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A><SUB>opt</SUB></FONT> <FONT class="term">;</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A><SUB>opt</SUB></FONT> <FONT class="term">;</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A><SUB>opt</SUB></FONT> <FONT class="term">)</FONT> <FONT class="nonterm"><A href="
+ #statement">statement</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The controlling expression of an iteration statement shall have scalar type.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> An iteration statement causes a statement called the loop body to
+be executed repeatedly until the controlling expression compares equal
+to 0.
+</FONT></P></P><H5><A name="3.6.5.1">3.6.5.1 The while statement</A></H5>
+<P>
+<FONT size="-1"> The evaluation of the controlling expression takes place before
+each execution of the loop body.
+</FONT></P><H5><A name="3.6.5.2">3.6.5.2 The do statement</A></H5>
+<P>
+<FONT size="-1"> The evaluation of the controlling expression takes place after each
+execution of the loop body.
+</FONT></P><H5><A name="3.6.5.3">3.6.5.3 The for statement</A></H5>
+<P>
+<FONT size="-1"> Except for the behavior of a continue statement in the loop body,
+the statement
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> for ( expression-1 ; expression-2 ; expression-3 ) statement
+</FONT></P></PRE><P>
+<FONT size="-1">and the sequence of statements
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> expression-1 ;
+ while ( expression-2) {
+ statement
+ expression-3 ;
+ }
+</FONT></P></PRE><P>
+<FONT size="-1">are equivalent.<SUP><A href="
+ #67">67</A></SUP> expression-1 expression-2 , expression-3
+</FONT></P><P>
+<FONT size="-1"> Both expression-1 and expression-3 may be omitted. Each is
+evaluated as a void expression. An omitted expression-2 is replaced
+by a nonzero constant.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the continue statement (<A href="
+ #3.6.6.2">3.6.6.2</A>).
+</FONT></P><H4><A name="3.6.6">3.6.6 Jump statements</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="jump-statement">jump-statement</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">goto</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> <FONT class="term">;</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">continue</FONT> <FONT class="term">;</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">break</FONT> <FONT class="term">;</FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">return</FONT> <FONT class="nonterm"><A href="
+ #expression">expression</A><SUB>opt</SUB></FONT> <FONT class="term">;</FONT></P></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A jump statement causes an unconditional jump to another place.
+</FONT></P></P><H5><A name="3.6.6.1">3.6.6.1 The goto statement</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The identifier in a goto statement shall name a label located
+somewhere in the current function.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A goto statement causes an unconditional jump to the statement
+prefixed by the named label in the current function.
+</FONT></P></P><H5><A name="3.6.6.2">3.6.6.2 The continue statement</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A continue statement shall appear only in or as a loop body.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A continue statement causes a jump to the loop-continuation portion
+of the smallest enclosing iteration statement; that is, to the end of
+the loop body. More precisely, in each of the statements
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> while (/*...*/) { do { for (/*...*/) {
+ /*...*/ /*...*/ /*...*/
+ continue; continue; continue;
+ /*...*/ /*...*/ /*...*/
+ contin: ; contin: ; contin: ;
+ } } while (/*...*/); }
+</FONT></P></PRE><P>
+<FONT size="-1">unless the continue statement shown is in an enclosed iteration
+statement (in which case it is interpreted within that statement), it
+is equivalent to goto contin; .<SUP><A href="
+ #68">68</A></SUP></FONT></P></P><H5><A name="3.6.6.3">3.6.6.3 The break statement</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A break statement shall appear only in or as a switch body or loop body.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A break statement terminates execution of the smallest enclosing
+switch or iteration statement.
+</FONT></P></P><H5><A name="3.6.6.4">3.6.6.4 The return statement</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A return statement with an expression shall not appear in a
+function whose return type is void .
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A return statement terminates execution of the current function and
+returns control to its caller. A function may have any number of
+return statements, with and without expressions.
+</FONT></P><P>
+<FONT size="-1"> If a return statement with an expression is executed, the value of
+the expression is returned to the caller as the value of the function
+call expression. If the expression has a type different from that of
+the function in which it appears, it is converted as if it were
+assigned to an object of that type.
+</FONT></P><P>
+<FONT size="-1"> If a return statement without an expression is executed, and the
+value of the function call is used by the caller, the behavior is
+undefined. Reaching the } that terminates a function is equivalent to
+executing a return statement without an expression.
+</FONT></P></P><H3><A name="3.7">3.7 EXTERNAL DEFINITIONS</A></H3>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="translation-unit">translation-unit</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #external-declaration">external-declaration</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #translation-unit">translation-unit</A></FONT> <FONT class="nonterm"><A href="
+ #external-declaration">external-declaration</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="external-declaration">external-declaration</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #function-definition">function-definition</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declaration">declaration</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The storage-class specifiers auto and register shall not appear in
+the declaration specifiers in an external declaration.
+</FONT></P><P>
+<FONT size="-1"> There shall be no more than one external definition for each
+identifier declared with internal linkage in a translation unit.
+Moreover, if an identifier declared with internal linkage is used in
+an expression (other than as a part of the operand of a sizeof
+operator), there shall be exactly one external definition for the
+identifier in the translation unit.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> As discussed in <A href="
+ #2.1.1.1">2.1.1.1</A>, the unit of program text after
+preprocessing is a translation unit, which consists of a sequence of
+external declarations. These are described as ``external'' because
+they appear outside any function (and hence have file scope). As
+discussed in <A href="
+ #3.5">3.5</A>, a declaration that also causes storage to be
+reserved for an object or a function named by the identifier is a
+definition.
+</FONT></P><P>
+<FONT size="-1"> An external definition is an external declaration that is also a
+definition of a function or an object. If an identifier declared with
+external linkage is used in an expression (other than as part of the
+operand of a sizeof operator), somewhere in the entire program there
+shall be exactly one external definition for the identifier.<SUP><A href="
+ #69">69</A></SUP></FONT></P></P><H4><A name="3.7.1">3.7.1 Function definitions</A></H4>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="function-definition">function-definition</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declaration-specifiers">declaration-specifiers</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #declarator">declarator</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #declaration-list">declaration-list</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #compound-statement">compound-statement</A></FONT></P></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The identifier declared in a function definition (which is the name
+of the function) shall have a function type, as specified by the
+declarator portion of the function definition.<SUP><A href="
+ #70">70</A></SUP></FONT></P><P>
+<FONT size="-1"> The return type of a function shall be void or an object type other
+than array.
+</FONT></P><P>
+<FONT size="-1"> The storage-class specifier, if any, in the declaration specifiers
+shall be either extern or static .
+</FONT></P><P>
+<FONT size="-1"> If the declarator includes a parameter type list, the declaration
+of each parameter shall include an identifier (except for the special
+case of a parameter list consisting of a single parameter of type void,
+in which there shall not be an identifier). No declaration list
+shall follow.
+</FONT></P><P>
+<FONT size="-1"> If the declarator includes an identifier list, only the identifiers
+it names shall be declared in the declaration list. An identifier
+declared as a typedef name shall not be redeclared as a parameter.
+The declarations in the declaration list shall contain no
+storage-class specifier other than register and no initializations.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The declarator in a function definition specifies the name of the
+function being defined and the identifiers of its parameters. If the
+declarator includes a parameter type list, the list also specifies the
+types of all the parameters; such a declarator also serves as a
+function prototype for later calls to the same function in the same
+translation unit. If the declarator includes an identifier list,<SUP><A href="
+ #71">71</A></SUP>
+the types of the parameters may be declared in a following declaration
+list. Any parameter that is not declared has type int .
+</FONT></P><P>
+<FONT size="-1"> If a function that accepts a variable number of arguments is
+defined without a parameter type list that ends with the ellipsis
+notation, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> On entry to the function the value of each argument expression
+shall be converted to the type of its corresponding parameter, as if
+by assignment to the parameter. Array expressions and function
+designators as arguments are converted to pointers before the call. A
+declaration of a parameter as ``array of type '' shall be adjusted to
+``pointer to type ,'' and a declaration of a parameter as ``function
+returning type '' shall be adjusted to ``pointer to function returning
+type ,'' as in <A href="
+ #3.2.2.1">3.2.2.1</A> The resulting parameter type shall be an
+object type.
+</FONT></P><P>
+<FONT size="-1"> Each parameter has automatic storage duration. Its identifier is
+an lvalue.<SUP><A href="
+ #72">72</A></SUP> The layout of the storage for parameters is
+unspecified.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> extern int max(int a, int b)
+ {
+ return a > b ? a : b;
+ }
+</FONT></P></PRE><P>
+<FONT size="-1">Here extern is the storage-class specifier and int is the type
+specifier (each of which may be omitted as those are the defaults);
+max(int a, int b) is the function declarator; and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> { return a > b ? a : b; }
+</FONT></P></PRE><P>
+<FONT size="-1">is the function body. The following similar definition uses the
+identifier-list form for the parameter declarations:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> extern int max(a, b)
+ int a, b;
+ {
+ return a > b ? a : b;
+ }
+</FONT></P></PRE><P>
+<FONT size="-1">Here int a, b; is the declaration list for the parameters, which may
+be omitted because those are the defaults. The difference between
+these two definitions is that the first form acts as a prototype
+declaration that forces conversion of the arguments of subsequent
+calls to the function, whereas the second form may not.
+</FONT></P><P>
+<FONT size="-1"> To pass one function to another, one might say
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int f(void);
+ /*...*/
+ g(f);
+</FONT></P></PRE><P>
+<FONT size="-1">Note that f must be declared explicitly in the calling function, as
+its appearance in the expression g(f) was not followed by ( . Then
+the definition of g might read
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> g(int (*funcp)(void))
+ {
+ /*...*/ (*funcp)() /* or funcp() ... */
+ }
+</FONT></P></PRE><P>
+<FONT size="-1">or, equivalently,
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> g(int func(void))
+ {
+ /*...*/ func() /* or (*func)() ... */
+ }
+</FONT></P></PRE></P><H4><A name="3.7.2">3.7.2 External object definitions</A></H4>
+<H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> If the declaration of an identifier for an object has file scope
+and an initializer, the declaration is an external definition for the
+identifier.
+</FONT></P><P>
+<FONT size="-1"> A declaration of an identifier for an object that has file scope
+without an initializer, and without a storage-class specifier or with
+the storage-class specifier static , constitutes a tentative
+definition. If a translation unit contains one or more tentative
+definitions for an identifier, and the translation unit contains no
+external definition for that identifier, then the behavior is exactly
+as if the translation unit contains a file scope declaration of that
+identifier, with the composite type as of the end of the translation
+unit, with an initializer equal to 0.
+</FONT></P><P>
+<FONT size="-1"> If the declaration of an identifier for an object is a tentative
+definition and has internal linkage, the declared type shall not be an
+incomplete type.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> int i1 = 1; /* definition, external linkage */
+ static int i2 = 2; /* definition, internal linkage */
+ extern int i3 = 3; /* definition, external linkage */
+ int i4; /* tentative definition, external linkage */
+ static int i5; /* tentative definition, internal linkage */
+
+ int i1; /* valid tentative definition, refers to previous */
+ int i2; /* <A href="
+ #3.1.2.2">3.1.2.2</A> renders undefined, linkage disagreement */
+ int i3; /* valid tentative definition, refers to previous */
+ int i4; /* valid tentative definition, refers to previous */
+ int i5; /* <A href="
+ #3.1.2.2">3.1.2.2</A> renders undefined, linkage disagreement */
+
+ extern int i1; /* refers to previous, whose linkage is external */
+ extern int i2; /* refers to previous, whose linkage is internal */
+ extern int i3; /* refers to previous, whose linkage is external */
+ extern int i4; /* refers to previous, whose linkage is external */
+ extern int i5; /* refers to previous, whose linkage is internal */
+</FONT></P></PRE></P>
+
+<H3><A name="3.8">3.8 PREPROCESSING DIRECTIVES</A></H3>
+<H6>Syntax</H6>
+<P>
+<P class="syntax-def"> <FONT class="nonterm"><A name="preprocessing-file">preprocessing-file</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #group">group</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="group">group</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #group-part">group-part</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #group">group</A></FONT> <FONT class="nonterm"><A href="
+ #group-part">group-part</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="group-part">group-part</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-tokens">pp-tokens</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #if-section">if-section</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #control-line">control-line</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="if-section">if-section</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #if-group">if-group</A></FONT> <FONT class="nonterm"><A href="
+ #elif-groups">elif-groups</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #else-group">else-group</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #endif-line">endif-line</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="if-group">if-group</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">if</FONT> <FONT class="nonterm"><A href="
+ #constant-expression">constant-expression</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT> <FONT class="nonterm"><A href="
+ #group">group</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">ifdef</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT> <FONT class="nonterm"><A href="
+ #group">group</A><SUB>opt</SUB></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">ifndef</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT> <FONT class="nonterm"><A href="
+ #group">group</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="elif-groups">elif-groups</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #elif-group">elif-group</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #elif-groups">elif-groups</A></FONT> <FONT class="nonterm"><A href="
+ #elif-group">elif-group</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="elif-group">elif-group</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">elif</FONT> <FONT class="nonterm"><A href="
+ #constant-expression">constant-expression</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT> <FONT class="nonterm"><A href="
+ #group">group</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="else-group">else-group</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">else</FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT> <FONT class="nonterm"><A href="
+ #group">group</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="endif-line">endif-line</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">endif</FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="control-line">control-line</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">include</FONT> <FONT class="nonterm"><A href="
+ #pp-tokens">pp-tokens</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">define</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> <FONT class="nonterm"><A href="
+ #replacement-list">replacement-list</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">define</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> <FONT class="nonterm"><A href="
+ #lparen">lparen</A></FONT> <FONT class="nonterm"><A href="
+ #identifier-list">identifier-list</A><SUB>opt</SUB></FONT> <FONT class="term">)</FONT> <FONT class="nonterm"><A href="
+ #replacement-list">replacement-list</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">undef</FONT> <FONT class="nonterm"><A href="
+ #identifier">identifier</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">line</FONT> <FONT class="nonterm"><A href="
+ #pp-tokens">pp-tokens</A></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">error</FONT> <FONT class="nonterm"><A href="
+ #pp-tokens">pp-tokens</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="term">pragma</FONT> <FONT class="nonterm"><A href="
+ #pp-tokens">pp-tokens</A><SUB>opt</SUB></FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="term">#</FONT> <FONT class="nonterm"><A href="
+ #new-line">new-line</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="lparen">lparen</A></FONT>:<BR> <P class="regulartext-nonterm">
+<FONT size="-1">the left-parenthesis character without preceding white-space</FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="replacement-list">replacement-list</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-tokens">pp-tokens</A><SUB>opt</SUB></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="pp-tokens">pp-tokens</A></FONT>:<BR> <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #preprocessing-token">preprocessing-token</A></FONT></P>
+ <P class="nonterm-defseq">
+<FONT class="nonterm"><A href="
+ #pp-tokens">pp-tokens</A></FONT> <FONT class="nonterm"><A href="
+ #preprocessing-token">preprocessing-token</A></FONT></P></P><P class="syntax-def"> <FONT class="nonterm"><A name="new-line">new-line</A></FONT>:<BR> <P class="regulartext-nonterm">
+<FONT size="-1">the new-line character</FONT></P></P></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> A preprocessing directive consists of a sequence of preprocessing
+tokens that begins with a # preprocessing token that is either the
+first character in the source file (optionally after white space
+containing no new-line characters) or that follows white space
+containing at least one new-line character, and is ended by the next
+new-line character.<SUP><A href="
+ #73">73</A></SUP></FONT></P></P><H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The only white-space characters that shall appear between
+preprocessing tokens within a preprocessing directive (from just after
+the introducing # preprocessing token through just before the
+terminating new-line character) are space and horizontal-tab
+(including spaces that have replaced comments in translation phase 3).
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The implementation can process and skip sections of source files
+conditionally, include other source files, and replace macros. These
+capabilities are called preprocessing , because conceptually they
+occur before translation of the resulting translation unit.
+</FONT></P><P>
+<FONT size="-1"> The preprocessing tokens within a preprocessing directive are not
+subject to macro expansion unless otherwise stated.
+</FONT></P></P><H4><A name="3.8.1">3.8.1 Conditional inclusion</A></H4>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The expression that controls conditional inclusion shall be an
+integral constant expression except that: it shall not contain a cast;
+identifiers (including those lexically identical to keywords) are
+interpreted as described below;<SUP><A href="
+ #74">74</A></SUP> and it may contain unary operator
+expressions of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> defined identifier
+ defined ( identifier )
+</FONT></P></PRE><P>
+<FONT size="-1">which evaluate to 1 if the identifier is currently defined as a macro
+name (that is, if it is predefined or if it has been the subject of a
+#define preprocessing directive without an intervening #undef
+directive with the same subject identifier), 0 if it is not.
+</FONT></P><P>
+<FONT size="-1"> Each preprocessing token that remains after all macro replacements
+have occurred shall be in the lexical form of a token.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> Preprocessing directives of the forms
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # if constant-expression new-line group<opt>
+ # elif constant-expression new-line group<opt>
+</FONT></P></PRE><P>
+<FONT size="-1">check whether the controlling constant expression evaluates to
+nonzero.
+</FONT></P><P>
+<FONT size="-1"> Prior to evaluation, macro invocations in the list of preprocessing
+tokens that will become the controlling constant expression are
+replaced (except for those macro names modified by the defined unary
+operator), just as in normal text. If the token defined is generated
+as a result of this replacement process, the behavior is undefined.
+After all replacements are finished, the resulting preprocessing
+tokens are converted into tokens, and then all remaining identifiers
+are replaced with 0 . The resulting tokens comprise the controlling
+constant expression which is evaluated according to the rules of <A href="
+ #3.4">3.4</A>
+using arithmetic that has at least the ranges specified in <A href="
+ #2.2.4.2">2.2.4.2</A>,
+except that int and unsigned int act as if they have the same
+representation as, respectively, long and unsigned long . This
+includes interpreting character constants, which may involve
+converting escape sequences into execution character set members.
+Whether the numeric value for these character constants matches the
+value obtained when an identical character constant occurs in an
+expression (other than within a #if or #elif directive) is
+implementation-defined.<SUP><A href="
+ #75">75</A></SUP> Also, whether a single-character character
+constant may have a negative value is implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> Preprocessing directives of the forms
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # ifdef identifier new-line group<opt>
+ # ifndef identifier new-line group<opt>
+</FONT></P></PRE><P>
+<FONT size="-1">check whether the identifier is or is not currently defined as a macro
+name. Their conditions are equivalent to #if defined identifier and
+#if !defined identifier respectively.
+</FONT></P><P>
+<FONT size="-1"> Each directive's condition is checked in order. If it evaluates to
+false (zero), the group that it controls is skipped: directives are
+processed only through the name that determines the directive in order
+to keep track of the level of nested conditionals; the rest of the
+directives' preprocessing tokens are ignored, as are the other
+preprocessing tokens in the group. Only the first group whose control
+condition evaluates to true (nonzero) is processed. If none of the
+conditions evaluates to true, and there is a #else directive, the
+group controlled by the #else is processed; lacking a #else directive,
+all the groups until the #endif are skipped.<SUP><A href="
+ #76">76</A></SUP></FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ macro replacement (<A href="
+ #3.8.3">3.8.3</A>), source file inclusion
+(<A href="
+ #3.8.2">3.8.2</A>).
+</FONT></P><H4><A name="3.8.2">3.8.2 Source file inclusion</A></H4>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A #include directive shall identify a header or source file that
+can be processed by the implementation.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # include <h-char-sequence> new-line
+</FONT></P></PRE><P>
+<FONT size="-1">searches a sequence of implementation-defined places for a header
+identified uniquely by the specified sequence between the < and >
+delimiters, and causes the replacement of that directive by the entire
+contents of the header. How the places are specified or the header
+identified is implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # include "q-char-sequence" new-line
+</FONT></P></PRE><P>
+<FONT size="-1">causes the replacement of that directive by the entire contents of the
+source file identified by the specified sequence between the
+delimiters. The named source file is searched for in an
+implementation-defined manner. If this search is not supported, or if
+the search fails, the directive is reprocessed as if it read
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # include <h-char-sequence> new-line
+</FONT></P></PRE><P>
+<FONT size="-1">with the identical contained sequence (including > characters, if any)
+from the original directive.
+</FONT></P><P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # include pp-tokens new-line
+</FONT></P></PRE><P>
+<FONT size="-1">(that does not match one of the two previous forms) is permitted. The
+preprocessing tokens after include in the directive are processed just
+as in normal text. (Each identifier currently defined as a macro name
+is replaced by its replacement list of preprocessing tokens.) The
+directive resulting after all replacements shall match one of the two
+previous forms.<SUP><A href="
+ #77">77</A></SUP> The method by which a sequence of preprocessing
+tokens between a < and a > preprocessing token pair or a pair of
+characters is combined into a single header name preprocessing token
+is implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> There shall be an implementation-defined mapping between the
+delimited sequence and the external source file name. The
+implementation shall provide unique mappings for sequences consisting
+of one or more letters (as defined in <A href="
+ #2.2.1">2.2.1</A>) followed by a period (.)
+and a single letter. The implementation may ignore the distinctions
+of alphabetical case and restrict the mapping to six significant
+characters before the period.
+</FONT></P><P>
+<FONT size="-1"> A #include preprocessing directive may appear in a source file that
+has been read because of a #include directive in another file, up to
+an implementation-defined nesting limit (see <A href="
+ #2.2.4.1">2.2.4.1</A>).
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The most common uses of #include preprocessing directives are as in
+the following:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ #include "myprog.h"
+</FONT></P></PRE><P>
+<FONT size="-1"> This example illustrates a macro-replaced #include directive:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #if VERSION == 1
+ #define INCFILE "vers1.h"
+ #elif VERSION == 2
+ #define INCFILE "vers2.h"
+ /* and so on */
+ #else
+ #define INCFILE "versN.h"
+ #endif
+ /*...*/
+ #include INCFILE
+</FONT></P></PRE></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ macro replacement (<A href="
+ #3.8.3">3.8.3</A>).
+</FONT></P><H4><A name="3.8.3">3.8.3 Macro replacement</A></H4>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Two replacement lists are identical if and only if the
+preprocessing tokens in both have the same number, ordering, spelling,
+and white-space separation, where all white-space separations are
+considered identical.
+</FONT></P><P>
+<FONT size="-1"> An identifier currently defined as a macro without use of lparen
+(an object-like macro) may be redefined by another #define
+preprocessing directive provided that the second definition is an
+object-like macro definition and the two replacement lists are
+identical.
+</FONT></P><P>
+<FONT size="-1"> An identifier currently defined as a macro using lparen (a
+function-like macro) may be redefined by another #define preprocessing
+directive provided that the second definition is a function-like macro
+definition that has the same number and spelling of parameters, and
+the two replacement lists are identical.
+</FONT></P><P>
+<FONT size="-1"> The number of arguments in an invocation of a function-like macro
+shall agree with the number of parameters in the macro definition, and
+there shall exist a ) preprocessing token that terminates the
+invocation.
+</FONT></P><P>
+<FONT size="-1"> A parameter identifier in a function-like macro shall be uniquely
+declared within its scope.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The identifier immediately following the define is called the macro
+name. Any white-space characters preceding or following the
+replacement list of preprocessing tokens are not considered part of
+the replacement list for either form of macro.
+</FONT></P><P>
+<FONT size="-1"> If a # preprocessing token, followed by an identifier, occurs
+lexically at the point at which a preprocessing directive could begin,
+the identifier is not subject to macro replacement.
+</FONT></P><P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # define identifier replacement-list new-line
+</FONT></P></PRE><P>
+<FONT size="-1">defines an object-like macro that causes each subsequent instance of
+the macro name<SUP><A href="
+ #78">78</A></SUP> to be replaced by the replacement list of
+preprocessing tokens that constitute the remainder of the directive.
+The replacement list is then rescanned for more macro names as
+specified below.
+</FONT></P><P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # define identifier lparen identifier-list<opt> )
+ replacement-list new-line
+</FONT></P></PRE><P>
+<FONT size="-1">defines a function-like macro with arguments, similar syntactically to
+a function call. The parameters are specified by the optional list of
+identifiers, whose scope extends from their declaration in the
+identifier list until the new-line character that terminates the
+#define preprocessing directive. Each subsequent instance of the
+function-like macro name followed by a ( as the next preprocessing
+token introduces the sequence of preprocessing tokens that is replaced
+by the replacement list in the definition (an invocation of the
+macro). The replaced sequence of preprocessing tokens is terminated
+by the matching ) preprocessing token, skipping intervening matched
+pairs of left and right parenthesis preprocessing tokens. Within the
+sequence of preprocessing tokens making up an invocation of a
+function-like macro, new-line is considered a normal white-space
+character.
+</FONT></P><P>
+<FONT size="-1"> The sequence of preprocessing tokens bounded by the outside-most
+matching parentheses forms the list of arguments for the function-like
+macro. The individual arguments within the list are separated by
+comma preprocessing tokens, but comma preprocessing tokens bounded by
+nested parentheses do not separate arguments. If (before argument
+substitution) any argument consists of no preprocessing tokens, the
+behavior is undefined. If there are sequences of preprocessing tokens
+within the list of arguments that would otherwise act as preprocessing
+directives, the behavior is undefined.
+</FONT></P></P><H5><A name="3.8.3.1">3.8.3.1 Argument substitution</A></H5>
+<P>
+<FONT size="-1"> After the arguments for the invocation of a function-like macro
+have been identified, argument substitution takes place. A parameter
+in the replacement list, unless preceded by a # or ## preprocessing
+token or followed by a ## preprocessing token (see below), is replaced
+by the corresponding argument after all macros contained therein have
+been expanded. Before being substituted, each argument's
+preprocessing tokens are completely macro replaced as if they formed
+the rest of the source file; no other preprocessing tokens are
+available.
+</FONT></P><H5><A name="3.8.3.2">3.8.3.2 The # operator</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> Each # preprocessing token in the replacement list for a
+function-like macro shall be followed by a parameter as the next
+preprocessing token in the replacement list.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> If, in the replacement list, a parameter is immediately preceded by
+a # preprocessing token, both are replaced by a single character
+string literal preprocessing token that contains the spelling of the
+preprocessing token sequence for the corresponding argument. Each
+occurrence of white space between the argument's preprocessing tokens
+becomes a single space character in the character string literal.
+White space before the first preprocessing token and after the last
+preprocessing token comprising the argument is deleted. Otherwise,
+the original spelling of each preprocessing token in the argument is
+retained in the character string literal, except for special handling
+for producing the spelling of string literals and character constants:
+a \ character is inserted before each and \ character of a character
+constant or string literal (including the delimiting characters). If
+the replacement that results is not a valid character string literal,
+the behavior is undefined. The order of evaluation of # and ##
+operators is unspecified.
+</FONT></P></P><H5><A name="3.8.3.3">3.8.3.3 The ## operator</A></H5>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> A ## preprocessing token shall not occur at the beginning or at the
+end of a replacement list for either form of macro definition.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> If, in the replacement list, a parameter is immediately preceded or
+followed by a ## preprocessing token, the parameter is replaced by the
+corresponding argument's preprocessing token sequence.
+</FONT></P><P>
+<FONT size="-1"> For both object-like and function-like macro invocations, before
+the replacement list is reexamined for more macro names to replace,
+each instance of a ## preprocessing token in the replacement list (not
+from an argument) is deleted and the preceding preprocessing token is
+concatenated with the following preprocessing token. If the result is
+not a valid preprocessing token, the behavior is undefined. The
+resulting token is available for further macro replacement. The order
+of evaluation of ## operators is unspecified.
+</FONT></P></P><H5><A name="3.8.3.4">3.8.3.4 Rescanning and further replacement</A></H5>
+<P>
+<FONT size="-1"> After all parameters in the replacement list have been substituted,
+the resulting preprocessing token sequence is rescanned with the rest
+of the source file's preprocessing tokens for more macro names to
+replace.
+</FONT></P><P>
+<FONT size="-1"> If the name of the macro being replaced is found during this scan
+of the replacement list (not including the rest of the source file's
+preprocessing tokens), it is not replaced. Further, if any nested
+replacements encounter the name of the macro being replaced, it is not
+replaced. These nonreplaced macro name preprocessing tokens are no
+longer available for further replacement even if they are later
+(re)examined in contexts in which that macro name preprocessing token
+would otherwise have been replaced.
+</FONT></P><P>
+<FONT size="-1"> The resulting completely macro-replaced preprocessing token
+sequence is not processed as a preprocessing directive even if it
+resembles one.
+</FONT></P><H5><A name="3.8.3.5">3.8.3.5 Scope of macro definitions</A></H5>
+<P>
+<FONT size="-1"> A macro definition lasts (independent of block structure) until a
+corresponding #undef directive is encountered or (if none is
+encountered) until the end of the translation unit.
+</FONT></P><P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # undef identifier new-line
+</FONT></P></PRE><P>
+<FONT size="-1">causes the specified identifier no longer to be defined as a macro
+name. It is ignored if the specified identifier is not currently
+defined as a macro name.
+</FONT></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The simplest use of this facility is to define a ``manifest
+constant,'' as in
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define TABSIZE 100
+
+ int table[TABSIZE];
+</FONT></P></PRE><P>
+<FONT size="-1"> The following defines a function-like macro whose value is the
+maximum of its arguments. It has the advantages of working for any
+compatible types of the arguments and of generating in-line code
+without the overhead of function calling. It has the disadvantages of
+evaluating one or the other of its arguments a second time (including
+side effects) and of generating more code than a function if invoked
+several times.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define max(a, b) ((a) > (b) ? (a) : (b))
+</FONT></P></PRE><P>
+<FONT size="-1">The parentheses ensure that the arguments and the resulting expression
+are bound properly.
+</FONT></P><P>
+<FONT size="-1"> To illustrate the rules for redefinition and reexamination, the
+sequence
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define x 3
+ #define f(a) f(x * (a))
+ #undef x
+ #define x 2
+ #define g f
+ #define z z[0]
+ #define h g(~
+ #define m(a) a(w)
+ #define w 0,1
+ #define t(a) a
+
+ f(y+1) + f(f(z)) % t(t(g)(0) + t)(1);
+ g(x+(3,4)-w) | h 5) & m
+ (f)^m(m);
+</FONT></P></PRE><P>
+<FONT size="-1">results in
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> f(2 * (y+1)) + f(2 * (f(2 * (z[0])))) % f(2 * (0)) + t(1);
+ f(2 * (2+(3,4)-0,1)) | f(2 * (~ 5)) & f(2 * (0,1))^m(0,1);
+</FONT></P></PRE><P>
+<FONT size="-1"> To illustrate the rules for creating character string literals and
+concatenating tokens, the sequence
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define str(s) # s
+ #define xstr(s) str(s)
+ #define debug(s, t) printf("x" # s "= %d, x" # t "= %s", \
+ x ## s, x ## t)
+ #define INCFILE(n) vers ## n /* from previous #include example */
+ #define glue(a, b) a ## b
+ #define xglue(a, b) glue(a, b)
+ #define HIGHLOW "hello"
+ #define LOW LOW ", world"
+
+ debug(1, 2);
+ fputs(str(strncmp("abc\0d", "abc", '\4') /* this goes away */
+ == 0) str(: @\n), s);
+ #include xstr(INCFILE(2).h)
+ glue(HIGH, LOW);
+ xglue(HIGH, LOW)
+</FONT></P></PRE><P>
+<FONT size="-1">results in
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> printf("x" "1" "= %d, x" "2" "= %s", x1, x2);
+ fputs("strncmp(\"abc\\0d\", \"abc\", '\\4') == 0" ": @\n", s);
+ #include "vers2.h" (after macro replacement, before file access)
+ "hello";
+ "hello" ", world"
+</FONT></P></PRE><P>
+<FONT size="-1">or, after concatenation of the character string literals,
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> printf("x1= %d, x2= %s", x1, x2);
+ fputs("strncmp(\"abc\\0d\", \"abc\", '\\4') == 0: @\n", s);
+ #include "vers2.h" (after macro replacement, before file access)
+ "hello";
+ "hello, world"
+</FONT></P></PRE><P>
+<FONT size="-1">Space around the # and ## tokens in the macro definition is optional.
+</FONT></P><P>
+<FONT size="-1"> And finally, to demonstrate the redefinition rules, the following
+sequence is valid.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define OBJ_LIKE (1-1)
+ #define OBJ_LIKE /* white space */ (1-1) /* other */
+ #define FTN_LIKE(a) ( a )
+ #define FTN_LIKE( a )( /* note the white space */ \
+ a /* other stuff on this line
+ */ )
+</FONT></P></PRE><P>
+<FONT size="-1">But the following redefinitions are invalid:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define OBJ_LIKE (0) /* different token sequence */
+ #define OBJ_LIKE (1 - 1) /* different white space */
+ #define FTN_LIKE(b) ( a ) /* different parameter usage */
+ #define FTN_LIKE(b) ( b ) /* different parameter spelling */
+</FONT></P></PRE></P><H4><A name="3.8.4">3.8.4 Line control</A></H4>
+<H6>Constraints</H6>
+<P>
+<P>
+<FONT size="-1"> The string literal of a #line directive, if present, shall be a
+character string literal.
+</FONT></P></P><H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> The line number of the current source line is one greater than the
+number of new-line characters read or introduced in translation phase
+1 (<A href="
+ #2.1.1.2">2.1.1.2</A>) while processing the source file to the current token.
+</FONT></P><P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # line digit-sequence new-line
+</FONT></P></PRE><P>
+<FONT size="-1">causes the implementation to behave as if the following sequence of
+source lines begins with a source line that has a line number as
+specified by the digit sequence (interpreted as a decimal integer).
+</FONT></P><P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # line digit-sequence " s-char-sequence<opt>" new-line
+</FONT></P></PRE><P>
+<FONT size="-1">sets the line number similarly and changes the presumed name of the
+source file to be the contents of the character string literal.
+</FONT></P><P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # line pp-tokens new-line
+</FONT></P></PRE><P>
+<FONT size="-1">(that does not match one of the two previous forms) is permitted. The
+preprocessing tokens after line on the directive are processed just as
+in normal text (each identifier currently defined as a macro name is
+replaced by its replacement list of preprocessing tokens). The
+directive resulting after all replacements shall match one of the two
+previous forms and is then processed as appropriate.
+</FONT></P></P><H4><A name="3.8.5">3.8.5 Error directive</A></H4>
+<H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # error pp-tokens<opt> new-line
+</FONT></P></PRE><P>
+<FONT size="-1">causes the implementation to produce a diagnostic message that
+includes the specified sequence of preprocessing tokens.
+</FONT></P></P><H4><A name="3.8.6">3.8.6 Pragma directive</A></H4>
+<H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # pragma pp-tokens<opt> new-line
+</FONT></P></PRE><P>
+<FONT size="-1">causes the implementation to behave in an implementation-defined
+manner. Any pragma that is not recognized by the implementation is
+ignored.
+</FONT></P></P><H4><A name="3.8.7">3.8.7 Null directive</A></H4>
+<H6>Semantics</H6>
+<P>
+<P>
+<FONT size="-1"> A preprocessing directive of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> # new-line
+</FONT></P></PRE><P>
+<FONT size="-1">has no effect.
+</FONT></P></P><H4><A name="3.8.8">3.8.8 Predefined macro names</A></H4>
+<P>
+<FONT size="-1"> The following macro names shall be defined by the implementation:
+The line number of the current source line (a decimal constant). The
+presumed name of the source file (a character string literal). The
+date of translation of the source file (a character string literal of
+the form Mmm dd yyyy , where the names of the months are the same as
+those generated by the asctime function, and the first character of dd
+is a space character if the value is less than 10). If the date of
+translation is not available, an implementation-defined valid date
+shall be supplied. The time of translation of the source file (a
+character string literal of the form hh:mm:ss as in the time generated
+by the asctime function). If the time of translation is not
+available, an implementation-defined valid time shall be supplied.
+the decimal constant 1.<SUP><A href="
+ #79">79</A></SUP></FONT></P><P>
+<FONT size="-1"> The values of the predefined macros (except for __LINE__ and
+__FILE__ ) remain constant throughout the translation unit.
+</FONT></P><P>
+<FONT size="-1"> None of these macro names, nor the identifier defined , shall be
+the subject of a #define or a #undef preprocessing directive. All
+predefined macro names shall begin with a leading underscore followed
+by an upper-case letter or a second underscore.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the asctime function (<A href="
+ #4.12.3.1">4.12.3.1</A>).
+</FONT></P>
+
+<H3><A name="3.9">3.9 FUTURE LANGUAGE DIRECTIONS</A></H3>
+<H4><A name="3.9.1">3.9.1 External names</A></H4>
+<P>
+<FONT size="-1"> Restriction of the significance of an external name to fewer than
+31 characters or to only one case is an obsolescent feature that is a
+concession to existing implementations.
+</FONT></P><H4><A name="3.9.2">3.9.2 Character escape sequences</A></H4>
+<P>
+<FONT size="-1"> Lower-case letters as escape sequences are reserved for future
+standardization. Other characters may be used in extensions.
+</FONT></P><H4><A name="3.9.3">3.9.3 Storage-class specifiers</A></H4>
+<P>
+<FONT size="-1"> The placement of a storage-class specifier other than at the
+beginning of the declaration specifiers in a declaration is an
+obsolescent feature.
+</FONT></P><H4><A name="3.9.4">3.9.4 Function declarators</A></H4>
+<P>
+<FONT size="-1"> The use of function declarators with empty parentheses (not
+prototype-format parameter type declarators) is an obsolescent
+feature.
+</FONT></P><H4><A name="3.9.5">3.9.5 Function definitions</A></H4>
+<P>
+<FONT size="-1"> The use of function definitions with separate parameter identifier
+and declaration lists (not prototype-format parameter type and
+identifier declarators) is an obsolescent feature.
+</FONT></P><H2><A name="4.">4. LIBRARY</A></H2>
+<H3><A name="4.1">4.1 INTRODUCTION</A></H3>
+<H4><A name="4.1.1">4.1.1 Definitions of terms</A></H4>
+<P>
+<FONT size="-1"> A string is a contiguous sequence of characters terminated by and
+including the first null character. It is represented by a pointer to
+its initial (lowest addressed) character and its length is the number
+of characters preceding the null character.
+</FONT></P><P>
+<FONT size="-1"> A letter is a printing character in the execution character set
+corresponding to any of the 52 required lower-case and upper-case
+letters in the source character set, listed in <A href="
+ #2.2.1">2.2.1</A></FONT></P><P>
+<FONT size="-1"> The decimal-point character is the character used by functions that
+convert floating-point numbers to or from character sequences to
+denote the beginning of the fractional part of such character
+sequences.<SUP><A href="
+ #80">80</A></SUP> It is represented in the text and examples by a period,
+but may be changed by the setlocale function.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ character handling (<A href="
+ #4.3">4.3</A>), the setlocale function
+(<A href="
+ #4.4.1.1">4.4.1.1</A>).
+</FONT></P><H4><A name="4.1.2">4.1.2 Standard headers</A></H4>
+<P>
+<FONT size="-1"> Each library function is declared in a header,<SUP><A href="
+ #81">81</A></SUP> whose contents
+are made available by the #include preprocessing directive. The
+header declares a set of related functions, plus any necessary types
+and additional macros needed to facilitate their use. Each header
+declares and defines only those identifiers listed in its associated
+section. All external identifiers declared in any of the headers are
+reserved, whether or not the associated header is included. All
+external identifiers that begin with an underscore are reserved. All
+other identifiers that begin with an underscore and either an
+upper-case letter or another underscore are reserved. If the program
+defines an external identifier with the same name as a reserved
+external identifier, even in a semantically equivalent form, the
+behavior is undefined.<SUP><A href="
+ #82">82</A></SUP></FONT></P><P>
+<FONT size="-1"> The standard headers are
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> <assert.h> <locale.h> <stddef.h>
+ <ctype.h> <math.h> <stdio.h>
+ <errno.h> <setjmp.h> <stdlib.h>
+ <float.h> <signal.h> <string.h>
+ <limits.h> <stdarg.h> <time.h>
+</FONT></P></PRE><P>
+<FONT size="-1"> If a file with the same name as one of the above < and > delimited
+sequences, not provided as part of the implementation, is placed in
+any of the standard places for a source file to be included, the
+behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> Headers may be included in any order; each may be included more
+than once in a given scope, with no effect different from being
+included only once, except that the effect of including <assert.h>
+depends on the definition of NDEBUG . If used, a header shall be
+included outside of any external declaration or definition, and it
+shall first be included before the first reference to any of the
+functions or objects it declares, or to any of the types or macros it
+defines. Furthermore, the program shall not have any macros with
+names lexically identical to keywords currently defined prior to the
+inclusion.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ diagnostics (<A href="
+ #4.2">4.2</A>).
+</FONT></P><H4><A name="4.1.3">4.1.3 Errors <errno.h></A></H4>
+<P>
+<FONT size="-1"> The header <errno.h> defines several macros, all relating to the
+reporting of error conditions.
+</FONT></P><P>
+<FONT size="-1"> The macros are
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> EDOM
+ ERANGE
+</FONT></P></PRE><P>
+<FONT size="-1">which expand to distinct nonzero integral constant expressions; and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> errno
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to a modifiable lvalue<SUP><A href="
+ #83">83</A></SUP> that has type int , the value
+of which is set to a positive error number by several library
+functions. It is unspecified whether errno is a macro or an
+identifier declared with external linkage. If a macro definition is
+suppressed in order to access an actual object, or a program defines
+an external identifier with the name errno , the behavior is
+undefined.
+</FONT></P><P>
+<FONT size="-1"> The value of errno is zero at program startup, but is never set to
+zero by any library function.<SUP><A href="
+ #84">84</A></SUP> The value of errno may be set to
+nonzero by a library function call whether or not there is an error,
+provided the use of errno is not documented in the description of the
+function in the Standard.
+</FONT></P><P>
+<FONT size="-1"> Additional macro definitions, beginning with E and a digit or E and
+an upper-case letter,<SUP><A href="
+ #85">85</A></SUP> may also be specified by the implementation.
+</FONT></P><H4><A name="4.1.4">4.1.4 Limits <float.h> and <limits.h></A></H4>
+<P>
+<FONT size="-1"> The headers <float.h> and <limits.h> define several macros that
+expand to various limits and parameters.
+</FONT></P><P>
+<FONT size="-1"> The macros, their meanings, and their minimum magnitudes are listed
+in <A href="
+ #2.2.4.2">2.2.4.2</A></FONT></P><H4><A name="4.1.5">4.1.5 Common definitions <stddef.h></A></H4>
+<P>
+<FONT size="-1"> The following types and macros are defined in the standard header
+<stddef.h> . Some are also defined in other headers, as noted in
+their respective sections.
+</FONT></P><P>
+<FONT size="-1"> The types are
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> ptrdiff_t
+</FONT></P></PRE><P>
+<FONT size="-1">which is the signed integral type of the result of subtracting two
+pointers;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> size_t
+</FONT></P></PRE><P>
+<FONT size="-1">which is the unsigned integral type of the result of the sizeof
+operator; and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> wchar_t
+</FONT></P></PRE><P>
+<FONT size="-1">which is an integral type whose range of values can represent distinct
+codes for all members of the largest extended character set specified
+among the supported locales; the null character shall have the code
+value zero and each member of the basic character set defined in
+<A href="
+ #2.2.1">2.2.1</A> shall have a code value equal to its value when used as the
+lone character in an integer character constant.
+</FONT></P><P>
+<FONT size="-1"> The macros are
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> NULL
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to an implementation-defined null pointer constant; and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> offsetof( type, member-designator)
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to an integral constant expression that has type size_t,
+the value of which is the offset in bytes, to the structure member
+(designated by member-designator ), from the beginning of its
+structure (designated by type ). The member-designator shall be such
+that given
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> static type t;
+</FONT></P></PRE><P>
+<FONT size="-1">then the expression &(t. member-designator ) evaluates to an address
+constant. (If the specified member is a bit-field, the behavior is
+undefined.)
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ localization (<A href="
+ #4.4">4.4</A>).
+</FONT></P><H4><A name="4.1.6">4.1.6 Use of library functions</A></H4>
+<P>
+<FONT size="-1"> Each of the following statements applies unless explicitly stated
+otherwise in the detailed descriptions that follow. If an argument to
+a function has an invalid value (such as a value outside the domain of
+the function, or a pointer outside the address space of the program,
+or a null pointer), the behavior is undefined. Any function declared
+in a header may be implemented as a macro defined in the header, so a
+library function should not be declared explicitly if its header is
+included. Any macro definition of a function can be suppressed
+locally by enclosing the name of the function in parentheses, because
+the name is then not followed by the left parenthesis that indicates
+expansion of a macro function name. For the same syntactic reason, it
+is permitted to take the address of a library function even if it is
+also defined as a macro.<SUP><A href="
+ #86">86</A></SUP> The use of #undef to remove any macro
+definition will also ensure that an actual function is referred to.
+Any invocation of a library function that is implemented as a macro
+will expand to code that evaluates each of its arguments exactly once,
+fully protected by parentheses where necessary, so it is generally
+safe to use arbitrary expressions as arguments. Likewise, those
+function-like macros described in the following sections may be
+invoked in an expression anywhere a function with a compatible return
+type could be called.<SUP><A href="
+ #87">87</A></SUP></FONT></P><P>
+<FONT size="-1"> Provided that a library function can be declared without reference
+to any type defined in a header, it is also permissible to declare the
+function, either explicitly or implicitly, and use it without
+including its associated header. If a function that accepts a
+variable number of arguments is not declared (explicitly or by
+including its associated header), the behavior is undefined.
+</FONT></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The function atoi may be used in any of several ways:
+</FONT></P><P>
+<FONT size="-1"> * by use of its associated header (possibly generating a macro expansion)
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ const char *str;
+ /*...*/
+ i = atoi(str);
+</FONT></P></PRE><P>
+<FONT size="-1"> * by use of its associated header (assuredly generating a true
+function reference)
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ #undef atoi
+ const char *str;
+ /*...*/
+ i = atoi(str);
+</FONT></P></PRE><P>
+<FONT size="-1">or
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ const char *str;
+ /*...*/
+ i = (atoi)(str);
+</FONT></P></PRE><P>
+<FONT size="-1"> * by explicit declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> extern int atoi(const char *);
+ const char *str;
+ /*...*/
+ i = atoi(str);
+</FONT></P></PRE><P>
+<FONT size="-1"> * by implicit declaration
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> const char *str;
+ /*...*/
+ i = atoi(str);
+</FONT></P></PRE></P><H3><A name="4.2">4.2 DIAGNOSTICS <assert.h></A></H3>
+<P>
+<FONT size="-1"> The header <assert.h> defines the assert macro and refers to
+another macro,
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> NDEBUG
+</FONT></P></PRE><P>
+<FONT size="-1">which is not defined by <assert.h> . If NDEBUG is defined as a macro
+name at the point in the source file where <assert.h> is included, the
+assert macro is defined simply as
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define assert(ignore) ((void)0)
+</FONT></P></PRE><P>
+<FONT size="-1"> The assert macro shall be implemented as a macro, not as an actual
+function. If the macro definition is suppressed in order to access an
+actual function, the behavior is undefined.
+</FONT></P><H4><A name="4.2.1">4.2.1 Program diagnostics</A></H4>
+<H5><A name="4.2.1.1">4.2.1.1 The assert macro</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <assert.h>
+ void assert(int expression);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The assert macro puts diagnostics into programs. When it is
+executed, if expression is false (that is, compares equal to 0), the
+assert macro writes information about the particular call that failed
+(including the text of the argument, the name of the source file, and
+the source line number EM the latter are respectively the values of
+the preprocessing macros __FILE__ and __LINE__ ) on the standard error
+file in an implementation-defined format.<SUP><A href="
+ #88">88</A></SUP>
+ expression , xyz , nnn It then calls the abort function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The assert macro returns no value.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the abort function (<A href="
+ #4.10.4.1">4.10.4.1</A>).
+</FONT></P><H3><A name="4.3">4.3 CHARACTER HANDLING <ctype.h></A></H3>
+<P>
+<FONT size="-1"> The header <ctype.h> declares several functions useful for testing
+and mapping characters.<SUP><A href="
+ #89">89</A></SUP> In all cases the argument is an int , the
+value of which shall be representable as an unsigned char or shall
+equal the value of the macro EOF . If the argument has any other
+value, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> The behavior of these functions is affected by the current locale.
+Those functions that have no implementation-defined aspects in the C
+locale are noted below.
+</FONT></P><P>
+<FONT size="-1"> The term printing character refers to a member of an
+implementation-defined set of characters, each of which occupies one
+printing position on a display device; the term control character
+refers to a member of an implementation-defined set of characters that
+are not printing characters.<SUP><A href="
+ #90">90</A></SUP></FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ EOF (<A href="
+ #4.9.1">4.9.1</A>), localization (<A href="
+ #4.4">4.4</A>).
+</FONT></P><H4><A name="4.3.1">4.3.1 Character testing functions</A></H4>
+<P>
+<FONT size="-1"> The functions in this section return nonzero (true) if and only if
+the value of the argument c conforms to that in the description of the
+function.
+</FONT></P><H5><A name="4.3.1.1">4.3.1.1 The isalnum function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int isalnum(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The isalnum function tests for any character for which isalpha or
+isdigit is true.
+</FONT></P></P><H5><A name="4.3.1.2">4.3.1.2 The isalpha function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int isalpha(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The isalpha function tests for any character for which isupper or
+islower is true, or any of an implementation-defined set of characters
+for which none of iscntrl , isdigit , ispunct , or isspace is true.
+In the C locale, isalpha returns true only for the characters for
+which isupper or islower is true.
+</FONT></P></P><H5><A name="4.3.1.3">4.3.1.3 The iscntrl function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int iscntrl(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The iscntrl function tests for any control character.
+</FONT></P></P><H5><A name="4.3.1.4">4.3.1.4 The isdigit function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int isdigit(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The isdigit function tests for any decimal-digit character (as
+defined in <A href="
+ #2.2.1">2.2.1</A>).
+</FONT></P></P><H5><A name="4.3.1.5">4.3.1.5 The isgraph function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int isgraph(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The isgraph function tests for any printing character except space (' ').
+</FONT></P></P><H5><A name="4.3.1.6">4.3.1.6 The islower function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int islower(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The islower function tests for any lower-case letter or any of an
+implementation-defined set of characters for which none of iscntrl ,
+isdigit , ispunct , or isspace is true. In the C locale, islower
+returns true only for the characters defined as lower-case letters (as
+defined in <A href="
+ #2.2.1">2.2.1</A>).
+</FONT></P></P><H5><A name="4.3.1.7">4.3.1.7 The isprint function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int isprint(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The isprint function tests for any printing character including
+space (' ').
+</FONT></P></P><H5><A name="4.3.1.8">4.3.1.8 The ispunct function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int ispunct(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The ispunct function tests for any printing character except space
+(' ') or a character for which isalnum is true.
+</FONT></P></P><H5><A name="4.3.1.9">4.3.1.9 The isspace function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int isspace(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The isspace function tests for the standard white-space characters
+or for any of an implementation-defined set of characters for which
+isalnum is false. The standard white-space characters are the
+following: space (' '), form feed ('\f'), new-line ('\n'), carriage
+return ('\r'), horizontal tab ('\t'), and vertical tab ('\v'). In the
+C locale, isspace returns true only for the standard white-space
+characters.
+</FONT></P></P><H5><A name="4.3.1.10">4.3.1.10 The isupper function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int isupper(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The isupper function tests for any upper-case letter or any of an
+implementation-defined set of characters for which none of iscntrl ,
+isdigit , ispunct , or isspace is true. In the C locale, isupper
+returns true only for the characters defined as upper-case letters (as
+defined in <A href="
+ #2.2.1">2.2.1</A>).
+</FONT></P></P><H5><A name="4.3.1.11">4.3.1.11 The isxdigit function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int isxdigit(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The isxdigit function tests for any hexadecimal-digit character (as
+defined in <A href="
+ #3.1.3.2">3.1.3.2</A>).
+</FONT></P></P><H4><A name="4.3.2">4.3.2 Character case mapping functions</A></H4>
+<H5><A name="4.3.2.1">4.3.2.1 The tolower function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int tolower(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The tolower function converts an upper-case letter to the
+corresponding lower-case letter.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If the argument is an upper-case letter, the tolower function
+returns the corresponding lower-case letter if there is one; otherwise
+the argument is returned unchanged. In the C locale, tolower maps
+only the characters for which isupper is true to the corresponding
+characters for which islower is true.
+</FONT></P></P><H5><A name="4.3.2.2">4.3.2.2 The toupper function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <ctype.h>
+ int toupper(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The toupper function converts a lower-case letter to the corresponding upper-case letter.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If the argument is a lower-case letter, the toupper function
+returns the corresponding upper-case letter if there is one; otherwise
+the argument is returned unchanged. In the C locale, toupper maps
+only the characters for which islower is true to the corresponding
+characters for which isupper is true.
+</FONT></P></P>
+
+<H3><A name="4.4">4.4 LOCALIZATION <locale.h></A></H3>
+<P>
+<FONT size="-1"> The header <locale.h> declares two functions, one type, and defines
+several macros.
+</FONT></P><P>
+<FONT size="-1"> The type is
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct lconv
+</FONT></P></PRE><P>
+<FONT size="-1">which contains members related to the formatting of numeric values.
+The structure shall contain at least the following members, in any
+order. The semantics of the members and their normal ranges is
+explained in <A href="
+ #4.4.2.1">4.4.2.1</A> In the C locale, the members shall have the
+values specified in the comments.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> char *decimal_point; /* "." */
+ char *thousands_sep; /* "" */
+ char *grouping; /* "" */
+ char *int_curr_symbol; /* "" */
+ char *currency_symbol; /* "" */
+ char *mon_decimal_point; /* "" */
+ char *mon_thousands_sep; /* "" */
+ char *mon_grouping; /* "" */
+ char *positive_sign; /* "" */
+ char *negative_sign; /* "" */
+ char int_frac_digits; /* CHAR_MAX */
+ char frac_digits; /* CHAR_MAX */
+ char p_cs_precedes; /* CHAR_MAX */
+ char p_sep_by_space; /* CHAR_MAX */
+ char n_cs_precedes; /* CHAR_MAX */
+ char n_sep_by_space; /* CHAR_MAX */
+ char p_sign_posn; /* CHAR_MAX */
+ char n_sign_posn; /* CHAR_MAX */
+</FONT></P></PRE><P>
+<FONT size="-1"> The macros defined are NULL (described in <A href="
+ #4.1.5">4.1.5</A>); and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> LC_ALL
+ LC_COLLATE
+ LC_CTYPE
+ LC_MONETARY
+ LC_NUMERIC
+ LC_TIME
+</FONT></P></PRE><P>
+<FONT size="-1">which expand to distinct integral constant expressions, suitable for
+use as the first argument to the setlocale function. Additional macro
+definitions, beginning with the characters LC_ and an upper-case
+letter,<SUP><A href="
+ #91">91</A></SUP> may also be specified by the implementation.
+</FONT></P><H4><A name="4.4.1">4.4.1 Locale control</A></H4>
+<H5><A name="4.4.1.1">4.4.1.1 The setlocale function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <locale.h>
+ char *setlocale(int category, const char *locale);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The setlocale function selects the appropriate portion of the
+program's locale as specified by the category and locale arguments.
+The setlocale function may be used to change or query the program's
+entire current locale or portions thereof. The value LC_ALL for
+category names the program's entire locale; the other values for
+category name only a portion of the program's locale. LC_COLLATE
+affects the behavior of the strcoll and strxfrm functions. LC_CTYPE
+affects the behavior of the character handling functions<SUP><A href="
+ #92">92</A></SUP> and the
+multibyte functions. LC_MONETARY affects the monetary formatting
+information returned by the localeconv function. LC_NUMERIC affects
+the decimal-point character for the formatted input/output functions
+and the string conversion functions, as well as the non-monetary
+formatting information returned by the localeconv function. LC_TIME
+affects the behavior of the strftime function.
+</FONT></P><P>
+<FONT size="-1"> A value of "C" for locale specifies the minimal environment for C
+translation; a value of "" for locale specifies the implementation-defined
+native environment. Other implementation-defined strings may be passed
+as the second argument to setlocale .
+</FONT></P><P>
+<FONT size="-1"> At program startup, the equivalent of
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> setlocale(LC_ALL, "C");
+</FONT></P></PRE><P>
+<FONT size="-1">is executed.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+setlocale function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If a pointer to a string is given for locale and the selection can
+be honored, the setlocale function returns the string associated with
+the specified category for the new locale. If the selection cannot be
+honored, the setlocale function returns a null pointer and the
+program's locale is not changed.
+</FONT></P><P>
+<FONT size="-1"> A null pointer for locale causes the setlocale function to return
+the string associated with the category for the program's current
+locale; the program's locale is not changed.
+</FONT></P><P>
+<FONT size="-1"> The string returned by the setlocale function is such that a
+subsequent call with that string and its associated category will
+restore that part of the program's locale. The string returned shall
+not be modified by the program, but may be overwritten by a subsequent
+call to the setlocale function.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ formatted input/output functions (<A href="
+ #4.9.6">4.9.6</A>), the
+multibyte character functions (<A href="
+ #4.10.7">4.10.7</A>), the multibyte string
+functions (<A href="
+ #4.10.8">4.10.8</A>), string conversion functions (<A href="
+ #4.10.1">4.10.1</A>), the
+strcoll function (<A href="
+ #4.11.4.3">4.11.4.3</A>), the strftime function (<A href="
+ #4.12.3.5">4.12.3.5</A>), the
+strxfrm function (<A href="
+ #4.11.4.5">4.11.4.5</A>).
+</FONT></P><H4><A name="4.4.2">4.4.2 Numeric formatting convention inquiry</A></H4>
+<H5><A name="4.4.2.1">4.4.2.1 The localeconv function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <locale.h>
+ struct lconv *localeconv(void);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The localeconv function sets the components of an object with type
+struct lconv with values appropriate for the formatting of numeric
+quantities (monetary and otherwise) according to the rules of the
+current locale.
+</FONT></P><P>
+<FONT size="-1"> The members of the structure with type char * are strings, any of
+which (except decimal_point ) can point to , to indicate that the
+value is not available in the current locale or is of zero length.
+The members with type char are nonnegative numbers, any of which can
+be CHAR_MAX to indicate that the value is not available in the current
+locale. The members include the following: The decimal-point
+character used to format non-monetary quantities. The character used
+to separate groups of digits to the left of the decimal-point
+character in formatted non-monetary quantities. A string whose
+elements indicate the size of each group of digits in formatted
+non-monetary quantities. The international currency symbol applicable
+to the current locale. The first three characters contain the
+alphabetic international currency symbol in accordance with those
+specified in ISO 4217 Codes for the Representation of Currency and
+Funds .The fourth character (immediately preceding the null character)
+is the character used to separate the international currency symbol
+from the monetary quantity. The local currency symbol applicable to
+the current locale. The decimal-point used to format monetary
+quantities. The separator for groups of digits to the left of the
+decimal-point in formatted monetary quantities. A string whose
+elements indicate the size of each group of digits in formatted
+monetary quantities. The string used to indicate a nonnegative-valued
+formatted monetary quantity. The string used to indicate a
+negative-valued formatted monetary quantity. The number of fractional
+digits (those to the right of the decimal-point) to be displayed in a
+internationally formatted monetary quantity. The number of fractional
+digits (those to the right of the decimal-point) to be displayed in a
+formatted monetary quantity. Set to 1 or 0 if the currency_symbol
+respectively precedes or succeeds the value for a nonnegative
+formatted monetary quantity. Set to 1 or 0 if the currency_symbol
+respectively is or is not separated by a space from the value for a
+nonnegative formatted monetary quantity. Set to 1 or 0 if the
+currency_symbol respectively precedes or succeeds the value for a
+negative formatted monetary quantity. Set to 1 or 0 if the
+currency_symbol respectively is or is not separated by a space from
+the value for a negative formatted monetary quantity. Set to a value
+indicating the positioning of the positive_sign for a nonnegative
+formatted monetary quantity. Set to a value indicating the
+positioning of the negative_sign for a negative formatted monetary
+quantity.
+</FONT></P><P>
+<FONT size="-1"> The elements of grouping and mon_grouping are interpreted according
+to the following: No further grouping is to be performed. The
+previous element is to be repeatedly used for the remainder of the
+digits. The value is the number of digits that comprise the current
+group. The next element is examined to determine the size of the next
+group of digits to the left of the current group.
+</FONT></P><P>
+<FONT size="-1"> The value of p_sign_posn and n_sign_posn is interpreted according
+to the following: Parentheses surround the quantity and
+currency_symbol. The sign string precedes the quantity and
+currency_symbol. The sign string succeeds the quantity and
+currency_symbol. The sign string immediately precedes the
+currency_symbol. The sign string immediately succeeds the
+currency_symbol.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+localeconv function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The localeconv function returns a pointer to the filled-in object.
+The structure pointed to by the return value shall not be modified by
+the program, but may be overwritten by a subsequent call to the
+localeconv function. In addition, calls to the setlocale function
+with categories LC_ALL , LC_MONETARY , or LC_NUMERIC may overwrite the
+contents of the structure.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The following table illustrates the rules used by four countries to
+format monetary quantities.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> Country Positive format Negative format International format
+
+ Italy L.1.234 -L.1.234 ITL.1.234
+ Netherlands F 1.234,56 F -1.234,56 NLG 1.234,56
+ Norway kr1.234,56 kr1.234,56- NOK 1.234,56
+ Switzerland SFrs.1,234.56 SFrs.1,234.56C CHF 1,234.56
+</FONT></P></PRE><P>
+<FONT size="-1"> For these four countries, the respective values for the monetary
+members of the structure returned by localeconv are:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> Italy Netherlands Norway Switzerland
+
+ int_curr_symbol "ITL." "NLG " "NOK " "CHF "
+ currency_symbol "L." "F" "kr" "SFrs."
+ mon_decimal_point "" "," "," "."
+ mon_thousands_sep "." "." "." ","
+ mon_grouping "\3" "\3" "\3" "\3"
+ positive_sign "" "" "" ""
+ negative_sign "-" "-" "-" "C"
+ int_frac_digits 0 2 2 2
+ frac_digits 0 2 2 2
+ p_cs_precedes 1 1 1 1
+ p_sep_by_space 0 1 0 0
+ n_cs_precedes 1 1 1 1
+ n_sep_by_space 0 1 0 0
+ p_sign_posn 1 1 1 1
+ n_sign_posn 1 4 2 2
+</FONT></P></PRE></P><H3><A name="4.5">4.5 MATHEMATICS <math.h></A></H3>
+<P>
+<FONT size="-1"> The header <math.h> declares several mathematical functions and
+defines one macro. The functions take double-precision arguments and
+return double-precision values.<SUP><A href="
+ #93">93</A></SUP> Integer arithmetic functions and
+conversion functions are discussed later.
+</FONT></P><P>
+<FONT size="-1"> The macro defined is
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> HUGE_VAL
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to a positive double expression, not necessarily
+representable as a float .
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ integer arithmetic functions (<A href="
+ #4.10.6">4.10.6</A>), the atof
+function (<A href="
+ #4.10.1.1">4.10.1.1</A>), the strtod function (<A href="
+ #4.10.1.4">4.10.1.4</A>).
+</FONT></P><H4><A name="4.5.1">4.5.1 Treatment of error conditions</A></H4>
+<P>
+<FONT size="-1"> The behavior of each of these functions is defined for all
+representable values of its input arguments. Each function shall
+execute as if it were a single operation, without generating any
+externally visible exceptions.
+</FONT></P><P>
+<FONT size="-1"> For all functions, a domain error occurs if an input argument is
+outside the domain over which the mathematical function is defined.
+The description of each function lists any required domain errors; an
+implementation may define additional domain errors, provided that such
+errors are consistent with the mathematical definition of the
+function.<SUP><A href="
+ #94">94</A></SUP> On a domain error, the function returns an
+implementation-defined value; the value of the macro EDOM is stored in
+errno .
+</FONT></P><P>
+<FONT size="-1"> Similarly, a range error occurs if the result of the function
+cannot be represented as a double value. If the result overflows (the
+magnitude of the result is so large that it cannot be represented in
+an object of the specified type), the function returns the value of
+the macro HUGE_VAL , with the same sign as the correct value of the
+function; the value of the macro ERANGE is stored in errno . If the
+result underflows (the magnitude of the result is so small that it
+cannot be represented in an object of the specified type), the
+function returns zero; whether the integer expression errno acquires
+the value of the macro ERANGE is implementation-defined.
+</FONT></P><H4><A name="4.5.2">4.5.2 Trigonometric functions</A></H4>
+<H5><A name="4.5.2.1">4.5.2.1 The acos function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double acos(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The acos function computes the principal value of the arc cosine of x.
+A domain error occurs for arguments not in the range [-1, +1].
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The acos function returns the arc cosine in the range [0, PI] radians.
+</FONT></P></P><H5><A name="4.5.2.2">4.5.2.2 The asin function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double asin(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The asin function computes the principal value of the arc sine of x.
+A domain error occurs for arguments not in the range [-1, +1].
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The asin function returns the arc sine in the range [-PI/2, +PI/2]
+radians.
+</FONT></P></P><H5><A name="4.5.2.3">4.5.2.3 The atan function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double atan(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The atan function computes the principal value of the arc tangent of x.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The atan function returns the arc tangent in the range [-PI/2, +PI/2]
+radians.
+</FONT></P></P><H5><A name="4.5.2.4">4.5.2.4 The atan2 function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double atan2(double y, double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The atan2 function computes the principal value of the arc tangent
+of y/x , using the signs of both arguments to determine the quadrant
+of the return value. A domain error may occur if both arguments are
+zero.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The atan2 function returns the arc tangent of y/x , in the range
+[-PI, +PI] radians.
+</FONT></P></P><H5><A name="4.5.2.5">4.5.2.5 The cos function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double cos(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The cos function computes the cosine of x (measured in radians). A
+large magnitude argument may yield a result with little or no
+significance.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The cos function returns the cosine value.
+</FONT></P></P><H5><A name="4.5.2.6">4.5.2.6 The sin function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double sin(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The sin function computes the sine of x (measured in radians). A
+large magnitude argument may yield a result with little or no
+significance.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The sin function returns the sine value.
+</FONT></P></P><H5><A name="4.5.2.7">4.5.2.7 The tan function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double tan(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The tan function returns the tangent of x (measured in radians). A large magnitude argument may yield a result with little or no significance.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The tan function returns the tangent value.
+</FONT></P></P><H4><A name="4.5.3">4.5.3 Hyperbolic functions</A></H4>
+<H5><A name="4.5.3.1">4.5.3.1 The cosh function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double cosh(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The cosh function computes the hyperbolic cosine of x. A range
+error occurs if the magnitude of x is too large.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The cosh function returns the hyperbolic cosine value.
+</FONT></P></P><H5><A name="4.5.3.2">4.5.3.2 The sinh function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double sinh(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The sinh function computes the hyperbolic sine of x . A range error occurs if the magnitude of x is too large.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The sinh function returns the hyperbolic sine value.
+</FONT></P></P><H5><A name="4.5.3.3">4.5.3.3 The tanh function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double tanh(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The tanh function computes the hyperbolic tangent of x .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The tanh function returns the hyperbolic tangent value.
+</FONT></P></P><H4><A name="4.5.4">4.5.4 Exponential and logarithmic functions</A></H4>
+<H5><A name="4.5.4.1">4.5.4.1 The exp function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double exp(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The exp function computes the exponential function of x . A range
+error occurs if the magnitude of x is too large.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The exp function returns the exponential value.
+</FONT></P></P><H5><A name="4.5.4.2">4.5.4.2 The frexp function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double frexp(double value, int *exp);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The frexp function breaks a floating-point number into a normalized
+fraction and an integral power of 2. It stores the integer in the int
+object pointed to by exp .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The frexp function returns the value x , such that x is a double
+with magnitude in the interval [1/2, 1) or zero, and value equals x
+times 2 raised to the power *exp . If value is zero, both parts of
+the result are zero.
+</FONT></P></P><H5><A name="4.5.4.3">4.5.4.3 The ldexp function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double ldexp(double x, int exp);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The ldexp function multiplies a floating-point number by an
+integral power of 2. A range error may occur.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The ldexp function returns the value of x times 2 raised to the
+power exp .
+</FONT></P></P><H5><A name="4.5.4.4">4.5.4.4 The log function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double log(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The log function computes the natural logarithm of x. A domain
+error occurs if the argument is negative. A range error occurs if the
+argument is zero and the logarithm of zero cannot be represented.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The log function returns the natural logarithm.
+</FONT></P></P><H5><A name="4.5.4.5">4.5.4.5 The log10 function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double log10(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The log10 function computes the base-ten logarithm of x . A domain
+error occurs if the argument is negative. A range error occurs if the
+argument is zero and the logarithm of zero cannot be represented.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The log10 function returns the base-ten logarithm.
+</FONT></P></P><H5><A name="4.5.4.6">4.5.4.6 The modf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double modf(double value, double *iptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The modf function breaks the argument value into integral and
+fractional parts, each of which has the same sign as the argument. It
+stores the integral part as a double in the object pointed to by iptr.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The modf function returns the signed fractional part of value .
+</FONT></P></P><H4><A name="4.5.5">4.5.5 Power functions</A></H4>
+<H5><A name="4.5.5.1">4.5.5.1 The pow function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double pow(double x, double y);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The pow function computes x raised to the power y . A domain error
+occurs if x is negative and y is not an integer. A domain error
+occurs if the result cannot be represented when x is zero and y is
+less than or equal to zero. A range error may occur.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The pow function returns the value of x raised to the power y .
+</FONT></P></P><H5><A name="4.5.5.2">4.5.5.2 The sqrt function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double sqrt(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The sqrt function computes the nonnegative square root of x . A
+domain error occurs if the argument is negative.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The sqrt function returns the value of the square root.
+</FONT></P></P><H4><A name="4.5.6">4.5.6 Nearest integer, absolute value, and remainder functions</A></H4>
+<H5><A name="4.5.6.1">4.5.6.1 The ceil function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double ceil(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The ceil function computes the smallest integral value not less than x .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The ceil function returns the smallest integral value not less than
+x , expressed as a double.
+</FONT></P></P><H5><A name="4.5.6.2">4.5.6.2 The fabs function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double fabs(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fabs function computes the absolute value of a floating-point
+number x .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fabs function returns the absolute value of x.
+</FONT></P></P><H5><A name="4.5.6.3">4.5.6.3 The floor function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double floor(double x);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The floor function computes the largest integral value not greater
+than x .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The floor function returns the largest integral value not greater
+than x , expressed as a double.
+</FONT></P></P><H5><A name="4.5.6.4">4.5.6.4 The fmod function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ double fmod(double x, double y);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fmod function computes the floating-point remainder of x/y .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fmod function returns the value x i y , for some integer i such
+that, if y is nonzero, the result has the same sign as x and magnitude
+less than the magnitude of y . If y is zero, whether a domain error
+occurs or the fmod function returns zero is implementation-defined.
+</FONT></P></P>
+
+<H3><A name="4.6">4.6 NON-LOCAL JUMPS <setjmp.h></A></H3>
+<P>
+<FONT size="-1"> The header <setjmp.h> defines the macro setjmp , and declares one
+function and one type, for bypassing the normal function call and
+return discipline.<SUP><A href="
+ #95">95</A></SUP></FONT></P><P>
+<FONT size="-1"> The type declared is
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> jmp_buf
+</FONT></P></PRE><P>
+<FONT size="-1">which is an array type suitable for holding the information needed to
+restore a calling environment.
+</FONT></P><P>
+<FONT size="-1"> It is unspecified whether setjmp is a macro or an identifier
+declared with external linkage. If a macro definition is suppressed
+in order to access an actual function, or a program defines an
+external identifier with the name setjmp , the behavior is undefined.
+</FONT></P><H4><A name="4.6.1">4.6.1 Save calling environment</A></H4>
+<H5><A name="4.6.1.1">4.6.1.1 The setjmp macro</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <setjmp.h>
+ int setjmp(jmp_buf env);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The setjmp macro saves its calling environment in its jmp_buf
+argument for later use by the longjmp function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If the return is from a direct invocation, the setjmp macro returns
+the value zero. If the return is from a call to the longjmp function,
+the setjmp macro returns a nonzero value.
+</FONT></P><P>
+<FONT size="-1">"Environmental constraint"
+</FONT></P><P>
+<FONT size="-1"> An invocation of the setjmp macro shall appear only in one of the
+following contexts:
+</FONT></P><P>
+<FONT size="-1"> * the entire controlling expression of a selection or iteration statement;
+</FONT></P><P>
+<FONT size="-1"> * one operand of a relational or equality operator with the other
+ operand an integral constant expression, with the resulting expression
+ being the entire controlling expression of a selection or iteration
+ statement;
+</FONT></P><P>
+<FONT size="-1"> * the operand of a unary ! operator with the resulting expression
+ being the entire controlling expression of a selection or iteration
+ statement; or
+</FONT></P><P>
+<FONT size="-1"> * the entire expression of an expression statement (possibly cast to void).
+</FONT></P></P><H4><A name="4.6.2">4.6.2 Restore calling environment</A></H4>
+<H5><A name="4.6.2.1">4.6.2.1 The longjmp function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <setjmp.h>
+ void longjmp(jmp_buf env, int val);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The longjmp function restores the environment saved by the most
+recent invocation of the setjmp macro in the same invocation of the
+program, with the corresponding jmp_buf argument. If there has been
+no such invocation, or if the function containing the invocation of
+the setjmp macro has terminated execution<SUP><A href="
+ #96">96</A></SUP> in the interim, the
+behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> All accessible objects have values as of the time longjmp was
+called, except that the values of objects of automatic storage
+duration that do not have volatile type and have been changed between
+the setjmp invocation and longjmp call are indeterminate.
+</FONT></P><P>
+<FONT size="-1"> As it bypasses the usual function call and return mechanisms, the
+longjmp function shall execute correctly in contexts of interrupts,
+signals and any of their associated functions. However, if the
+longjmp function is invoked from a nested signal handler (that is,
+from a function invoked as a result of a signal raised during the
+handling of another signal), the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> After longjmp is completed, program execution continues as if the
+corresponding invocation of the setjmp macro had just returned the
+value specified by val . The longjmp function cannot cause the setjmp
+macro to return the value 0; if val is 0, the setjmp macro returns the
+value 1.
+</FONT></P></P><H3><A name="4.7">4.7 SIGNAL HANDLING <signal.h></A></H3>
+<P>
+<FONT size="-1"> The header <signal.h> declares a type and two functions and defines
+several macros, for handling various signals (conditions that may be
+reported during program execution).
+</FONT></P><P>
+<FONT size="-1"> The type defined is
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> sig_atomic_t
+</FONT></P></PRE><P>
+<FONT size="-1">which is the integral type of an object that can be accessed as an
+atomic entity, even in the presence of asynchronous interrupts.
+</FONT></P><P>
+<FONT size="-1"> The macros defined are
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> SIG_DFL
+ SIG_ERR
+ SIG_IGN
+</FONT></P></PRE><P>
+<FONT size="-1">which expand to distinct constant expressions that have type
+compatible with the second argument to and the return value of the
+signal function, and whose value compares unequal to the address of
+any declarable function; and the following, each of which expands to a
+positive integral constant expression that is the signal number
+corresponding to the specified condition:
+</FONT></P><P>
+<FONT size="-1">SIGABRT abnormal termination, such as is initiated by the abort function
+</FONT></P><P>
+<FONT size="-1">SIGFPE an erroneous arithmetic operation, such as zero divide or an
+ operation resulting in overflow
+</FONT></P><P>
+<FONT size="-1">SIGILL detection of an invalid function image, such as an illegal
+ instruction
+</FONT></P><P>
+<FONT size="-1">SIGINT receipt of an interactive attention signal
+</FONT></P><P>
+<FONT size="-1">SIGSEGV an invalid access to storage
+</FONT></P><P>
+<FONT size="-1">SIGTERM a termination request sent to the program
+</FONT></P><P>
+<FONT size="-1"> An implementation need not generate any of these signals, except as
+a result of explicit calls to the raise function. Additional signals
+and pointers to undeclarable functions, with macro definitions
+beginning, respectively, with the letters SIG and an upper-case letter
+or with SIG_ and an upper-case letter,<SUP><A href="
+ #97">97</A></SUP> may also be specified by
+the implementation. The complete set of signals, their semantics, and
+their default handling is implementation-defined; all signal values
+shall be positive.
+</FONT></P><H4><A name="4.7.1">4.7.1 Specify signal handling</A></H4>
+<H5><A name="4.7.1.1">4.7.1.1 The signal function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <signal.h>
+ void (*signal(int sig, void (*func)(int)))(int);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The signal function chooses one of three ways in which receipt of
+the signal number sig is to be subsequently handled. If the value of
+func is SIG_DFL , default handling for that signal will occur. If the
+value of func is SIG_IGN , the signal will be ignored. Otherwise,
+func shall point to a function to be called when that signal occurs.
+Such a function is called a signal handler .
+</FONT></P><P>
+<FONT size="-1"> When a signal occurs, if func points to a function, first the
+equivalent of signal(sig, SIG_DFL); is executed or an
+implementation-defined blocking of the signal is performed. (If the
+value of sig is SIGILL, whether the reset to SIG_DFL occurs is
+implementation-defined.) Next the equivalent of (*func)(sig); is
+executed. The function func may terminate by executing a return
+statement or by calling the abort , exit , or longjmp function. If
+func executes a return statement and the value of sig was SIGFPE or
+any other implementation-defined value corresponding to a
+computational exception, the behavior is undefined. Otherwise, the
+program will resume execution at the point it was interrupted.
+</FONT></P><P>
+<FONT size="-1"> If the signal occurs other than as the result of calling the abort
+or raise function, the behavior is undefined if the signal handler
+calls any function in the standard library other than the signal
+function itself or refers to any object with static storage duration
+other than by assigning a value to a static storage duration variable
+of type volatile sig_atomic_t . Furthermore, if such a call to the
+signal function results in a SIG_ERR return, the value of errno is
+indeterminate.
+</FONT></P><P>
+<FONT size="-1"> At program startup, the equivalent of
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> signal(sig, SIG_IGN);
+</FONT></P></PRE><P>
+<FONT size="-1">may be executed for some signals selected in an implementation-defined
+manner; the equivalent of
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> signal(sig, SIG_DFL);
+</FONT></P></PRE><P>
+<FONT size="-1">is executed for all other signals defined by the implementation.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+signal function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If the request can be honored, the signal function returns the
+value of func for the most recent call to signal for the specified
+signal sig . Otherwise, a value of SIG_ERR is returned and a positive
+value is stored in errno .
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the abort function (<A href="
+ #4.10.4.1">4.10.4.1</A>).
+</FONT></P><H4><A name="4.7.2">4.7.2 Send signal</A></H4>
+<H5><A name="4.7.2.1">4.7.2.1 The raise function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <signal.h>
+ int raise(int sig);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The raise function sends the signal sig to the executing program.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The raise function returns zero if successful, nonzero if unsuccessful.
+</FONT></P></P><H3><A name="4.8">4.8 VARIABLE ARGUMENTS <stdarg.h></A></H3>
+<P>
+<FONT size="-1"> The header <stdarg.h> declares a type and defines three macros, for
+advancing through a list of arguments whose number and types are not
+known to the called function when it is translated.
+</FONT></P><P>
+<FONT size="-1"> A function may be called with a variable number of arguments of
+varying types. As described in <A href="
+ #3.7.1">3.7.1</A>, its parameter list contains
+one or more parameters. The rightmost parameter plays a special role
+in the access mechanism, and will be designated parmN in this
+description.
+</FONT></P><P>
+<FONT size="-1"> The type declared is
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> va_list
+</FONT></P></PRE><P>
+<FONT size="-1">which is a type suitable for holding information needed by the macros
+va_start , va_arg , and va_end . If access to the varying arguments
+is desired, the called function shall declare an object (referred to
+as ap in this section) having type va_list . The object ap may be
+passed as an argument to another function; if that function invokes
+the va_arg macro with parameter ap , the value of ap in the calling
+function is indeterminate and shall be passed to the va_end macro
+prior to any further reference to ap .
+</FONT></P><H4><A name="4.8.1">4.8.1 Variable argument list access macros</A></H4>
+<P>
+<FONT size="-1"> The va_start and va_arg macros described in this section shall be
+implemented as macros, not as actual functions. It is unspecified
+whether va_end is a macro or an identifier declared with external
+linkage. If a macro definition is suppressed in order to access an
+actual function, or a program defines an external identifier with the
+name va_end , the behavior is undefined. The va_start and va_end
+macros shall be invoked in the function accepting a varying number of
+arguments, if access to the varying arguments is desired.
+</FONT></P><H5><A name="4.8.1.1">4.8.1.1 The va_start macro</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdarg.h>
+ void va_start(va_list ap, parmN);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The va_start macro shall be invoked before any access to the
+unnamed arguments.
+</FONT></P><P>
+<FONT size="-1"> The va_start macro initializes ap for subsequent use by va_arg and
+va_end .
+</FONT></P><P>
+<FONT size="-1"> The parameter parmN is the identifier of the rightmost parameter in
+the variable parameter list in the function definition (the one just
+before the , ... ). If the parameter parmN is declared with the
+register storage class, with a function or array type, or with a type
+that is not compatible with the type that results after application of
+the default argument promotions, the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The va_start macro returns no value.
+</FONT></P></P><H5><A name="4.8.1.2">4.8.1.2 The va_arg macro</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdarg.h>
+ type va_arg(va_list ap, type);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The va_arg macro expands to an expression that has the type and
+value of the next argument in the call. The parameter ap shall be the
+same as the va_list ap initialized by va_start . Each invocation of
+va_arg modifies ap so that the values of successive arguments are
+returned in turn. The parameter type is a type name specified such
+that the type of a pointer to an object that has the specified type
+can be obtained simply by postfixing a * to type . If there is no
+actual next argument, or if type is not compatible with the type of
+the actual next argument (as promoted according to the default
+argument promotions), the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The first invocation of the va_arg macro after that of the va_start
+macro returns the value of the argument after that specified by parmN.
+Successive invocations return the values of the remaining arguments
+in succession.
+</FONT></P></P><H5><A name="4.8.1.3">4.8.1.3 The va_end macro</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdarg.h>
+ void va_end(va_list ap);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The va_end macro facilitates a normal return from the function
+whose variable argument list was referred to by the expansion of
+va_start that initialized the va_list ap . The va_end macro may
+modify ap so that it is no longer usable (without an intervening
+invocation of va_start ). If there is no corresponding invocation of
+the va_start macro, or if the va_end macro is not invoked before the
+return, the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The va_end macro returns no value.
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> The function f1 gathers into an array a list of arguments that are
+pointers to strings (but not more than MAXARGS arguments), then passes
+the array as a single argument to function f2 . The number of
+pointers is specified by the first argument to f1 .
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdarg.h>
+ #define MAXARGS 31
+
+ void f1(int n_ptrs, ...)
+ {
+ va_list ap;
+ char *array[MAXARGS];
+ int ptr_no = 0;
+
+ if (n_ptrs > MAXARGS)
+ n_ptrs = MAXARGS;
+ va_start(ap, n_ptrs);
+ while (ptr_no < n_ptrs)
+ array[ptr_no++] = va_arg(ap, char *);
+ va_end(ap);
+ f2(n_ptrs, array);
+ }
+</FONT></P></PRE><P>
+<FONT size="-1">Each call to f1 shall have visible the definition of the function or a
+declaration such as
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> void f1(int, ...);
+</FONT></P></PRE></P><H3><A name="4.9">4.9 INPUT/OUTPUT <stdio.h></A></H3>
+<H4><A name="4.9.1">4.9.1 Introduction</A></H4>
+<P>
+<FONT size="-1"> The header <stdio.h> declares three types, several macros, and many
+functions for performing input and output.
+</FONT></P><P>
+<FONT size="-1"> The types declared are size_t (described in <A href="
+ #4.1.5">4.1.5</A>);
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> FILE
+</FONT></P></PRE><P>
+<FONT size="-1">which is an object type capable of recording all the information
+needed to control a stream, including its file position indicator, a
+pointer to its associated buffer, an error indicator that records
+whether a read/write error has occurred, and an end-of-file indicator
+that records whether the end of the file has been reached; and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> fpos_t
+</FONT></P></PRE><P>
+<FONT size="-1">which is an object type capable of recording all the information
+needed to specify uniquely every position within a file.
+</FONT></P><P>
+<FONT size="-1"> The macros are NULL (described in <A href="
+ #4.1.5">4.1.5</A>);
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> _IOFBF
+ _IOLBF
+ _IONBF
+</FONT></P></PRE><P>
+<FONT size="-1">which expand to distinct integral constant expressions, suitable for
+use as the third argument to the setvbuf function;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> BUFSIZ
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to an integral constant expression, which is the size of
+the buffer used by the setbuf function;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> EOF
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to a negative integral constant expression that is
+returned by several functions to indicate end-of-file ,that is, no
+more input from a stream;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> FOPEN_MAX
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to an integral constant expression that is the minimum
+number of files that the implementation guarantees can be open
+simultaneously;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> FILENAME_MAX
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to an integral constant expression that is the maximum
+length for a file name string that the implementation guarantees can
+be opened;<SUP><A href="
+ #98">98</A></SUP></FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> L_tmpnam
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to an integral constant expression that is the size of
+an array of char large enough to hold a temporary file name string
+generated by the tmpnam function;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> SEEK_CUR
+ SEEK_END
+ SEEK_SET
+</FONT></P></PRE><P>
+<FONT size="-1">which expand to distinct integral constant expressions, suitable for
+use as the third argument to the fseek function;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> TMP_MAX
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to an integral constant expression that is the minimum
+number of unique file names that shall be generated by the tmpnam
+function;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> stderr
+ stdin
+ stdout
+</FONT></P></PRE><P>
+<FONT size="-1">which are expressions of type ``pointer to FILE '' that point to the
+FILE objects associated, respectively, with the standard error, input,
+and output streams.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ files (<A href="
+ #4.9.3">4.9.3</A>), the fseek function (<A href="
+ #4.9.9.2">4.9.9.2</A>),
+streams (<A href="
+ #4.9.2">4.9.2</A>), the tmpnam function (<A href="
+ #4.9.4.4">4.9.4.4</A>).
+</FONT></P><H4><A name="4.9.2">4.9.2 Streams</A></H4>
+<P>
+<FONT size="-1"> Input and output, whether to or from physical devices such as
+terminals and tape drives, or whether to or from files supported on
+structured storage devices, are mapped into logical data streams,
+whose properties are more uniform than their various inputs and
+outputs. Two forms of mapping are supported, for text streams and for
+binary streams .<SUP><A href="
+ #99">99</A></SUP></FONT></P><P>
+<FONT size="-1"> A text stream is an ordered sequence of characters composed into
+lines , each line consisting of zero or more characters plus a
+terminating new-line character. Whether the last line requires a
+terminating new-line character is implementation-defined. Characters
+may have to be added, altered, or deleted on input and output to
+conform to differing conventions for representing text in the host
+environment. Thus, there need not be a one-to-one correspondence
+between the characters in a stream and those in the external
+representation. Data read in from a text stream will necessarily
+compare equal to the data that were earlier written out to that stream
+only if: the data consist only of printable characters and the control
+characters horizontal tab and new-line; no new-line character is
+immediately preceded by space characters; and the last character is a
+new-line character. Whether space characters that are written out
+immediately before a new-line character appear when read in is
+implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> A binary stream is an ordered sequence of characters that can
+transparently record internal data. Data read in from a binary stream
+shall compare equal to the data that were earlier written out to that
+stream, under the same implementation. Such a stream may, however,
+have an implementation-defined number of null characters appended.
+</FONT></P><P>
+<FONT size="-1">"Environmental limits"
+</FONT></P><P>
+<FONT size="-1"> An implementation shall support text files with lines containing at
+least 254 characters, including the terminating new-line character.
+The value of the macro BUFSIZ shall be at least 256.
+</FONT></P><H4><A name="4.9.3">4.9.3 Files</A></H4>
+<P>
+<FONT size="-1"> A stream is associated with an external file (which may be a
+physical device) by opening a file, which may involve creating a new
+file. Creating an existing file causes its former contents to be
+discarded, if necessary, so that it appears as if newly created. If a
+file can support positioning requests (such as a disk file, as opposed
+to a terminal), then a file position indicator<SUP><A href="
+ #100">100</A></SUP> associated with
+the stream is positioned at the start (character number zero) of the
+file, unless the file is opened with append mode in which case it is
+implementation-defined whether the file position indicator is
+positioned at the beginning or the end of the file. The file position
+indicator is maintained by subsequent reads, writes, and positioning
+requests, to facilitate an orderly progression through the file. All
+input takes place as if characters were read by successive calls to the
+fgetc function; all output takes place as if characters were written by
+successive calls to the fputc function.
+</FONT></P><P>
+<FONT size="-1"> Binary files are not truncated, except as defined in <A href="
+ #4.9.5.3">4.9.5.3</A>
+Whether a write on a text stream causes the associated file to be
+truncated beyond that point is implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> When a stream is unbuffered, characters are intended to appear
+from the source or at the destination as soon as possible. Otherwise
+characters may be accumulated and transmitted to or from the host
+environment as a block. When a stream is fully buffered, characters
+are intended to be transmitted to or from the host environment as a
+block when a buffer is filled. When a stream is line buffered,
+characters are intended to be transmitted to or from the host
+environment as a block when a new-line character is encountered.
+Furthermore, characters are intended to be transmitted as a block to
+the host environment when a buffer is filled, when input is requested
+on an unbuffered stream, or when input is requested on a line buffered
+stream that requires the transmission of characters from the host
+environment. Support for these characteristics is
+implementation-defined, and may be affected via the setbuf and setvbuf
+functions.
+</FONT></P><P>
+<FONT size="-1"> A file may be disassociated from its controlling stream by closing
+the file. Output streams are flushed (any unwritten buffer contents
+are transmitted to the host environment) before the stream is
+disassociated from the file. The value of a pointer to a FILE object
+is indeterminate after the associated file is closed (including the
+standard text streams). Whether a file of zero length (on which no
+characters have been written by an output stream) actually exists is
+implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> The file may be subsequently reopened, by the same or another
+program execution, and its contents reclaimed or modified (if it can
+be repositioned at its start). If the main function returns to its
+original caller, or if the exit function is called, all open files are
+closed (hence all output streams are flushed) before program
+termination. Other paths to program termination, such as calling the
+abort function, need not close all files properly.
+</FONT></P><P>
+<FONT size="-1"> The address of the FILE object used to control a stream may be
+significant; a copy of a FILE object may not necessarily serve in
+place of the original.
+</FONT></P><P>
+<FONT size="-1"> At program startup, three text streams are predefined and need not
+be opened explicitly --- standard input (for reading conventional
+input), standard output (for writing conventional output), and
+standard error (for writing diagnostic output). When opened, the
+standard error stream is not fully buffered; the standard input and
+standard output streams are fully buffered if and only if the stream
+can be determined not to refer to an interactive device.
+</FONT></P><P>
+<FONT size="-1"> Functions that open additional (nontemporary) files require a file
+name, which is a string. The rules for composing valid file names are
+implementation-defined. Whether the same file can be simultaneously
+open multiple times is also implementation-defined.
+</FONT></P><P>
+<FONT size="-1">"Environmental limits"
+</FONT></P><P>
+<FONT size="-1"> The value of the macro FOPEN_MAX shall be at least eight, including
+the three standard text streams.
+</FONT></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the exit function (<A href="
+ #4.10.4.3">4.10.4.3</A>), the fgetc function
+(<A href="
+ #4.9.7.1">4.9.7.1</A>), the fopen function (<A href="
+ #4.9.5.3">4.9.5.3</A>), the fputc function
+(<A href="
+ #4.9.7.3">4.9.7.3</A>), the setbuf function (<A href="
+ #4.9.5.5">4.9.5.5</A>), the setvbuf function
+(<A href="
+ #4.9.5.6">4.9.5.6</A>).
+</FONT></P><H4><A name="4.9.4">4.9.4 Operations on files</A></H4>
+<H5><A name="4.9.4.1">4.9.4.1 The remove function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int remove(const char *filename);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The remove function causes the file whose name is the string
+pointed to by filename to be no longer accessible by that name. A
+subsequent attempt to open that file using that name will fail, unless
+it is created anew. If the file is open, the behavior of the remove
+function is implementation-defined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The remove function returns zero if the operation succeeds, nonzero
+if it fails.
+</FONT></P></P><H5><A name="4.9.4.2">4.9.4.2 The rename function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int rename(const char *old, const char *new);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The rename function causes the file whose name is the string
+pointed to by old to be henceforth known by the name given by the
+string pointed to by new . The file named old is effectively removed.
+If a file named by the string pointed to by new exists prior to the
+call to the rename function, the behavior is implementation-defined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The rename function returns zero if the operation succeeds, nonzero
+if it fails,<SUP><A href="
+ #101">101</A></SUP> in which case if the file existed previously it is
+still known by its original name.
+</FONT></P></P><H5><A name="4.9.4.3">4.9.4.3 The tmpfile function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ FILE *tmpfile(void);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The tmpfile function creates a temporary binary file that will
+automatically be removed when it is closed or at program termination.
+If the program terminates abnormally, whether an open temporary file
+is removed is implementation-defined. The file is opened for update
+with wb+ mode.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The tmpfile function returns a pointer to the stream of the file
+that it created. If the file cannot be created, the tmpfile function
+returns a null pointer.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the fopen function (<A href="
+ #4.9.5.3">4.9.5.3</A>).
+</FONT></P><H5><A name="4.9.4.4">4.9.4.4 The tmpnam function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ char *tmpnam(char *s);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The tmpnam function generates a string that is a valid file name
+and that is not the same as the name of an existing file.<SUP><A href="
+ #102">102</A></SUP></FONT></P><P>
+<FONT size="-1"> The tmpnam function generates a different string each time it is
+called, up to TMP_MAX times. If it is called more than TMP_MAX times,
+the behavior is implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+tmpnam function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If the argument is a null pointer, the tmpnam function leaves its
+result in an internal static object and returns a pointer to that
+object. Subsequent calls to the tmpnam function may modify the same
+object. If the argument is not a null pointer, it is assumed to point
+to an array of at least L_tmpnam char s; the tmpnam function writes
+its result in that array and returns the argument as its value.
+</FONT></P><P>
+<FONT size="-1">"Environmental limits"
+</FONT></P><P>
+<FONT size="-1"> The value of the macro TMP_MAX shall be at least 25.
+</FONT></P></P><H4><A name="4.9.5">4.9.5 File access functions</A></H4>
+<H5><A name="4.9.5.1">4.9.5.1 The fclose function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fclose(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fclose function causes the stream pointed to by stream to be
+flushed and the associated file to be closed. Any unwritten buffered
+data for the stream are delivered to the host environment to be
+written to the file; any unread buffered data are discarded. The
+stream is disassociated from the file. If the associated buffer was
+automatically allocated, it is deallocated.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fclose function returns zero if the stream was successfully
+closed, or EOF if any errors were detected.
+</FONT></P></P><H5><A name="4.9.5.2">4.9.5.2 The fflush function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fflush(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> If stream points to an output stream or an update stream in which
+the most recent operation was output, the fflush function causes any
+unwritten data for that stream to be delivered to the host environment
+to be written to the file; otherwise, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> If stream is a null pointer, the fflush function performs this
+flushing action on all streams for which the behavior is defined
+above.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fflush function returns EOF if a write error occurs, otherwise zero.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the ungetc function (<A href="
+ #4.9.7.11">4.9.7.11</A>).
+</FONT></P><H5><A name="4.9.5.3">4.9.5.3 The fopen function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ FILE *fopen(const char *filename, const char *mode);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fopen function opens the file whose name is the string pointed
+to by filename , and associates a stream with it.
+</FONT></P><P>
+<FONT size="-1"> The argument mode points to a string beginning with one of the
+following sequences:<SUP><A href="
+ #103">103</A></SUP></FONT></P><P>
+<FONT size="-1">"r" open text file for reading
+"w" truncate to zero length or create text file for writing
+"a" append; open or create text file for writing at end-of-file
+"rb" open binary file for reading
+"wb" truncate to zero length or create binary file for writing
+"ab" append; open or create binary file for writing at end-of-file
+"r+" open text file for update (reading and writing)
+"w+" truncate to zero length or create text file for update
+"a+" append; open or create text file for update, writing at
+ end-of-file
+"r+b" or "rb+" open binary file for update (reading and writing)
+"w+b" or "wb+" truncate to zero length or create binary file for update
+"a+b" or "ab+" append; open or create binary file for update, writing at
+ end-of-file
+</FONT></P><P>
+<FONT size="-1"> Opening a file with read mode ('r' as the first character in the
+mode argument) fails if the file does not exist or cannot be read.
+</FONT></P><P>
+<FONT size="-1"> Opening a file with append mode ('a' as the first character in the
+mode argument) causes all subsequent writes to the file to be forced
+to the then current end-of-file, regardless of intervening calls to
+the fseek function. In some implementations, opening a binary file
+with append mode ('b' as the second or third character in the mode
+argument) may initially position the file position indicator for the
+stream beyond the last data written, because of null character
+padding.
+</FONT></P><P>
+<FONT size="-1"> When a file is opened with update mode ('+' as the second or third
+character in the mode argument), both input and output may be
+performed on the associated stream. However, output may not be
+directly followed by input without an intervening call to the fflush
+function or to a file positioning function ( fseek , fsetpos , or
+rewind ), and input may not be directly followed by output without an
+intervening call to a file positioning function, unless the input
+operation encounters end-of-file. Opening a file with update mode may
+open or create a binary stream in some implementations.
+</FONT></P><P>
+<FONT size="-1"> When opened, a stream is fully buffered if and only if it can be
+determined not to refer to an interactive device. The error and
+end-of-file indicators for the stream are cleared.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fopen function returns a pointer to the object controlling the
+stream. If the open operation fails, fopen returns a null pointer.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ file positioning functions (<A href="
+ #4.9.9">4.9.9</A>).
+</FONT></P><H5><A name="4.9.5.4">4.9.5.4 The freopen function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ FILE *freopen(const char *filename, const char *mode,
+ FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The freopen function opens the file whose name is the string
+pointed to by filename and associates the stream pointed to by stream
+with it. The mode argument is used just as in the fopen
+function.<SUP><A href="
+ #104">104</A></SUP></FONT></P><P>
+<FONT size="-1"> The freopen function first attempts to close any file that is
+associated with the specified stream. Failure to close the file
+successfully is ignored. The error and end-of-file indicators for the
+stream are cleared.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The freopen function returns a null pointer if the open operation
+fails. Otherwise, freopen returns the value of stream .
+</FONT></P></P><H5><A name="4.9.5.5">4.9.5.5 The setbuf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ void setbuf(FILE *stream, char *buf);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> Except that it returns no value, the setbuf function is equivalent
+to the setvbuf function invoked with the values _IOFBF for mode and
+BUFSIZ for size , or (if buf is a null pointer), with the value _IONBF
+for mode .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The setbuf function returns no value.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the setvbuf function (<A href="
+ #4.9.5.6">4.9.5.6</A>).
+</FONT></P><H5><A name="4.9.5.6">4.9.5.6 The setvbuf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int setvbuf(FILE *stream, char *buf, int mode, size_t size);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The setvbuf function may be used after the stream pointed to by
+stream has been associated with an open file but before any other
+operation is performed on the stream. The argument mode determines
+how stream will be buffered, as follows: _IOFBF causes input/output to
+be fully buffered; _IOLBF causes output to be line buffered; _IONBF
+causes input/output to be unbuffered. If buf is not a null pointer,
+the array it points to may be used instead of a buffer allocated by
+the setvbuf function.<SUP><A href="
+ #105">105</A></SUP> The argument size specifies the size of the
+array. The contents of the array at any time are indeterminate.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The setvbuf function returns zero on success, or nonzero if an
+invalid value is given for mode or if the request cannot be honored.
+</FONT></P></P>
+
+<H4><A name="4.9.6">4.9.6 Formatted input/output functions</A></H4>
+<H5><A name="4.9.6.1">4.9.6.1 The fprintf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fprintf(FILE *stream, const char *format, ...);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fprintf function writes output to the stream pointed to by
+stream , under control of the string pointed to by format that
+specifies how subsequent arguments are converted for output. If there
+are insufficient arguments for the format, the behavior is undefined.
+If the format is exhausted while arguments remain, the excess
+arguments are evaluated (as always) but are otherwise ignored. The
+fprintf function returns when the end of the format string is
+encountered.
+</FONT></P><P>
+<FONT size="-1"> The format shall be a multibyte character sequence, beginning and
+ending in its initial shift state. The format is composed of zero or
+more directives: ordinary multibyte characters (not % ), which are
+copied unchanged to the output stream; and conversion specifications,
+each of which results in fetching zero or more subsequent arguments.
+Each conversion specification is introduced by the character % .
+After the % , the following appear in sequence:
+</FONT></P><P>
+<FONT size="-1"> * Zero or more flags that modify the meaning of the conversion
+ specification.
+</FONT></P><P>
+<FONT size="-1"> * An optional decimal integer specifying a minimum field width .<SUP><A href="
+ #106">106</A></SUP>
+ If the converted value has fewer characters than the field width, it
+ will be padded with spaces on the left (or right, if the left
+ adjustment flag, described later, has been given) to the field width.
+</FONT></P><P>
+<FONT size="-1"> * An optional precision that gives the minimum number of digits to
+ appear for the d , i , o , u , x , and X conversions, the number of
+ digits to appear after the decimal-point character for e , E , and f
+ conversions, the maximum number of significant digits for the g and G
+ conversions, or the maximum number of characters to be written from a
+ string in s conversion. The precision takes the form of a period (.)
+ followed by an optional decimal integer; if the integer is
+ omitted, it is treated as zero.
+</FONT></P><P>
+<FONT size="-1"> * An optional h specifying that a following d , i , o , u , x , or X
+ conversion specifier applies to a short int or unsigned short int
+ argument (the argument will have been promoted according to the
+ integral promotions, and its value shall be converted to short int or
+ unsigned short int before printing); an optional h specifying that a
+ following n conversion specifier applies to a pointer to a short int
+ argument; an optional l (ell) specifying that a following d , i , o ,
+ u , x , or X conversion specifier applies to a long int or unsigned
+ long int argument; an optional l specifying that a following n
+ conversion specifier applies to a pointer to a long int argument; or
+ an optional L specifying that a following e , E , f , g , or G
+ conversion specifier applies to a long double argument. If an h , l ,
+ or L appears with any other conversion specifier, the behavior is
+ undefined.
+</FONT></P><P>
+<FONT size="-1"> * A character that specifies the type of conversion to be applied.
+</FONT></P><P>
+<FONT size="-1"> A field width or precision, or both, may be indicated by an
+asterisk * instead of a digit string. In this case, an int argument
+supplies the field width or precision. The arguments specifying field
+width or precision, or both, shall appear (in that order) before the
+argument (if any) to be converted. A negative field width argument is
+taken as a - flag followed by a positive field width. A negative
+precision argument is taken as if it were missing.
+</FONT></P><P>
+<FONT size="-1"> The flag characters and their meanings are
+</FONT></P><P>
+<FONT size="-1">- The result of the conversion will be left-justified within the field.
+</FONT></P><P>
+<FONT size="-1">+ The result of a signed conversion will always begin with a plus or
+ minus sign.
+</FONT></P><P>
+<FONT size="-1">space If the first character of a signed conversion is not a sign,
+ or if a signed conversion results in no characters, a space will be
+ prepended to the result. If the space and + flags both appear, the
+ space flag will be ignored.
+</FONT></P><P>
+<FONT size="-1"># The result is to be converted to an ``alternate form.'' For
+ o conversion, it increases the precision to force the first digit of
+ the result to be a zero. For x (or X ) conversion, a nonzero result
+ will have 0x (or 0X ) prepended to it. For e , E , f , g , and G
+ conversions, the result will always contain a decimal-point character,
+ even if no digits follow it (normally, a decimal-point character
+ appears in the result of these conversions only if a digit follows
+ it). For g and G conversions, trailing zeros will not be removed from
+ the result. For other conversions, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1">0 For d, i, o, u, x, X, e, E, f, g and G conversions, leading zeros
+ (following any indication of sign or base) are used to pad to the
+ field width; no space padding is performed. If the 0 and - flags
+ both appear, the 0 flag will be ignored. For d, i, o, u, x and X
+ conversions, if a precision is specified, the 0 flag will be
+ ignored. For other conversions, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> The conversion specifiers and their meanings are
+</FONT></P><P>
+<FONT size="-1">d, i, o, u, x, X The int argument is converted to signed decimal ( d
+ or i ), unsigned octal ( o ), unsigned decimal ( u ), or unsigned
+ hexadecimal notation ( x or X ); the letters abcdef are used for x
+ conversion and the letters ABCDEF for X conversion. The precision
+ specifies the minimum number of digits to appear; if the value being
+ converted can be represented in fewer digits, it will be expanded with
+ leading zeros. The default precision is 1. The result of converting
+ a zero value with an explicit precision of zero is no characters.
+</FONT></P><P>
+<FONT size="-1">f The double argument is converted to decimal notation in the style
+ [-]ddd.ddd , where the number of digits after the decimal-point
+ character is equal to the precision specification. If the precision
+ is missing, it is taken as 6; if the precision is explicitly zero, no
+ decimal-point character appears. If a decimal-point character
+ appears, at least one digit appears before it. The value is rounded
+ to the appropriate number of digits.
+</FONT></P><P>
+<FONT size="-1">e, E The double argument is converted in the style [-]d.ddde+- dd ,
+ where there is one digit before the decimal-point character (which is
+ nonzero if the argument is nonzero) and the number of digits after it
+ is equal to the precision; if the precision is missing, it is taken as
+ 6; if the precision is zero, no decimal-point character appears. The
+ value is rounded to the appropriate number of digits. The E
+ conversion specifier will produce a number with E instead of e
+ introducing the exponent. The exponent always contains at least two
+ digits. If the value is zero, the exponent is zero.
+</FONT></P><P>
+<FONT size="-1">g, G The double argument is converted in style f or e (or in style E
+ in the case of a G conversion specifier), with the precision
+ specifying the number of significant digits. If an explicit precision
+ is zero, it is taken as 1. The style used depends on the value
+ converted; style e will be used only if the exponent resulting from
+ such a conversion is less than -4 or greater than or equal to the
+ precision. Trailing zeros are removed from the fractional portion of
+ the result; a decimal-point character appears only if it is followed
+ by a digit.
+</FONT></P><P>
+<FONT size="-1">c The int argument is converted to an unsigned char , and the resulting
+ character is written.
+</FONT></P><P>
+<FONT size="-1">s The argument shall be a pointer to an array of character type.<SUP><A href="
+ #107">107</A></SUP>
+ Characters from the array are written up to (but not including) a
+ terminating null character; if the precision is specified, no more
+ than that many characters are written. If the precision is not
+ specified or is greater than the size of the array, the array shall
+ contain a null character.
+</FONT></P><P>
+<FONT size="-1">p The argument shall be a pointer to void . The value of the pointer
+ is converted to a sequence of printable characters, in an
+ implementation-defined manner.
+</FONT></P><P>
+<FONT size="-1">n The argument shall be a pointer to an integer into which is written
+ the number of characters written to the output stream so far by this
+ call to fprintf . No argument is converted.
+</FONT></P><P>
+<FONT size="-1">% A % is written. No argument is converted. The complete conversion
+ specification shall be %% .
+</FONT></P><P>
+<FONT size="-1"> If a conversion specification is invalid, the behavior is
+undefined.<SUP><A href="
+ #108">108</A></SUP></FONT></P><P>
+<FONT size="-1"> If any argument is, or points to, a union or an aggregate (except
+for an array of character type using %s conversion, or a pointer cast
+to be a pointer to void using %p conversion), the behavior is
+undefined.
+</FONT></P><P>
+<FONT size="-1"> In no case does a nonexistent or small field width cause truncation
+of a field; if the result of a conversion is wider than the field
+width, the field is expanded to contain the conversion result.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fprintf function returns the number of characters transmitted,
+or a negative value if an output error occurred.
+</FONT></P><P>
+<FONT size="-1">"Environmental limit"
+</FONT></P><P>
+<FONT size="-1"> The minimum value for the maximum number of characters produced by
+any single conversion shall be 509.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> To print a date and time in the form ``Sunday, July 3, 10:02,''
+where weekday and month are pointers to strings:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ fprintf(stdout, "%s, %s %d, %.2d:%.2d\n",
+ weekday, month, day, hour, min);
+</FONT></P></PRE><P>
+<FONT size="-1">To print PI to five decimal places:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <math.h>
+ #include <stdio.h>
+ fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0));
+</FONT></P></PRE></P><H5><A name="4.9.6.2">4.9.6.2 The fscanf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fscanf(FILE *stream, const char *format, ...);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fscanf function reads input from the stream pointed to by
+stream , under control of the string pointed to by format that
+specifies the admissible input sequences and how they are to be
+converted for assignment, using subsequent arguments as pointers to
+the objects to receive the converted input. If there are insufficient
+arguments for the format, the behavior is undefined. If the format is
+exhausted while arguments remain, the excess arguments are evaluated
+(as always) but are otherwise ignored.
+</FONT></P><P>
+<FONT size="-1"> The format shall be a multibyte character sequence, beginning and
+ending in its initial shift state. The format is composed of zero or
+more directives: one or more white-space characters; an ordinary
+multibyte character (not % ); or a conversion specification. Each
+conversion specification is introduced by the character % . After the %,
+the following appear in sequence:
+</FONT></P><P>
+<FONT size="-1"> * An optional assignment-suppressing character * .
+</FONT></P><P>
+<FONT size="-1"> * An optional decimal integer that specifies the maximum field width.
+</FONT></P><P>
+<FONT size="-1"> * An optional h , l (ell) or L indicating the size of the receiving
+ object. The conversion specifiers d , i , and n shall be preceded by
+ h if the corresponding argument is a pointer to short int rather than
+ a pointer to int , or by l if it is a pointer to long int .
+ Similarly, the conversion specifiers o , u , and x shall be preceded
+ by h if the corresponding argument is a pointer to unsigned short int
+ rather than a pointer to unsigned int , or by l if it is a pointer to
+ unsigned long int . Finally, the conversion specifiers e , f , and g
+ shall be preceded by l if the corresponding argument is a pointer to
+ double rather than a pointer to float , or by L if it is a pointer to
+ long double . If an h , l , or L appears with any other conversion
+ specifier, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> * A character that specifies the type of conversion to be applied.
+The valid conversion specifiers are described below.
+</FONT></P><P>
+<FONT size="-1"> The fscanf function executes each directive of the format in turn.
+If a directive fails, as detailed below, the fscanf function returns.
+Failures are described as input failures (due to the unavailability of
+input characters), or matching failures (due to inappropriate input).
+</FONT></P><P>
+<FONT size="-1"> A directive composed of white space is executed by reading input up
+to the first non-white-space character (which remains unread), or
+until no more characters can be read.
+</FONT></P><P>
+<FONT size="-1"> A directive that is an ordinary multibyte character is executed by
+reading the next characters of the stream. If one of the characters
+differs from one comprising the directive, the directive fails, and
+the differing and subsequent characters remain unread.
+</FONT></P><P>
+<FONT size="-1"> A directive that is a conversion specification defines a set of
+matching input sequences, as described below for each specifier. A
+conversion specification is executed in the following steps:
+</FONT></P><P>
+<FONT size="-1"> Input white-space characters (as specified by the isspace function)
+are skipped, unless the specification includes a [ , c , or n
+specifier.
+</FONT></P><P>
+<FONT size="-1"> An input item is read from the stream, unless the specification
+includes an n specifier. An input item is defined as the longest
+sequence of input characters (up to any specified maximum field width)
+which is an initial subsequence of a matching sequence. The first
+character, if any, after the input item remains unread. If the length
+of the input item is zero, the execution of the directive fails: this
+condition is a matching failure, unless an error prevented input from
+the stream, in which case it is an input failure.
+</FONT></P><P>
+<FONT size="-1"> Except in the case of a % specifier, the input item (or, in the
+case of a %n directive, the count of input characters) is converted to
+a type appropriate to the conversion specifier. If the input item is
+not a matching sequence, the execution of the directive fails: this
+condition is a matching failure. Unless assignment suppression was
+indicated by a * , the result of the conversion is placed in the
+object pointed to by the first argument following the format argument
+that has not already received a conversion result. If this object
+does not have an appropriate type, or if the result of the conversion
+cannot be represented in the space provided, the behavior is
+undefined.
+</FONT></P><P>
+<FONT size="-1"> The following conversion specifiers are valid:
+</FONT></P><P>
+<FONT size="-1">d Matches an optionally signed decimal integer, whose format is the
+ same as expected for the subject sequence of the strtol function with
+ the value 10 for the base argument. The corresponding argument shall
+ be a pointer to integer.
+</FONT></P><P>
+<FONT size="-1">i Matches an optionally signed integer, whose format is the same as
+ expected for the subject sequence of the strtol function with the
+ value 0 for the base argument. The corresponding argument shall be a
+ pointer to integer.
+</FONT></P><P>
+<FONT size="-1">o Matches an optionally signed octal integer, whose format is the same
+ as expected for the subject sequence of the strtoul function with the
+ value 8 for the base argument. The corresponding argument shall be a
+ pointer to unsigned integer.
+</FONT></P><P>
+<FONT size="-1">u Matches an optionally signed decimal integer, whose format is the same
+ as expected for the subject sequence of the strtoul function with the
+ value 10 for the base argument. The corresponding argument shall be a
+ pointer to unsigned integer.
+</FONT></P><P>
+<FONT size="-1">x Matches an optionally signed hexadecimal integer, whose format is the
+ same as expected for the subject sequence of the strtoul function with
+ the value 16 for the base argument. The corresponding argument shall
+ be a pointer to unsigned integer.
+</FONT></P><P>
+<FONT size="-1">e,f,g Matches an optionally signed floating-point number, whose format is
+ the same as expected for the subject string of the strtod function.
+ The corresponding argument shall be a pointer to floating.
+</FONT></P><P>
+<FONT size="-1">s Matches a sequence of non-white-space characters. The corresponding
+ argument shall be a pointer to the initial character of an array large
+ enough to accept the sequence and a terminating null character, which
+ will be added automatically.
+</FONT></P><P>
+<FONT size="-1">[ Matches a nonempty sequence of characters from a set of expected
+ characters (the scanset ). The corresponding argument shall be a
+ pointer to the initial character of an array large enough to accept
+ the sequence and a terminating null character, which will be added
+ automatically. The conversion specifier includes all subsequent
+ characters in the format string, up to and including the matching
+ right bracket ( ] ). The characters between the brackets (the
+ scanlist ) comprise the scanset, unless the character after the left
+ bracket is a circumflex ( ^ ), in which case the scanset contains all
+ characters that do not appear in the scanlist between the circumflex
+ and the right bracket. As a special case, if the conversion specifier
+ begins with [] or [^] , the right bracket character is in the scanlist
+ and the next right bracket character is the matching right bracket
+ that ends the specification. If a - character is in the scanlist and
+ is not the first, nor the second where the first character is a ^ ,
+ nor the last character, the behavior is implementation-defined.
+</FONT></P><P>
+<FONT size="-1">c Matches a sequence of characters of the number specified by the
+ field width (1 if no field width is present in the directive). The
+ corresponding argument shall be a pointer to the initial character of
+ an array large enough to accept the sequence. No null character is
+ added.
+</FONT></P><P>
+<FONT size="-1">p Matches an implementation-defined set of sequences, which should be
+ the same as the set of sequences that may be produced by the %p
+ conversion of the fprintf function. The corresponding argument shall
+ be a pointer to a pointer to void . The interpretation of the input
+ item is implementation-defined; however, for any input item other than
+ a value converted earlier during the same program execution, the
+ behavior of the %p conversion is undefined.
+</FONT></P><P>
+<FONT size="-1">n No input is consumed. The corresponding argument shall be a pointer
+ to integer into which is to be written the number of characters read
+ from the input stream so far by this call to the fscanf function.
+ Execution of a %n directive does not increment the assignment count
+ returned at the completion of execution of the fscanf function.
+</FONT></P><P>
+<FONT size="-1">% Matches a single % ; no conversion or assignment occurs. The complete
+ conversion specification shall be %% .
+</FONT></P><P>
+<FONT size="-1"> If a conversion specification is invalid, the behavior is
+undefined.<SUP><A href="
+ #110">110</A></SUP></FONT></P><P>
+<FONT size="-1"> The conversion specifiers E , G , and X are also valid and behave
+the same as, respectively, e , g , and x .
+</FONT></P><P>
+<FONT size="-1"> If end-of-file is encountered during input, conversion is
+terminated. If end-of-file occurs before any characters matching the
+current directive have been read (other than leading white space,
+where permitted), execution of the current directive terminates with
+an input failure; otherwise, unless execution of the current directive
+is terminated with a matching failure, execution of the following
+directive (if any) is terminated with an input failure.
+</FONT></P><P>
+<FONT size="-1"> If conversion terminates on a conflicting input character, the
+offending input character is left unread in the input stream.
+Trailing white space (including new-line characters) is left unread
+unless matched by a directive. The success of literal matches and
+suppressed assignments is not directly determinable other than via the
+%n directive.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fscanf function returns the value of the macro EOF if an input
+failure occurs before any conversion. Otherwise, the fscanf function
+returns the number of input items assigned, which can be fewer than
+provided for, or even zero, in the event of an early matching failure.
+</FONT></P></P><H6>Examples</H6>
+<P>
+<P>
+<FONT size="-1"> The call:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int n, i; float x; char name[50];
+ n = fscanf(stdin, "%d%f%s", &i, &x, name);
+</FONT></P></PRE><P>
+<FONT size="-1">with the input line:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> 25 54.32E-1 thompson
+</FONT></P></PRE><P>
+<FONT size="-1">will assign to n the value 3, to i the value 25, to x the value 5.432,
+and name will contain thompson\0 . Or:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int i; float x; char name[50];
+ fscanf(stdin, "%2d%f%*d %[0123456789]", &i, &x, name);
+</FONT></P></PRE><P>
+<FONT size="-1">with input:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> 56789 0123 56a72
+</FONT></P></PRE><P>
+<FONT size="-1">will assign to i the value 56 and to x the value 789.0, will skip
+0123, and name will contain 56\0 . The next character read from the
+input stream will be a .
+</FONT></P><P>
+<FONT size="-1"> To accept repeatedly from stdin a quantity, a unit of measure and
+an item name:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int count; float quant; char units[21], item[21];
+ while (!feof(stdin) && !ferror(stdin)) {
+ count = fscanf(stdin, "%f%20s of %20s",
+ &quant, units, item);
+ fscanf(stdin,"%*[^\n]");
+ }
+</FONT></P></PRE><P>
+<FONT size="-1"> If the stdin stream contains the following lines:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> 2 quarts of oil
+ -12.8degrees Celsius
+ lots of luck
+ 10.0LBS of fertilizer
+ 100ergs of energy
+</FONT></P></PRE><P>
+<FONT size="-1">the execution of the above example will be equivalent to the following
+assignments:
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> quant = 2; strcpy(units, "quarts"); strcpy(item, "oil");
+ count = 3;
+ quant = -12.8; strcpy(units, "degrees");
+ count = 2; /* "C" fails to match "o" */
+ count = 0; /* "l" fails to match "%f" */
+ quant = 10.0; strcpy(units, "LBS"); strcpy(item, "fertilizer");
+ count = 3;
+ count = 0; /* "100e" fails to match "%f" */
+ count = EOF;
+</FONT></P></PRE></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the strtod function (<A href="
+ #4.10.1.4">4.10.1.4</A>), the strtol
+function (<A href="
+ #4.10.1.5">4.10.1.5</A>), the strtoul function (<A href="
+ #4.10.1.6">4.10.1.6</A>).
+</FONT></P><H5><A name="4.9.6.3">4.9.6.3 The printf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int printf(const char *format, ...);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The printf function is equivalent to fprintf with the argument
+stdout interposed before the arguments to printf .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The printf function returns the number of characters transmitted,
+or a negative value if an output error occurred.
+</FONT></P></P><H5><A name="4.9.6.4">4.9.6.4 The scanf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int scanf(const char *format, ...);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The scanf function is equivalent to fscanf with the argument stdin
+interposed before the arguments to scanf .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The scanf function returns the value of the macro EOF if an input
+failure occurs before any conversion. Otherwise, the scanf function
+returns the number of input items assigned, which can be fewer than
+provided for, or even zero, in the event of an early matching failure.
+</FONT></P></P><H5><A name="4.9.6.5">4.9.6.5 The sprintf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int sprintf(char *s, const char *format, ...);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The sprintf function is equivalent to fprintf , except that the
+argument s specifies an array into which the generated output is to be
+written, rather than to a stream. A null character is written at the
+end of the characters written; it is not counted as part of the
+returned sum. If copying takes place between objects that overlap,
+the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The sprintf function returns the number of characters written in
+the array, not counting the terminating null character.
+</FONT></P></P><H5><A name="4.9.6.6">4.9.6.6 The sscanf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int sscanf(const char *s, const char *format, ...);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The sscanf function is equivalent to fscanf , except that the
+argument s specifies a string from which the input is to be obtained,
+rather than from a stream. Reaching the end of the string is
+equivalent to encountering end-of-file for the fscanf function. If
+copying takes place between objects that overlap, the behavior is
+undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The sscanf function returns the value of the macro EOF if an input
+failure occurs before any conversion. Otherwise, the sscanf function
+returns the number of input items assigned, which can be fewer than
+provided for, or even zero, in the event of an early matching failure.
+</FONT></P></P><H5><A name="4.9.6.7">4.9.6.7 The vfprintf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdarg.h>
+ #include <stdio.h>
+ int vfprintf(FILE *stream, const char *format, va_list arg);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The vfprintf function is equivalent to fprintf , with the variable
+argument list replaced by arg , which has been initialized by the
+va_start macro (and possibly subsequent va_arg calls). The vfprintf
+function does not invoke the va_end macro.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The vfprintf function returns the number of characters transmitted,
+or a negative value if an output error occurred.
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> The following shows the use of the vfprintf function in a general
+error-reporting routine.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdarg.h>
+ #include <stdio.h>
+
+ void error(char *function_name, char *format, ...)
+ {
+ va_list args;
+
+ va_start(args, format);
+ /* print out name of function causing error */
+ fprintf(stderr, "ERROR in %s: ", function_name);
+ /* print out remainder of message */
+ vfprintf(stderr, format, args);
+ va_end(args);
+ }
+</FONT></P></PRE></P><H5><A name="4.9.6.8">4.9.6.8 The vprintf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdarg.h>
+ #include <stdio.h>
+ int vprintf(const char *format, va_list arg);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The vprintf function is equivalent to printf , with the variable
+argument list replaced by arg , which has been initialized by the
+va_start macro (and possibly subsequent va_arg calls). The vprintf
+function does not invoke the va_end macro.rN
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The vprintf function returns the number of characters transmitted,
+or a negative value if an output error occurred.
+</FONT></P></P><H5><A name="4.9.6.9">4.9.6.9 The vsprintf function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdarg.h>
+ #include <stdio.h>
+ int vsprintf(char *s, const char *format, va_list arg);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The vsprintf function is equivalent to sprintf , with the variable
+argument list replaced by arg , which has been initialized by the
+va_start macro (and possibly subsequent va_arg calls). The vsprintf
+function does not invoke the va_end macro.rN If copying takes place
+between objects that overlap, the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The vsprintf function returns the number of characters written in
+the array, not counting the terminating null character.
+</FONT></P></P><H4><A name="4.9.7">4.9.7 Character input/output functions</A></H4>
+<H5><A name="4.9.7.1">4.9.7.1 The fgetc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fgetc(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fgetc function obtains the next character (if present) as an
+unsigned char converted to an int , from the input stream pointed to
+by stream , and advances the associated file position indicator for
+the stream (if defined).
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fgetc function returns the next character from the input stream
+pointed to by stream . If the stream is at end-of-file, the
+end-of-file indicator for the stream is set and fgetc returns EOF .
+If a read error occurs, the error indicator for the stream is set and
+fgetc returns EOF .<SUP><A href="
+ #112">112</A></SUP></FONT></P></P><H5><A name="4.9.7.2">4.9.7.2 The fgets function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ char *fgets(char *s, int n, FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fgets function reads at most one less than the number of
+characters specified by n from the stream pointed to by stream into
+the array pointed to by s . No additional characters are read after a
+new-line character (which is retained) or after end-of-file. A null
+character is written immediately after the last character read into
+the array.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fgets function returns s if successful. If end-of-file is
+encountered and no characters have been read into the array, the
+contents of the array remain unchanged and a null pointer is returned.
+If a read error occurs during the operation, the array contents are
+indeterminate and a null pointer is returned.
+</FONT></P></P><H5><A name="4.9.7.3">4.9.7.3 The fputc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fputc(int c, FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fputc function writes the character specified by c (converted
+to an unsigned char ) to the output stream pointed to by stream , at
+the position indicated by the associated file position indicator for
+the stream (if defined), and advances the indicator appropriately. If
+the file cannot support positioning requests, or if the stream was
+opened with append mode, the character is appended to the output
+stream.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fputc function returns the character written. If a write error
+occurs, the error indicator for the stream is set and fputc returns EOF.
+</FONT></P></P><H5><A name="4.9.7.4">4.9.7.4 The fputs function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fputs(const char *s, FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fputs function writes the string pointed to by s to the stream
+pointed to by stream . The terminating null character is not written.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fputs function returns EOF if a write error occurs; otherwise
+it returns a nonnegative value.
+</FONT></P></P><H5><A name="4.9.7.5">4.9.7.5 The getc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int getc(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The getc function is equivalent to fgetc , except that if it is
+implemented as a macro, it may evaluate stream more than once, so the
+argument should never be an expression with side effects.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The getc function returns the next character from the input stream
+pointed to by stream . If the stream is at end-of-file, the
+end-of-file indicator for the stream is set and getc returns EOF . If
+a read error occurs, the error indicator for the stream is set and
+getc returns EOF .
+</FONT></P></P><H5><A name="4.9.7.6">4.9.7.6 The getchar function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int getchar(void);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The getchar function is equivalent to getc with the argument stdin .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The getchar function returns the next character from the input
+stream pointed to by stdin . If the stream is at end-of-file, the
+end-of-file indicator for the stream is set and getchar returns EOF .
+If a read error occurs, the error indicator for the stream is set and
+getchar returns EOF .
+</FONT></P></P><H5><A name="4.9.7.7">4.9.7.7 The gets function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ char *gets(char *s);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The gets function reads characters from the input stream pointed to
+by stdin , into the array pointed to by s , until end-of-file is
+encountered or a new-line character is read. Any new-line character
+is discarded, and a null character is written immediately after the
+last character read into the array.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The gets function returns s if successful. If end-of-file is
+encountered and no characters have been read into the array, the
+contents of the array remain unchanged and a null pointer is returned.
+If a read error occurs during the operation, the array contents are
+indeterminate and a null pointer is returned.
+</FONT></P></P><H5><A name="4.9.7.8">4.9.7.8 The putc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int putc(int c, FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The putc function is equivalent to fputc , except that if it is
+implemented as a macro, it may evaluate stream more than once, so the
+argument should never be an expression with side effects.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The putc function returns the character written. If a write error
+occurs, the error indicator for the stream is set and putc returns EOF.
+</FONT></P></P><H5><A name="4.9.7.9">4.9.7.9 The putchar function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int putchar(int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The putchar function is equivalent to putc with the second argument
+stdout.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The putchar function returns the character written. If a write
+error occurs, the error indicator for the stream is set and putchar
+returns EOF.
+</FONT></P></P><H5><A name="4.9.7.10">4.9.7.10 The puts function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int puts(const char *s);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The puts function writes the string pointed to by s to the stream
+pointed to by stdout , and appends a new-line character to the output.
+The terminating null character is not written.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The puts function returns EOF if a write error occurs; otherwise it
+returns a nonnegative value.
+</FONT></P></P><H5><A name="4.9.7.11">4.9.7.11 The ungetc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int ungetc(int c, FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The ungetc function pushes the character specified by c (converted
+to an unsigned char ) back onto the input stream pointed to by stream.
+The pushed-back characters will be returned by subsequent reads on
+that stream in the reverse order of their pushing. A successful
+intervening call (with the stream pointed to by stream ) to a file
+positioning function ( fseek , fsetpos , or rewind ) discards any
+pushed-back characters for the stream. The external storage
+corresponding to the stream is unchanged.
+</FONT></P><P>
+<FONT size="-1"> One character of pushback is guaranteed. If the ungetc function is
+called too many times on the same stream without an intervening read
+or file positioning operation on that stream, the operation may fail.
+</FONT></P><P>
+<FONT size="-1"> If the value of c equals that of the macro EOF , the operation
+fails and the input stream is unchanged.
+</FONT></P><P>
+<FONT size="-1"> A successful call to the ungetc function clears the end-of-file
+indicator for the stream. The value of the file position indicator
+for the stream after reading or discarding all pushed-back characters
+shall be the same as it was before the characters were pushed back.
+For a text stream, the value of its file position indicator after a
+successful call to the ungetc function is unspecified until all
+pushed-back characters are read or discarded. For a binary stream,
+its file position indicator is decremented by each successful call to
+the ungetc function; if its value was zero before a call, it is
+indeterminate after the call.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The ungetc function returns the character pushed back after
+conversion, or EOF if the operation fails.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ file positioning functions (<A href="
+ #4.9.9">4.9.9</A>).
+</FONT></P>
+
+<H4><A name="4.9.8">4.9.8 Direct input/output functions</A></H4>
+<H5><A name="4.9.8.1">4.9.8.1 The fread function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ size_t fread(void *ptr, size_t size, size_t nmemb,
+ FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fread function reads, into the array pointed to by ptr , up to
+nmemb members whose size is specified by size , from the stream
+pointed to by stream . The file position indicator for the stream (if
+defined) is advanced by the number of characters successfully read.
+If an error occurs, the resulting value of the file position indicator
+for the stream is indeterminate. If a partial member is read, its
+value is indeterminate.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fread function returns the number of members successfully read,
+which may be less than nmemb if a read error or end-of-file is
+encountered. If size or nmemb is zero, fread returns zero and the
+contents of the array and the state of the stream remain unchanged.
+</FONT></P></P><H5><A name="4.9.8.2">4.9.8.2 The fwrite function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ size_t fwrite(const void *ptr, size_t size, size_t nmemb,
+ FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fwrite function writes, from the array pointed to by ptr , up
+to nmemb members whose size is specified by size , to the stream
+pointed to by stream . The file position indicator for the stream (if
+defined) is advanced by the number of characters successfully written.
+If an error occurs, the resulting value of the file position indicator
+for the stream is indeterminate.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fwrite function returns the number of members successfully
+written, which will be less than nmemb only if a write error is
+encountered.
+</FONT></P></P><H4><A name="4.9.9">4.9.9 File positioning functions</A></H4>
+<H5><A name="4.9.9.1">4.9.9.1 The fgetpos function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fgetpos(FILE *stream, fpos_t *pos);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fgetpos function stores the current value of the file position
+indicator for the stream pointed to by stream in the object pointed to
+by pos . The value stored contains unspecified information usable by
+the fsetpos function for repositioning the stream to its position at
+the time of the call to the fgetpos function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If successful, the fgetpos function returns zero; on failure, the
+fgetpos function returns nonzero and stores an implementation-defined
+positive value in errno .
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the fsetpos function (<A href="
+ #4.9.9.3">4.9.9.3</A>).
+</FONT></P><H5><A name="4.9.9.2">4.9.9.2 The fseek function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fseek(FILE *stream, long int offset, int whence);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fseek function sets the file position indicator for the stream
+pointed to by stream .
+</FONT></P><P>
+<FONT size="-1"> For a binary stream, the new position, measured in characters from
+the beginning of the file, is obtained by adding offset to the
+position specified by whence. The specified point is the beginning
+of the file for SEEK_SET, the current value of the file position
+indicator for SEEK_CUR, or end-of-file for SEEK_END. A binary
+stream need not meaningfully support fseek calls with a whence value
+of SEEK_END.
+</FONT></P><P>
+<FONT size="-1"> For a text stream, either offset shall be zero, or offset shall be
+a value returned by an earlier call to the ftell function on the same
+stream and whence shall be SEEK_SET .
+</FONT></P><P>
+<FONT size="-1"> A successful call to the fseek function clears the end-of-file
+indicator for the stream and undoes any effects of the ungetc function
+on the same stream. After an fseek call, the next operation on an
+update stream may be either input or output.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The fseek function returns nonzero only for a request that cannot
+be satisfied.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the ftell function (<A href="
+ #4.9.9.4">4.9.9.4</A>).
+</FONT></P><H5><A name="4.9.9.3">4.9.9.3 The fsetpos function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int fsetpos(FILE *stream, const fpos_t *pos);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The fsetpos function sets the file position indicator for the
+stream pointed to by stream according to the value of the object
+pointed to by pos , which shall be a value returned by an earlier call
+to the fgetpos function on the same stream.
+</FONT></P><P>
+<FONT size="-1"> A successful call to the fsetpos function clears the end-of-file
+indicator for the stream and undoes any effects of the ungetc function
+on the same stream. After an fsetpos call, the next operation on an
+update stream may be either input or output.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If successful, the fsetpos function returns zero; on failure, the
+fsetpos function returns nonzero and stores an implementation-defined
+positive value in errno .
+</FONT></P></P><H5><A name="4.9.9.4">4.9.9.4 The ftell function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ long int ftell(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The ftell function obtains the current value of the file position
+indicator for the stream pointed to by stream . For a binary stream,
+the value is the number of characters from the beginning of the file.
+For a text stream, its file position indicator contains unspecified
+information, usable by the fseek function for returning the file
+position indicator for the stream to its position at the time of the
+ftell call; the difference between two such return values is not
+necessarily a meaningful measure of the number of characters written
+or read.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If successful, the ftell function returns the current value of the
+file position indicator for the stream. On failure, the ftell
+function returns -1L and stores an implementation-defined positive
+value in errno .
+</FONT></P></P><H5><A name="4.9.9.5">4.9.9.5 The rewind function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ void rewind(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The rewind function sets the file position indicator for the stream
+pointed to by stream to the beginning of the file. It is equivalent to
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> (void)fseek(stream, 0L, SEEK_SET)
+</FONT></P></PRE><P>
+<FONT size="-1">except that the error indicator for the stream is also cleared.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The rewind function returns no value.
+</FONT></P></P><H4><A name="4.9.10">4.9.10 Error-handling functions</A></H4>
+<H5><A name="4.9.10.1">4.9.10.1 The clearerr function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ void clearerr(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The clearerr function clears the end-of-file and error indicators
+for the stream pointed to by stream .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The clearerr function returns no value.
+</FONT></P></P><H5><A name="4.9.10.2">4.9.10.2 The feof function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int feof(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The feof function tests the end-of-file indicator for the stream
+pointed to by stream .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The feof function returns nonzero if and only if the end-of-file
+indicator is set for stream .
+</FONT></P></P><H5><A name="4.9.10.3">4.9.10.3 The ferror function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ int ferror(FILE *stream);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The ferror function tests the error indicator for the stream
+pointed to by stream .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The ferror function returns nonzero if and only if the error
+indicator is set for stream .
+</FONT></P></P><H5><A name="4.9.10.4">4.9.10.4 The perror function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ void perror(const char *s);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The perror function maps the error number in the integer expression
+errno to an error message. It writes a sequence of characters to the
+standard error stream thus: first (if s is not a null pointer and the
+character pointed to by s is not the null character), the string
+pointed to by s followed by a colon and a space; then an appropriate
+error message string followed by a new-line character. The contents
+of the error message strings are the same as those returned by the
+strerror function with argument errno , which are
+implementation-defined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The perror function returns no value.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the strerror function (<A href="
+ #4.11.6.2">4.11.6.2</A>).
+</FONT></P><H3><A name="4.10">4.10 GENERAL UTILITIES <stdlib.h></A></H3>
+<P>
+<FONT size="-1"> The header <stdlib.h> declares four types and several functions of
+general utility, and defines several macros.<SUP><A href="
+ #113">113</A></SUP></FONT></P><P>
+<FONT size="-1"> The types declared are size_t and wchar_t (both described in <A href="
+ #4.1.5">4.1.5</A>),
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> div_t
+</FONT></P></PRE><P>
+<FONT size="-1">which is a structure type that is the type of the value returned by
+the div function, and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> ldiv_t
+</FONT></P></PRE><P>
+<FONT size="-1">which is a structure type that is the type of the value returned by
+the ldiv function.
+</FONT></P><P>
+<FONT size="-1"> The macros defined are NULL (described in <A href="
+ #4.1.5">4.1.5</A>);
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> EXIT_FAILURE
+</FONT></P></PRE><P>
+<FONT size="-1">and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> EXIT_SUCCESS
+</FONT></P></PRE><P>
+<FONT size="-1">which expand to integral expressions that may be used as the argument
+to the exit function to return unsuccessful or successful termination
+status, respectively, to the host environment;
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> RAND_MAX
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to an integral constant expression, the value of which
+is the maximum value returned by the rand function; and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> MB_CUR_MAX
+</FONT></P></PRE><P>
+<FONT size="-1">which expands to a positive integer expression whose value is the
+maximum number of bytes in a multibyte character for the extended
+character set specified by the current locale (category LC_CTYPE ),
+and whose value is never greater than MB_LEN_MAX .
+</FONT></P><H4><A name="4.10.1">4.10.1 String conversion functions</A></H4>
+<P>
+<FONT size="-1"> The functions atof , atoi , and atol need not affect the value of
+the integer expression errno on an error. If the value of the result
+cannot be represented, the behavior is undefined.
+</FONT></P><H5><A name="4.10.1.1">4.10.1.1 The atof function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ double atof(const char *nptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The atof function converts the initial portion of the string
+pointed to by nptr to double representation. Except for the behavior
+on error, it is equivalent to
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> strtod(nptr, (char **)NULL)
+</FONT></P></PRE></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The atof function returns the converted value.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the strtod function (<A href="
+ #4.10.1.4">4.10.1.4</A>).
+</FONT></P><H5><A name="4.10.1.2">4.10.1.2 The atoi function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ int atoi(const char *nptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The atoi function converts the initial portion of the string
+pointed to by nptr to int representation. Except for the behavior on
+error, it is equivalent to
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> (int)strtol(nptr, (char **)NULL, 10)
+</FONT></P></PRE></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The atoi function returns the converted value.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the strtol function (<A href="
+ #4.10.1.5">4.10.1.5</A>).
+</FONT></P><H5><A name="4.10.1.3">4.10.1.3 The atol function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ long int atol(const char *nptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The atol function converts the initial portion of the string
+pointed to by nptr to long int representation. Except for the
+behavior on error, it is equivalent to
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> strtol(nptr, (char **)NULL, 10)
+</FONT></P></PRE></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The atol function returns the converted value.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the strtol function (<A href="
+ #4.10.1.5">4.10.1.5</A>).
+</FONT></P><H5><A name="4.10.1.4">4.10.1.4 The strtod function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ double strtod(const char *nptr, char **endptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strtod function converts the initial portion of the string
+pointed to by nptr to double representation. First it decomposes the
+input string into three parts: an initial, possibly empty, sequence of
+white-space characters (as specified by the isspace function), a
+subject sequence resembling a floating-point constant; and a final
+string of one or more unrecognized characters, including the
+terminating null character of the input string. Then it attempts to
+convert the subject sequence to a floating-point number, and returns
+the result.
+</FONT></P><P>
+<FONT size="-1"> The expected form of the subject sequence is an optional plus or
+minus sign, then a nonempty sequence of digits optionally containing a
+decimal-point character, then an optional exponent part as defined in
+<A href="
+ #3.1.3.1">3.1.3.1</A>, but no floating suffix. The subject sequence is defined as
+the longest subsequence of the input string, starting with the first
+non-white-space character, that is an initial subsequence of a
+sequence of the expected form. The subject sequence contains no
+characters if the input string is empty or consists entirely of white
+space, or if the first non-white-space character is other than a sign,
+a digit, or a decimal-point character.
+</FONT></P><P>
+<FONT size="-1"> If the subject sequence has the expected form, the sequence of
+characters starting with the first digit or the decimal-point
+character (whichever occurs first) is interpreted as a floating
+constant according to the rules of <A href="
+ #3.1.3.1">3.1.3.1</A>, except that the
+decimal-point character is used in place of a period, and that if
+neither an exponent part nor a decimal-point character appears, a
+decimal point is assumed to follow the last digit in the string. If
+the subject sequence begins with a minus sign, the value resulting
+from the conversion is negated. A pointer to the final string is
+stored in the object pointed to by endptr , provided that endptr is
+not a null pointer.
+</FONT></P><P>
+<FONT size="-1"> In other than the C locale, additional implementation-defined
+subject sequence forms may be accepted.
+</FONT></P><P>
+<FONT size="-1"> If the subject sequence is empty or does not have the expected
+form, no conversion is performed; the value of nptr is stored in the
+object pointed to by endptr , provided that endptr is not a null
+pointer.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strtod function returns the converted value, if any. If no
+conversion could be performed, zero is returned. If the correct value
+would cause overflow, plus or minus HUGE_VAL is returned (according to
+the sign of the value), and the value of the macro ERANGE is stored in
+errno . If the correct value would cause underflow, zero is returned
+and the value of the macro ERANGE is stored in errno .
+</FONT></P></P><H5><A name="4.10.1.5">4.10.1.5 The strtol function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ long int strtol(const char *nptr, char **endptr, int base);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strtol function converts the initial portion of the string
+pointed to by nptr to long int representation. First it decomposes
+the input string into three parts: an initial, possibly empty,
+sequence of white-space characters (as specified by the isspace
+function), a subject sequence resembling an integer represented in
+some radix determined by the value of base , and a final string of one
+or more unrecognized characters, including the terminating null
+character of the input string. Then it attempts to convert the
+subject sequence to an integer, and returns the result.
+</FONT></P><P>
+<FONT size="-1"> If the value of base is zero, the expected form of the subject
+sequence is that of an integer constant as described in <A href="
+ #3.1.3.2">3.1.3.2</A>,
+optionally preceded by a plus or minus sign, but not including an
+integer suffix. If the value of base is between 2 and 36, the
+expected form of the subject sequence is a sequence of letters and
+digits representing an integer with the radix specified by base ,
+optionally preceded by a plus or minus sign, but not including an
+integer suffix. The letters from a (or A ) through z (or Z ) are
+ascribed the values 10 to 35; only letters whose ascribed values are
+less than that of base are permitted. If the value of base is 16, the
+characters 0x or 0X may optionally precede the sequence of letters and
+digits, following the sign if present.
+</FONT></P><P>
+<FONT size="-1"> The subject sequence is defined as the longest subsequence of the
+input string, starting with the first non-white-space character, that
+is an initial subsequence of a sequence of the expected form. The
+subject sequence contains no characters if the input string is empty
+or consists entirely of white space, or if the first non-white-space
+character is other than a sign or a permissible letter or digit.
+</FONT></P><P>
+<FONT size="-1"> If the subject sequence has the expected form and the value of base
+is zero, the sequence of characters starting with the first digit is
+interpreted as an integer constant according to the rules of <A href="
+ #3.1.3.2">3.1.3.2</A>
+If the subject sequence has the expected form and the value of base is
+between 2 and 36, it is used as the base for conversion, ascribing to
+each letter its value as given above. If the subject sequence begins
+with a minus sign, the value resulting from the conversion is negated.
+A pointer to the final string is stored in the object pointed to by
+endptr , provided that endptr is not a null pointer.
+</FONT></P><P>
+<FONT size="-1"> In other than the C locale, additional implementation-defined
+subject sequence forms may be accepted.
+</FONT></P><P>
+<FONT size="-1"> If the subject sequence is empty or does not have the expected
+form, no conversion is performed; the value of nptr is stored in the
+object pointed to by endptr , provided that endptr is not a null
+pointer.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strtol function returns the converted value, if any. If no
+conversion could be performed, zero is returned. If the correct value
+would cause overflow, LONG_MAX or LONG_MIN is returned (according to
+the sign of the value), and the value of the macro ERANGE is stored in
+errno .
+</FONT></P></P><H5><A name="4.10.1.6">4.10.1.6 The strtoul function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ unsigned long int strtoul(const char *nptr, char **endptr,
+ int base);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strtoul function converts the initial portion of the string
+pointed to by nptr to unsigned long int representation. First it
+decomposes the input string into three parts: an initial, possibly
+empty, sequence of white-space characters (as specified by the isspace
+function), a subject sequence resembling an unsigned integer
+represented in some radix determined by the value of base , and a
+final string of one or more unrecognized characters, including the
+terminating null character of the input string. Then it attempts to
+convert the subject sequence to an unsigned integer, and returns the
+result.
+</FONT></P><P>
+<FONT size="-1"> If the value of base is zero, the expected form of the subject
+sequence is that of an integer constant as described in <A href="
+ #3.1.3.2">3.1.3.2</A>,
+optionally preceded by a plus or minus sign, but not including an
+integer suffix. If the value of base is between 2 and 36, the
+expected form of the subject sequence is a sequence of letters and
+digits representing an integer with the radix specified by base ,
+optionally preceded by a plus or minus sign, but not including an
+integer suffix. The letters from a (or A ) through z (or Z ) are
+ascribed the values 10 to 35; only letters whose ascribed values are
+less than that of base are permitted. If the value of base is 16, the
+characters 0x or 0X may optionally precede the sequence of letters and
+digits, following the sign if present.
+</FONT></P><P>
+<FONT size="-1"> The subject sequence is defined as the longest subsequence of the
+input string, starting with the first non-white-space character, that
+is an initial subsequence of a sequence of the expected form. The
+subject sequence contains no characters if the input string is empty
+or consists entirely of white space, or if the first non-white-space
+character is other than a sign or a permissible letter or digit.
+</FONT></P><P>
+<FONT size="-1"> If the subject sequence has the expected form and the value of base
+is zero, the sequence of characters starting with the first digit is
+interpreted as an integer constant according to the rules of <A href="
+ #3.1.3.2">3.1.3.2</A>
+If the subject sequence has the expected form and the value of base is
+between 2 and 36, it is used as the base for conversion, ascribing to
+each letter its value as given above. If the subject sequence begins
+with a minus sign, the value resulting from the conversion is negated.
+A pointer to the final string is stored in the object pointed to by
+endptr , provided that endptr is not a null pointer.
+</FONT></P><P>
+<FONT size="-1"> In other than the C locale, additional implementation-defined
+subject sequence forms may be accepted.
+</FONT></P><P>
+<FONT size="-1"> If the subject sequence is empty or does not have the expected
+form, no conversion is performed; the value of nptr is stored in the
+object pointed to by endptr , provided that endptr is not a null
+pointer.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strtoul function returns the converted value, if any. If no
+conversion could be performed, zero is returned. If the correct value
+would cause overflow, ULONG_MAX is returned, and the value of the
+macro ERANGE is stored in errno .
+</FONT></P></P><H4><A name="4.10.2">4.10.2 Pseudo-random sequence generation functions</A></H4>
+<H5><A name="4.10.2.1">4.10.2.1 The rand function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ int rand(void);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The rand function computes a sequence of pseudo-random integers in
+the range 0 to RAND_MAX .
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+rand function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The rand function returns a pseudo-random integer.
+</FONT></P><P>
+<FONT size="-1">"Environmental limit"
+</FONT></P><P>
+<FONT size="-1"> The value of the RAND_MAX macro shall be at least 32767.
+</FONT></P></P><H5><A name="4.10.2.2">4.10.2.2 The srand function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void srand(unsigned int seed);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The srand function uses the argument as a seed for a new sequence
+of pseudo-random numbers to be returned by subsequent calls to rand .
+If srand is then called with the same seed value, the sequence of
+pseudo-random numbers shall be repeated. If rand is called before any
+calls to srand have been made, the same sequence shall be generated as
+when srand is first called with a seed value of 1.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+srand function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The srand function returns no value.
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> The following functions define a portable implementation of rand
+and srand. Specifying the semantics makes it possible to determine
+reproducibly the behavior of programs that use pseudo-random
+sequences. This facilitates the testing of portable applications in
+different implementations.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> static unsigned long int next = 1;
+
+ int rand(void) /* RAND_MAX assumed to be 32767 */
+ {
+ next = next * 1103515245 + 12345;
+ return (unsigned int)(next/65536) % 32768;
+ }
+
+ void srand(unsigned int seed)
+ {
+ next = seed;
+ }
+</FONT></P></PRE></P><H4><A name="4.10.3">4.10.3 Memory management functions</A></H4>
+<P>
+<FONT size="-1"> The order and contiguity of storage allocated by successive calls
+to the calloc , malloc , and realloc functions is unspecified. The
+pointer returned if the allocation succeeds is suitably aligned so
+that it may be assigned to a pointer to any type of object and then
+used to access such an object in the space allocated (until the space
+is explicitly freed or reallocated). Each such allocation shall yield
+a pointer to an object disjoint from any other object. The pointer
+returned points to the start (lowest byte address) of the allocated
+space. If the space cannot be allocated, a null pointer is returned.
+If the size of the space requested is zero, the behavior is
+implementation-defined; the value returned shall be either a null
+pointer or a unique pointer. The value of a pointer that refers to
+freed space is indeterminate.
+</FONT></P><H5><A name="4.10.3.1">4.10.3.1 The calloc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void *calloc(size_t nmemb, size_t size);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The calloc function allocates space for an array of nmemb objects,
+each of whose size is size . The space is initialized to all bits
+zero.<SUP><A href="
+ #114">114</A></SUP></FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The calloc function returns either a null pointer or a pointer to
+the allocated space.
+</FONT></P></P><H5><A name="4.10.3.2">4.10.3.2 The free function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void free(void *ptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The free function causes the space pointed to by ptr to be
+deallocated, that is, made available for further allocation. If ptr
+is a null pointer, no action occurs. Otherwise, if the argument does
+not match a pointer earlier returned by the calloc , malloc , or
+realloc function, or if the space has been deallocated by a call to
+free or realloc , the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The free function returns no value.
+</FONT></P></P><H5><A name="4.10.3.3">4.10.3.3 The malloc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void *malloc(size_t size);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The malloc function allocates space for an object whose size is
+specified by size and whose value is indeterminate.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The malloc function returns either a null pointer or a pointer to
+the allocated space.
+</FONT></P></P><H5><A name="4.10.3.4">4.10.3.4 The realloc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void *realloc(void *ptr, size_t size);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The realloc function changes the size of the object pointed to by
+ptr to the size specified by size . The contents of the object shall
+be unchanged up to the lesser of the new and old sizes. If the new
+size is larger, the value of the newly allocated portion of the object
+is indeterminate. If ptr is a null pointer, the realloc function
+behaves like the malloc function for the specified size. Otherwise,
+if ptr does not match a pointer earlier returned by the calloc ,
+malloc , or realloc function, or if the space has been deallocated by
+a call to the free or realloc function, the behavior is undefined. If
+the space cannot be allocated, the object pointed to by ptr is
+unchanged. If size is zero and ptr is not a null pointer, the object
+it points to is freed.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The realloc function returns either a null pointer or a pointer to
+the possibly moved allocated space.
+</FONT></P></P><H4><A name="4.10.4">4.10.4 Communication with the environment</A></H4>
+<H5><A name="4.10.4.1">4.10.4.1 The abort function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void abort(void);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The abort function causes abnormal program termination to occur,
+unless the signal SIGABRT is being caught and the signal handler does
+not return. Whether open output streams are flushed or open streams
+closed or temporary files removed is implementation-defined. An
+implementation-defined form of the status unsuccessful termination is
+returned to the host environment by means of the function call
+raise(SIGABRT) .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The abort function cannot return to its caller.
+</FONT></P></P><H5><A name="4.10.4.2">4.10.4.2 The atexit function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ int atexit(void (*func)(void));
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The atexit function registers the function pointed to by func , to
+be called without arguments at normal program termination.
+</FONT></P><P>
+<FONT size="-1">"Implementation limits"
+</FONT></P><P>
+<FONT size="-1"> The implementation shall support the registration of at least 32
+functions.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The atexit function returns zero if the registration succeeds,
+nonzero if it fails.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the exit function (<A href="
+ #4.10.4.3">4.10.4.3</A>).
+</FONT></P><H5><A name="4.10.4.3">4.10.4.3 The exit function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void exit(int status);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The exit function causes normal program termination to occur. If
+more than one call to the exit function is executed by a program, the
+behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> First, all functions registered by the atexit function are called,
+in the reverse order of their registration.<SUP><A href="
+ #115">115</A></SUP></FONT></P><P>
+<FONT size="-1"> Next, all open output streams are flushed, all open streams are
+closed, and all files created by the tmpfile function are removed.
+</FONT></P><P>
+<FONT size="-1"> Finally, control is returned to the host environment. If the value
+of status is zero or EXIT_SUCCESS , an implementation-defined form of
+the status successful termination is returned. If the value of status
+is EXIT_FAILURE , an implementation-defined form of the status
+unsuccessful termination is returned. Otherwise the status returned
+is implementation-defined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The exit function cannot return to its caller.
+</FONT></P></P><H5><A name="4.10.4.4">4.10.4.4 The getenv function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ char *getenv(const char *name);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The getenv function searches an environment list, provided by the
+host environment, for a string that matches the string pointed to by
+name . The set of environment names and the method for altering the
+environment list are implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+getenv function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The getenv function returns a pointer to a string associated with
+the matched list member. The array pointed to shall not be modified
+by the program, but may be overwritten by a subsequent call to the
+getenv function. If the specified name cannot be found, a null
+pointer is returned.
+</FONT></P></P><H5><A name="4.10.4.5">4.10.4.5 The system function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ int system(const char *string);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The system function passes the string pointed to by string to the
+host environment to be executed by a command processor in an
+implementation-defined manner. A null pointer may be used for string
+to inquire whether a command processor exists.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If the argument is a null pointer, the system function returns
+nonzero only if a command processor is available. If the argument is
+not a null pointer, the system function returns an
+implementation-defined value.
+</FONT></P></P>
+
+<H4><A name="4.10.5">4.10.5 Searching and sorting utilities</A></H4>
+<H5><A name="4.10.5.1">4.10.5.1 The bsearch function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void *bsearch(const void *key, const void *base,
+ size_t nmemb, size_t size,
+ int (*compar)(const void *, const void *));
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The bsearch function searches an array of nmemb objects, the
+initial member of which is pointed to by base , for a member that
+matches the object pointed to by key . The size of each member of the
+array is specified by size .
+</FONT></P><P>
+<FONT size="-1"> The contents of the array shall be in ascending sorted order
+according to a comparison function pointed to by compar ,<SUP><A href="
+ #116">116</A></SUP> induces
+which is called with two arguments that point to the key object and to
+an array member, in that order. The function shall return an integer
+less than, equal to, or greater than zero if the key object is
+considered, respectively, to be less than, to match, or to be greater
+than the array member.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The bsearch function returns a pointer to a matching member of the
+array, or a null pointer if no match is found. If two members compare
+as equal, which member is matched is unspecified.
+</FONT></P></P><H5><A name="4.10.5.2">4.10.5.2 The qsort function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ void qsort(void *base, size_t nmemb, size_t size,
+ int (*compar)(const void *, const void *));
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The qsort function sorts an array of nmemb objects, the initial
+member of which is pointed to by base . The size of each object is
+specified by size .
+</FONT></P><P>
+<FONT size="-1"> The contents of the array are sorted in ascending order according
+to a comparison function pointed to by compar , which is called with
+two arguments that point to the objects being compared. The function
+shall return an integer less than, equal to, or greater than zero if
+the first argument is considered to be respectively less than, equal
+to, or greater than the second.
+</FONT></P><P>
+<FONT size="-1"> If two members compare as equal, their order in the sorted array is
+unspecified.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The qsort function returns no value.
+</FONT></P></P><H4><A name="4.10.6">4.10.6 Integer arithmetic functions</A></H4>
+<H5><A name="4.10.6.1">4.10.6.1 The abs function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ int abs(int j);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The abs function computes the absolute value of an integer j . If
+the result cannot be represented, the behavior is undefined.<SUP><A href="
+ #117">117</A></SUP></FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The abs function returns the absolute value.
+</FONT></P></P><H5><A name="4.10.6.2">4.10.6.2 The div function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ div_t div(int numer, int denom);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The div function computes the quotient and remainder of the
+division of the numerator numer by the denominator denom . If the
+division is inexact, the sign of the resulting quotient is that of the
+algebraic quotient, and the magnitude of the resulting quotient is the
+largest integer less than the magnitude of the algebraic quotient. If
+the result cannot be represented, the behavior is undefined;
+otherwise, quot * denom + rem shall equal numer .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The div function returns a structure of type div_t , comprising
+both the quotient and the remainder. The structure shall contain the
+following members, in either order.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int quot; /* quotient */
+ int rem; /* remainder */
+</FONT></P></PRE></P><H5><A name="4.10.6.3">4.10.6.3 The labs function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ long int labs(long int j);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The labs function is similar to the abs function, except that the
+argument and the returned value each have type long int .
+</FONT></P></P><H5><A name="4.10.6.4">4.10.6.4 The ldiv function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ ldiv_t ldiv(long int numer, long int denom);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The ldiv function is similar to the div function, except that the
+arguments and the members of the returned structure (which has type
+ldiv_t ) all have type long int .
+</FONT></P></P><H4><A name="4.10.7">4.10.7 Multibyte character functions</A></H4>
+<P>
+<FONT size="-1"> The behavior of the multibyte character functions is affected by
+the LC_CTYPE category of the current locale. For a state-dependent
+encoding, each function is placed into its initial state by a call for
+which its character pointer argument, s , is a null pointer.
+Subsequent calls with s as other than a null pointer cause the
+internal state of the function to be altered as necessary. A call
+with s as a null pointer causes these functions to return a nonzero
+value if encodings have state dependency, and zero otherwise. After
+the LC_CTYPE category is changed, the shift state of these functions
+is indeterminate.
+</FONT></P><H5><A name="4.10.7.1">4.10.7.1 The mblen function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ int mblen(const char *s, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> If s is not a null pointer, the mblen function determines the
+number of bytes comprising the multibyte character pointed to by s .
+Except that the shift state of the mbtowc function is not affected, it
+is equivalent to
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> mbtowc((wchar_t *)0, s, n);
+</FONT></P></PRE><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+mblen function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If s is a null pointer, the mblen function returns a nonzero or
+zero value, if multibyte character encodings, respectively, do or do
+not have state-dependent encodings. If s is not a null pointer, the
+mblen function either returns 0 (if s points to the null character),
+or returns the number of bytes that comprise the multibyte character
+(if the next n or fewer bytes form a valid multibyte character), or
+returns -1 (if they do not form a valid multibyte character).
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the mbtowc function (<A href="
+ #4.10.7.2">4.10.7.2</A>).
+</FONT></P><H5><A name="4.10.7.2">4.10.7.2 The mbtowc function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ int mbtowc(wchar_t *pwc, const char *s, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> If s is not a null pointer, the mbtowc function determines the
+number of bytes that comprise the multibyte character pointed to by s.
+It then determines the code for value of type wchar_t that
+corresponds to that multibyte character. (The value of the code
+corresponding to the null character is zero.) If the multibyte
+character is valid and pwc is not a null pointer, the mbtowc function
+stores the code in the object pointed to by pwc . At most n bytes of
+the array pointed to by s will be examined.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+mbtowc function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1">If s is a null pointer, the mbtowc function returns a nonzero or zero
+value, if multibyte character encodings, respectively, do or do not
+have state-dependent encodings. If s is not a null pointer, the
+mbtowc function either returns 0 (if s points to the null character),
+or returns the number of bytes that comprise the converted multibyte
+character (if the next n or fewer bytes form a valid multibyte
+character), or returns -1 (if they do not form a valid multibyte
+character).
+</FONT></P><P>
+<FONT size="-1"> In no case will the value returned be greater than n or the value
+of the MB_CUR_MAX macro.
+</FONT></P></P><H5><A name="4.10.7.3">4.10.7.3 The wctomb function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ int wctomb(char *s, wchar_t wchar);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The wctomb function determines the number of bytes needed to
+represent the multibyte character corresponding to the code whose
+value is wchar (including any change in shift state). It stores the
+multibyte character representation in the array object pointed to by s
+(if s is not a null pointer). At most MB_CUR_MAX characters are
+stored. If the value of wchar is zero, the wctomb function is left in
+the initial shift state.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+wctomb function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If s is a null pointer, the wctomb function returns a nonzero or
+zero value, if multibyte character encodings, respectively, do or do
+not have state-dependent encodings. If s is not a null pointer, the
+wctomb function returns -1 if the value of wchar does not correspond
+to a valid multibyte character, or returns the number of bytes that
+comprise the multibyte character corresponding to the value of wchar .
+</FONT></P><P>
+<FONT size="-1"> In no case will the value returned be greater than the value of the
+MB_CUR_MAX macro.
+</FONT></P></P><H4><A name="4.10.8">4.10.8 Multibyte string functions</A></H4>
+<P>
+<FONT size="-1"> The behavior of the multibyte string functions is affected by the
+LC_CTYPE category of the current locale.
+</FONT></P><H5><A name="4.10.8.1">4.10.8.1 The mbstowcs function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ size_t mbstowcs(wchar_t *pwcs, const char *s, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The mbstowcs function converts a sequence of multibyte characters
+that begins in the initial shift state from the array pointed to by s
+into a sequence of corresponding codes and stores not more than n
+codes into the array pointed to by pwcs . No multibyte characters
+that follow a null character (which is converted into a code with
+value zero) will be examined or converted. Each multibyte character
+is converted as if by a call to the mbtowc function, except that the
+shift state of the mbtowc function is not affected.
+</FONT></P><P>
+<FONT size="-1"> No more than n elements will be modified in the array pointed to by
+pwcs . If copying takes place between objects that overlap, the
+behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If an invalid multibyte character is encountered, the mbstowcs
+function returns (size_t)-1 . Otherwise, the mbstowcs function
+returns the number of array elements modified, not including a
+terminating zero code, if any.rN
+</FONT></P></P><H5><A name="4.10.8.2">4.10.8.2 The wcstombs function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <stdlib.h>
+ size_t wcstombs(char *s, const wchar_t *pwcs, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The wcstombs function converts a sequence of codes that correspond
+to multibyte characters from the array pointed to by pwcs into a
+sequence of multibyte characters that begins in the initial shift
+state and stores these multibyte characters into the array pointed to
+by s , stopping if a multibyte character would exceed the limit of n
+total bytes or if a null character is stored. Each code is converted
+as if by a call to the wctomb function, except that the shift state of
+the wctomb function is not affected.
+</FONT></P><P>
+<FONT size="-1"> No more than n bytes will be modified in the array pointed to by s
+. If copying takes place between objects that overlap, the behavior
+is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If a code is encountered that does not correspond to a valid
+multibyte character, the wcstombs function returns (size_t)-1 .
+Otherwise, the wcstombs function returns the number of bytes modified,
+not including a terminating null character, if any.rN
+</FONT></P></P><H3><A name="4.11">4.11 STRING HANDLING <string.h></A></H3>
+<H4><A name="4.11.1">4.11.1 String function conventions</A></H4>
+<P>
+<FONT size="-1"> The header <string.h> declares one type and several functions, and
+defines one macro useful for manipulating arrays of character type and
+other objects treated as arrays of character type.<SUP><A href="
+ #119">119</A></SUP> The type is
+size_t and the macro is NULL (both described in <A href="
+ #4.1.5">4.1.5</A>). Various
+methods are used for determining the lengths of the arrays, but in all
+cases a char * or void * argument points to the initial (lowest
+addressed) character of the array. If an array is accessed beyond the
+end of an object, the behavior is undefined.
+</FONT></P><H4><A name="4.11.2">4.11.2 Copying functions</A></H4>
+<H5><A name="4.11.2.1">4.11.2.1 The memcpy function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ void *memcpy(void *s1, const void *s2, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The memcpy function copies n characters from the object pointed to
+by s2 into the object pointed to by s1 . If copying takes place
+between objects that overlap, the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The memcpy function returns the value of s1 .
+</FONT></P></P><H5><A name="4.11.2.2">4.11.2.2 The memmove function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ void *memmove(void *s1, const void *s2, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The memmove function copies n characters from the object pointed to
+by s2 into the object pointed to by s1 . Copying takes place as if
+the n characters from the object pointed to by s2 are first copied
+into a temporary array of n characters that does not overlap the
+objects pointed to by s1 and s2 , and then the n characters from the
+temporary array are copied into the object pointed to by s1 .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The memmove function returns the value of s1 .
+</FONT></P></P><H5><A name="4.11.2.3">4.11.2.3 The strcpy function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strcpy(char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strcpy function copies the string pointed to by s2 (including
+the terminating null character) into the array pointed to by s1 . If
+copying takes place between objects that overlap, the behavior is
+undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strcpy function returns the value of s1 .
+</FONT></P></P><H5><A name="4.11.2.4">4.11.2.4 The strncpy function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strncpy(char *s1, const char *s2, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strncpy function copies not more than n characters (characters
+that follow a null character are not copied) from the array pointed to
+by s2 to the array pointed to by s1 .<SUP><A href="
+ #120">120</A></SUP> If copying takes place
+between objects that overlap, the behavior is undefined.
+</FONT></P><P>
+<FONT size="-1"> If the array pointed to by s2 is a string that is shorter than n
+characters, null characters are appended to the copy in the array
+pointed to by s1 , until n characters in all have been written.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strncpy function returns the value of s1 .
+</FONT></P></P><H4><A name="4.11.3">4.11.3 Concatenation functions</A></H4>
+<H5><A name="4.11.3.1">4.11.3.1 The strcat function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strcat(char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strcat function appends a copy of the string pointed to by s2
+(including the terminating null character) to the end of the string
+pointed to by s1 . The initial character of s2 overwrites the null
+character at the end of s1 . If copying takes place between objects
+that overlap, the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strcat function returns the value of s1 .
+</FONT></P></P><H5><A name="4.11.3.2">4.11.3.2 The strncat function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strncat(char *s1, const char *s2, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strncat function appends not more than n characters (a null
+character and characters that follow it are not appended) from the
+array pointed to by s2 to the end of the string pointed to by s1 .
+The initial character of s2 overwrites the null character at the end
+of s1 . A terminating null character is always appended to the
+result.<SUP><A href="
+ #121">121</A></SUP> If copying takes place between objects that overlap, the
+behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strncat function returns the value of s1 .
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the strlen function (<A href="
+ #4.11.6.3">4.11.6.3</A>).
+</FONT></P><H4><A name="4.11.4">4.11.4 Comparison functions</A></H4>
+<P>
+<FONT size="-1"> The sign of a nonzero value returned by the comparison functions is
+determined by the sign of the difference between the values of the
+first pair of characters (both interpreted as unsigned char ) that
+differ in the objects being compared.
+</FONT></P><H5><A name="4.11.4.1">4.11.4.1 The memcmp function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ int memcmp(const void *s1, const void *s2, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The memcmp function compares the first n characters of the object
+pointed to by s1 to the first n characters of the object pointed to by
+s2 .<SUP><A href="
+ #122">122</A></SUP></FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The memcmp function returns an integer greater than, equal to, or
+less than zero, according as the object pointed to by s1 is greater
+than, equal to, or less than the object pointed to by s2 .
+</FONT></P></P><H5><A name="4.11.4.2">4.11.4.2 The strcmp function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ int strcmp(const char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strcmp function compares the string pointed to by s1 to the
+string pointed to by s2 .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strcmp function returns an integer greater than, equal to, or
+less than zero, according as the string pointed to by s1 is greater
+than, equal to, or less than the string pointed to by s2 .
+</FONT></P></P><H5><A name="4.11.4.3">4.11.4.3 The strcoll function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ int strcoll(const char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1">The strcoll function compares the string pointed to by s1 to the
+string pointed to by s2 , both interpreted as appropriate to the
+LC_COLLATE category of the current locale.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strcoll function returns an integer greater than, equal to, or
+less than zero, according as the string pointed to by s1 is greater
+than, equal to, or less than the string pointed to by s2 when both are
+interpreted as appropriate to the current locale.
+</FONT></P></P><H5><A name="4.11.4.4">4.11.4.4 The strncmp function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ int strncmp(const char *s1, const char *s2, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strncmp function compares not more than n characters
+(characters that follow a null character are not compared) from the
+array pointed to by s1 to the array pointed to by s2 .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strncmp function returns an integer greater than, equal to, or
+less than zero, according as the possibly null-terminated array
+pointed to by s1 is greater than, equal to, or less than the possibly
+null-terminated array pointed to by s2 .
+</FONT></P></P><H5><A name="4.11.4.5">4.11.4.5 The strxfrm function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ size_t strxfrm(char *s1, const char *s2, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strxfrm function transforms the string pointed to by s2 and
+places the resulting string into the array pointed to by s1 . The
+transformation is such that if the strcmp function is applied to two
+transformed strings, it returns a value greater than, equal to, or
+less than zero, corresponding to the result of the strcoll function
+applied to the same two original strings. No more than n characters
+are placed into the resulting array pointed to by s1 , including the
+terminating null character. If n is zero, s1 is permitted to be a
+null pointer. If copying takes place between objects that overlap,
+the behavior is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strxfrm function returns the length of the transformed string
+(not including the terminating null character). If the value returned
+is n or more, the contents of the array pointed to by s1 are
+indeterminate.
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> The value of the following expression is the size of the array
+needed to hold the transformation of the string pointed to by s .
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> 1 + strxfrm(NULL, s, 0)
+</FONT></P></PRE></P><H4><A name="4.11.5">4.11.5 Search functions</A></H4>
+<H5><A name="4.11.5.1">4.11.5.1 The memchr function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ void *memchr(const void *s, int c, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The memchr function locates the first occurrence of c (converted to
+an unsigned char ) in the initial n characters (each interpreted as
+unsigned char ) of the object pointed to by s .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The memchr function returns a pointer to the located character, or
+a null pointer if the character does not occur in the object.
+</FONT></P></P><H5><A name="4.11.5.2">4.11.5.2 The strchr function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strchr(const char *s, int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strchr function locates the first occurrence of c (converted to
+a char ) in the string pointed to by s . The terminating null
+character is considered to be part of the string.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strchr function returns a pointer to the located character, or
+a null pointer if the character does not occur in the string.
+</FONT></P></P><H5><A name="4.11.5.3">4.11.5.3 The strcspn function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ size_t strcspn(const char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strcspn function computes the length of the maximum initial
+segment of the string pointed to by s1 which consists entirely of
+characters not from the string pointed to by s2 .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strcspn function returns the length of the segment.
+</FONT></P></P><H5><A name="4.11.5.4">4.11.5.4 The strpbrk function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strpbrk(const char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strpbrk function locates the first occurrence in the string
+pointed to by s1 of any character from the string pointed to by s2 .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strpbrk function returns a pointer to the character, or a null
+pointer if no character from s2 occurs in s1 .
+</FONT></P></P><H5><A name="4.11.5.5">4.11.5.5 The strrchr function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strrchr(const char *s, int c);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strrchr function locates the last occurrence of c (converted to
+a char ) in the string pointed to by s . The terminating null
+character is considered to be part of the string.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strrchr function returns a pointer to the character, or a null
+pointer if c does not occur in the string.
+</FONT></P></P><H5><A name="4.11.5.6">4.11.5.6 The strspn function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ size_t strspn(const char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strspn function computes the length of the maximum initial
+segment of the string pointed to by s1 which consists entirely of
+characters from the string pointed to by s2 .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strspn function returns the length of the segment.
+</FONT></P></P><H5><A name="4.11.5.7">4.11.5.7 The strstr function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strstr(const char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strstr function locates the first occurrence in the string
+pointed to by s1 of the sequence of characters (excluding the
+terminating null character) in the string pointed to by s2
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strstr function returns a pointer to the located string, or a
+null pointer if the string is not found. If s2 points to a string
+with zero length, the function returns s1 .
+</FONT></P></P><H5><A name="4.11.5.8">4.11.5.8 The strtok function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strtok(char *s1, const char *s2);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> A sequence of calls to the strtok function breaks the string
+pointed to by s1 into a sequence of tokens, each of which is delimited
+by a character from the string pointed to by s2 . The first call in
+the sequence has s1 as its first argument, and is followed by calls
+with a null pointer as their first argument. The separator string
+pointed to by s2 may be different from call to call.
+</FONT></P><P>
+<FONT size="-1"> The first call in the sequence searches the string pointed to by s1
+for the first character that is not contained in the current separator
+string pointed to by s2 . If no such character is found, then there
+are no tokens in the string pointed to by s1 and the strtok function
+returns a null pointer. If such a character is found, it is the start
+of the first token.
+</FONT></P><P>
+<FONT size="-1"> The strtok function then searches from there for a character that
+is contained in the current separator string. If no such character is
+found, the current token extends to the end of the string pointed to
+by s1 , and subsequent searches for a token will return a null
+pointer. If such a character is found, it is overwritten by a null
+character, which terminates the current token. The strtok function
+saves a pointer to the following character, from which the next search
+for a token will start.
+</FONT></P><P>
+<FONT size="-1"> Each subsequent call, with a null pointer as the value of the first
+argument, starts searching from the saved pointer and behaves as
+described above.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+strtok function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strtok function returns a pointer to the first character of a
+token, or a null pointer if there is no token.
+</FONT></P></P><H6>Example</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ static char str[] = "?a???b,,,#c";
+ char *t;
+
+ t = strtok(str, "?"); /* t points to the token "a" */
+ t = strtok(NULL, ","); /* t points to the token "??b" */
+ t = strtok(NULL, "#,"); /* t points to the token "c" */
+ t = strtok(NULL, "?"); /* t is a null pointer */
+</FONT></P></PRE></P>
+
+<H4><A name="4.11.6">4.11.6 Miscellaneous functions</A></H4>
+<H5><A name="4.11.6.1">4.11.6.1 The memset function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ void *memset(void *s, int c, size_t n);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The memset function copies the value of c (converted to an unsigned
+char ) into each of the first n characters of the object pointed to by
+s .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The memset function returns the value of s .
+</FONT></P></P><H5><A name="4.11.6.2">4.11.6.2 The strerror function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ char *strerror(int errnum);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strerror function maps the error number in errnum to an error
+message string.
+</FONT></P><P>
+<FONT size="-1"> The implementation shall behave as if no library function calls the
+strerror function.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strerror function returns a pointer to the string, the contents
+of which are implementation-defined. The array pointed to shall not
+be modified by the program, but may be overwritten by a subsequent
+call to the strerror function.
+</FONT></P></P><H5><A name="4.11.6.3">4.11.6.3 The strlen function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <string.h>
+ size_t strlen(const char *s);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strlen function computes the length of the string pointed to by s .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The strlen function returns the number of characters that precede
+the terminating null character.
+</FONT></P></P><H3><A name="4.12">4.12 DATE AND TIME <time.h></A></H3>
+<H4><A name="4.12.1">4.12.1 Components of time</A></H4>
+<P>
+<FONT size="-1"> The header <time.h> defines two macros, and declares four types and
+several functions for manipulating time. Many functions deal with a
+calendar time that represents the current date (according to the
+Gregorian calendar) and time. Some functions deal with local time,
+which is the calendar time expressed for some specific time zone, and
+with Daylight Saving Time, which is a temporary change in the
+algorithm for determining local time. The local time zone and
+Daylight Saving Time are implementation-defined.
+</FONT></P><P>
+<FONT size="-1"> The macros defined are NULL (described in <A href="
+ #4.1.5">4.1.5</A>); and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> CLK_TCK
+</FONT></P></PRE><P>
+<FONT size="-1">which is the number per second of the value returned by the clock function.
+</FONT></P><P>
+<FONT size="-1"> The types declared are size_t (described in <A href="
+ #4.1.5">4.1.5</A>);
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> clock_t
+</FONT></P></PRE><P>
+<FONT size="-1">and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> time_t
+</FONT></P></PRE><P>
+<FONT size="-1">which are arithmetic types capable of representing times; and
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> struct tm
+</FONT></P></PRE><P>
+<FONT size="-1">which holds the components of a calendar time, called the broken-down
+time. The structure shall contain at least the following members, in
+any order. The semantics of the members and their normal ranges are
+expressed in the comments.<SUP><A href="
+ #123">123</A></SUP></FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> int tm_sec; /* seconds after the minute --- [0, 60] */
+ int tm_min; /* minutes after the hour --- [0, 59] */
+ int tm_hour; /* hours since midnight --- [0, 23] */
+ int tm_mday; /* day of the month --- [1, 31] */
+ int tm_mon; /* months since January --- [0, 11] */
+ int tm_year; /* years since 1900 */
+ int tm_wday; /* days since Sunday --- [0, 6] */
+ int tm_yday; /* days since January 1 --- [0, 365] */
+ int tm_isdst; /* Daylight Saving Time flag */
+</FONT></P></PRE><P>
+<FONT size="-1">The value of tm_isdst is positive if Daylight Saving Time is in
+effect, zero if Daylight Saving Time is not in effect, and negative if
+the information is not available.
+</FONT></P><H4><A name="4.12.2">4.12.2 Time manipulation functions</A></H4>
+<H5><A name="4.12.2.1">4.12.2.1 The clock function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ clock_t clock(void);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The clock function determines the processor time used.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The clock function returns the implementation's best approximation
+to the processor time used by the program since the beginning of an
+implementation-defined era related only to the program invocation. To
+determine the time in seconds, the value returned by the clock
+function should be divided by the value of the macro CLK_TCK . If the
+processor time used is not available or its value cannot be
+represented, the function returns the value (clock_t)-1 .
+</FONT></P></P><H5><A name="4.12.2.2">4.12.2.2 The difftime function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ double difftime(time_t time1, time_t time0);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The difftime function computes the difference between two calendar
+times: time1 - time0 .
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The difftime function returns the difference expressed in seconds
+as a double .
+</FONT></P></P><H5><A name="4.12.2.3">4.12.2.3 The mktime function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ time_t mktime(struct tm *timeptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The mktime function converts the broken-down time, expressed as
+local time, in the structure pointed to by timeptr into a calendar
+time value with the same encoding as that of the values returned by
+the time function. The original values of the tm_wday and tm_yday
+components of the structure are ignored, and the original values of
+the other components are not restricted to the ranges indicated
+above.<SUP><A href="
+ #124">124</A></SUP> On successful completion, the values of the tm_wday and
+tm_yday components of the structure are set appropriately, and the
+other components are set to represent the specified calendar time, but
+with their values forced to the ranges indicated above; the final
+value of tm_mday is not set until tm_mon and tm_year are determined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The mktime function returns the specified calendar time encoded as
+a value of type time_t . If the calendar time cannot be represented,
+the function returns the value (time_t)-1 .
+</FONT></P></P><H6>Example</H6>
+<P>
+<P>
+<FONT size="-1"> What day of the week is July 4, 2001?
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #include <stdio.h>
+ #include <time.h>
+ static const char *const wday[] = {
+ "Sunday", "Monday", "Tuesday", "Wednesday",
+ "Thursday", "Friday", "Saturday", "-unknown-"
+ };
+ struct tm time_str;
+
+ time_str.tm_year = 2001 - 1900;
+ time_str.tm_mon = 7 - 1;
+ time_str.tm_mday = 4;
+ time_str.tm_hour = 0;
+ time_str.tm_min = 0;
+ time_str.tm_sec = 1;
+ time_str.tm_isdst = -1;
+ if (mktime(&time_str) == -1)
+ time_str.tm_wday = 7;
+ printf("%s\n", wday[time_str.tm_wday]);
+</FONT></P></PRE></P><H5><A name="4.12.2.4">4.12.2.4 The time function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ time_t time(time_t *timer);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The time function determines the current calendar time. The
+encoding of the value is unspecified.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The time function returns the implementation's best approximation
+to the current calendar time. The value (time_t)-1 is returned if the
+calendar time is not available. If timer is not a null pointer, the
+return value is also assigned to the object it points to.
+</FONT></P></P><H4><A name="4.12.3">4.12.3 Time conversion functions</A></H4>
+<P>
+<FONT size="-1"> Except for the strftime function, these functions return values in
+one of two static objects: a broken-down time structure and an array
+of char . Execution of any of the functions may overwrite the
+information returned in either of these objects by any of the other
+functions. The implementation shall behave as if no other library
+functions call these functions.
+</FONT></P><H5><A name="4.12.3.1">4.12.3.1 The asctime function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ char *asctime(const struct tm *timeptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The asctime function converts the broken-down time in the structure
+pointed to by timeptr into a string in the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> Sun Sep 16 01:03:52 1973\n\0
+</FONT></P></PRE><P>
+<FONT size="-1">using the equivalent of the following algorithm.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> char *asctime(const struct tm *timeptr)
+ {
+ static const char wday_name[7][3] = {
+ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+ };
+ static const char mon_name[12][3] = {
+ "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+ "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+ };
+ static char result[26];
+
+ sprintf(result, "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n",
+ wday_name[timeptr->tm_wday],
+ mon_name[timeptr->tm_mon],
+ timeptr->tm_mday, timeptr->tm_hour,
+ timeptr->tm_min, timeptr->tm_sec,
+ 1900 + timeptr->tm_year);
+ return result;
+ }
+</FONT></P></PRE></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The asctime function returns a pointer to the string.
+</FONT></P></P><H5><A name="4.12.3.2">4.12.3.2 The ctime function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ char *ctime(const time_t *timer);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The ctime function converts the calendar time pointed to by timer to local time in the form of a string. It is equivalent to
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> asctime(localtime(timer))
+</FONT></P></PRE></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The ctime function returns the pointer returned by the asctime
+function with that broken-down time as argument.
+</FONT></P></P><P>
+<FONT size="-1"><B>Forward references:</B>
+ the localtime function (<A href="
+ #4.12.3.4">4.12.3.4</A>).
+</FONT></P><H5><A name="4.12.3.3">4.12.3.3 The gmtime function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ struct tm *gmtime(const time_t *timer);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The gmtime function converts the calendar time pointed to by timer
+into a broken-down time, expressed as Coordinated Universal Time
+(UTC).
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The gmtime function returns a pointer to that object, or a null
+pointer if UTC is not available.
+</FONT></P></P><H5><A name="4.12.3.4">4.12.3.4 The localtime function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ struct tm *localtime(const time_t *timer);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The localtime function converts the calendar time pointed to by
+timer into a broken-down time, expressed as local time.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> The localtime function returns a pointer to that object.
+</FONT></P></P><H5><A name="4.12.3.5">4.12.3.5 The strftime function</A></H5>
+<H6>Synopsis</H6>
+<P>
+<PRE>
+<P class="code-block"><FONT size="+0"> #include <time.h>
+ size_t strftime(char *s, size_t maxsize,
+ const char *format, const struct tm *timeptr);
+</FONT></P></PRE></P><H6>Description</H6>
+<P>
+<P>
+<FONT size="-1"> The strftime function places characters into the array pointed to
+by s as controlled by the string pointed to by format . The format
+shall be a multibyte character sequence, beginning and ending in its
+initial shift state. The format string consists of zero or more
+conversion specifications and ordinary multibyte characters. A
+conversion specification consists of a % character followed by a
+character that determines the conversion specification's behavior.
+All ordinary multibyte characters (including the terminating null
+character) are copied unchanged into the array. If copying takes
+place between objects that overlap, the behavior is undefined. No
+more than maxsize characters are placed into the array. Each
+conversion specification is replaced by appropriate characters as
+described in the following list. The appropriate characters are
+determined by the program's locale and by the values contained in the
+structure pointed to by timeptr .
+</FONT></P><P>
+<FONT size="-1">"%a" is replaced by the locale's abbreviated weekday name.
+"%A" is replaced by the locale's full weekday name.
+"%b" is replaced by the locale's abbreviated month name.
+"%B" is replaced by the locale's full month name.
+"%c" is replaced by the locale's appropriate date and time representation.
+"%d" is replaced by the day of the month as a decimal number (01-31).
+"%H" is replaced by the hour (24-hour clock) as a decimal number (00-23).
+"%I" is replaced by the hour (12-hour clock) as a decimal number (01-12).
+"%j" is replaced by the day of the year as a decimal number (001-366 ).
+"%m" is replaced by the month as a decimal number (01-12).
+"%M" is replaced by the minute as a decimal number (00-59).
+"%p" is replaced by the locale's equivalent of either AM or PM .
+"%S" is replaced by the second as a decimal number (00-60).
+"%U" is replaced by the week number of the year (ithe first Sunday as the
+ first day of week 1) as a decimal number (00-53).
+"%w" is replaced by the weekday as a decimal number (0-6), where Sunday is
+ 0.
+"%W" is replaced by the week number of the year (the first Monday as the
+ first day of week 1) as a decimal number (00-53).
+"%x" is replaced by the locale's appropriate date representation.
+"%X" is replaced by the locale's appropriate time representation.
+"%y" is replaced by the year without century as a decimal number (00-99).
+"%Y" is replaced by the year with century as a decimal number.
+"%Z" is replaced by the time zone name, or by no characters if no time
+ zone is determinable.
+"%%" is replaced by %.
+</FONT></P><P>
+<FONT size="-1"> If a conversion specification is not one of the above, the behavior
+is undefined.
+</FONT></P></P><H6>Returns</H6>
+<P>
+<P>
+<FONT size="-1"> If the total number of resulting characters including the
+terminating null character is not more than maxsize , the strftime
+function returns the number of characters placed into the array
+pointed to by s not including the terminating null character.
+Otherwise, zero is returned and the contents of the array are
+indeterminate.
+</FONT></P></P><H3><A name="4.13">4.13 FUTURE LIBRARY DIRECTIONS</A></H3>
+<P>
+<FONT size="-1"> The following names are grouped under individual headers for
+convenience. All external names described below are reserved no
+matter what headers are included by the program.
+</FONT></P><H4><A name="4.13.1">4.13.1 Errors <errno.h></A></H4>
+<P>
+<FONT size="-1"> Macros that begin with E and a digit or E and an upper-case letter
+(followed by any combination of digits, letters and underscore) may be
+added to the declarations in the <errno.h> header.
+</FONT></P><H4><A name="4.13.2">4.13.2 Character handling <ctype.h></A></H4>
+<P>
+<FONT size="-1"> Function names that begin with either is or to , and a lower-case
+letter (followed by any combination of digits, letters and underscore)
+may be added to the declarations in the <ctype.h> header.
+</FONT></P><H4><A name="4.13.3">4.13.3 Localization <locale.h></A></H4>
+<P>
+<FONT size="-1"> Macros that begin with LC_ and an upper-case letter (followed by
+any combination of digits, letters and underscore) may be added to the
+definitions in the <locale.h> header.
+</FONT></P><H4><A name="4.13.4">4.13.4 Mathematics <math.h></A></H4>
+<P>
+<FONT size="-1"> The names of all existing functions declared in the <math.h>
+header, suffixed with f or l , are reserved respectively for
+corresponding functions with float and long double arguments and
+return values.
+</FONT></P><H4><A name="4.13.5">4.13.5 Signal handling <signal.h></A></H4>
+<P>
+<FONT size="-1"> Macros that begin with either SIG and an upper-case letter or SIG_
+and an upper-case letter (followed by any combination of digits,
+letters and underscore) may be added to the definitions in the
+<signal.h> header.
+</FONT></P><H4><A name="4.13.6">4.13.6 Input/output <stdio.h></A></H4>
+<P>
+<FONT size="-1"> Lower-case letters may be added to the conversion specifiers in
+fprintf and fscanf . Other characters may be used in extensions.
+</FONT></P><H4><A name="4.13.7">4.13.7 General utilities <stdlib.h></A></H4>
+<P>
+<FONT size="-1"> Function names that begin with str and a lower-case letter
+(followed by any combination of digits, letters and underscore) may be
+added to the declarations in the <stdlib.h> header.
+</FONT></P><H4><A name="4.13.8">4.13.8 String handling <string.h></A></H4>
+<P>
+<FONT size="-1"> Function names that begin with str , mem , or wcs and a lower-case
+letter (followed by any combination of digits, letters and underscore)
+may be added to the declarations in the <string.h> header.
+</FONT></P><H2><A name="A.">A. APPENDICES</A></H2>
+<P>
+<FONT size="-1"> (These appendices are not a part of American National Standard for
+Information Systems --- Programming Language C, X3.???-1988.)
+</FONT></P><P>
+<FONT size="-1"> These appendices collect information that appears in the Standard,
+and are not necessarily complete.
+</FONT></P><H3><A name="A.1">A.1 LANGUAGE SYNTAX SUMMARY</A></H3>
+<P>
+<FONT size="-1"> The notation is described in the introduction to <A href="
+ #3.">3.</A> (Language).
+</FONT></P><H4><A name="A.1.1">A.1.1 Lexical grammar</A></H4>
+<H5><A name="A.1.1.1">A.1.1.1 Tokens</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> keyword
+ identifier
+ constant
+ string-literal
+ operator
+ punctuator
+ header-name
+ identifier
+ pp-number
+ character-constant
+ string-literal
+ operator
+ punctuator
+ each non-white-space character that cannot be one of the above
+</FONT></P></PRE><H5><A name="A.1.1.2">A.1.1.2 Keywords</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> auto double int struct
+ break else long switch
+ case enum register typedef
+ char extern return union
+ const float short unsigned
+ continue for signed void
+ default goto sizeof volatile
+ do if static while
+</FONT></P></PRE><H5><A name="A.1.1.3">A.1.1.3 Identifiers</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> nondigit
+ identifier nondigit
+ identifier digit
+
+ _ a b c d e f g h i j k l m
+ n o p q r s t u v w x y z
+ A B C D E F G H I J K L M
+ N O P Q R S T U V W X Y Z
+
+ 0 1 2 3 4 5 6 7 8 9
+</FONT></P></PRE><H5><A name="A.1.1.4">A.1.1.4 Constants</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> floating-constant
+ integer-constant
+ enumeration-constant
+ character-constant
+
+ fractional-constant exponent-part<opt> floating-suffix<opt>
+ digit-sequence exponent-part floating-suffix<opt>
+
+ digit-sequence<opt> . digit-sequence
+ digit-sequence .
+
+ e sign<opt> digit-sequence
+ E sign<opt> digit-sequence
+
+ + -
+
+ digit
+ digit-sequence digit
+
+ f l F L
+
+ decimal-constant integer-suffix<opt>
+ octal-constant integer-suffix<opt>
+ hexadecimal-constant integer-suffix<opt>
+
+ nonzero-digit
+ decimal-constant digit
+
+ 0
+ octal-constant octal-digit
+
+ 0x hexadecimal-digit
+ 0X hexadecimal-digit
+ hexadecimal-constant hexadecimal-digit
+
+ 1 2 3 4 5 6 7 8 9
+
+ 0 1 2 3 4 5 6 7
+
+ 0 1 2 3 4 5 6 7 8 9
+ a b c d e f
+ A B C D E F
+
+ unsigned-suffix long-suffix<opt>
+ long-suffix unsigned-suffix<opt>
+
+ u U
+
+ l L
+
+ identifier
+
+ ' c-char-sequence'
+ L' c-char-sequence'
+
+ c-char
+ c-char-sequence c-char
+
+ any member of the source character set except
+ the single-quote ', backslash \, or new-line character
+ escape-sequence
+
+ simple-escape-sequence
+ octal-escape-sequence
+ hexadecimal-escape-sequence
+
+ \' \" \? \\
+ \a \b \f \n \r \t \v
+
+ \ octal-digit
+ \ octal-digit octal-digit
+ \ octal-digit octal-digit octal-digit
+
+ \x hexadecimal-digit
+ hexadecimal-escape-sequence hexadecimal-digit
+</FONT></P></PRE><H5><A name="A.1.1.5">A.1.1.5 String literals</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> " s-char-sequence<opt>"
+ L" s-char-sequence<opt>"
+
+ s-char
+ s-char-sequence s-char
+
+ any member of the source character set except
+ the double-quote ", backslash \, or new-line character
+ escape-sequence
+</FONT></P></PRE><H5><A name="A.1.1.6">A.1.1.6 Operators</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> [ ] ( ) . ->
+ ++ -- & * + - ~ ! sizeof
+ / % << >> < > <= >= == != ^ | && ||
+ ? :
+ = *= /= %= += -= <<= >>= &= ^= |=
+ , # ##
+</FONT></P></PRE><H5><A name="A.1.1.7">A.1.1.7 Punctuators</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> [ ] ( ) { } * , : = ; ... #
+</FONT></P></PRE><H5><A name="A.1.1.8">A.1.1.8 Header names</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> < h-char-sequence>
+ " q-char-sequence"
+
+ h-char
+ h-char-sequence h-char
+
+ any member of the source character set except
+ the new-line character and >
+
+ q-char
+ q-char-sequence q-char
+
+ any member of the source character set except
+ the new-line character and "
+</FONT></P></PRE><H5><A name="A.1.1.9">A.1.1.9 Preprocessing numbers</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> digit
+ . digit
+ pp-number digit
+ pp-number nondigit
+ pp-number e sign
+ pp-number E sign
+ pp-number .
+</FONT></P></PRE><H4><A name="A.1.2">A.1.2 Phrase structure grammar</A></H4>
+<H5><A name="A.1.2.1">A.1.2.1 Expressions</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> identifier
+ constant
+ string-literal
+ ( expression )
+
+ primary-expression
+ postfix-expression [ expression ]
+ postfix-expression ( argument-expression-list<opt> )
+ postfix-expression . identifier
+ postfix-expression -> identifier
+ postfix-expression ++
+ postfix-expression --
+
+ assignment-expression
+ argument-expression-list , assignment-expression
+
+ postfix-expression
+ ++ unary-expression
+ -- unary-expression
+ unary-operator cast-expression
+ sizeof unary-expression
+ sizeof ( type-name )
+
+ & * + - ~ !
+
+ unary-expression
+ ( type-name ) cast-expression
+
+ cast-expression
+ multiplicative-expression * cast-expression
+ multiplicative-expression / cast-expression
+ multiplicative-expression % cast-expression
+
+ multiplicative-expression
+ additive-expression + multiplicative-expression
+ additive-expression - multiplicative-expression
+
+ additive-expression
+ shift-expression << additive-expression
+ shift-expression >> additive-expression
+
+ shift-expression
+ relational-expression < shift-expression
+ relational-expression > shift-expression
+ relational-expression <= shift-expression
+ relational-expression >= shift-expression
+
+ relational-expression
+ equality-expression == relational-expression
+ equality-expression != relational-expression
+
+ equality-expression
+ AND-expression & equality-expression
+
+ AND-expression
+ exclusive-OR-expression ^ AND-expression
+
+ exclusive-OR-expression
+ inclusive-OR-expression | exclusive-OR-expression
+
+ inclusive-OR-expression
+ logical-AND-expression && inclusive-OR-expression
+
+ logical-AND-expression
+ logical-OR-expression || logical-AND-expression
+
+ logical-OR-expression
+ logical-OR-expression ? expression : conditional-expression
+
+ conditional-expression
+ unary-expression assignment-operator assignment-expression
+
+ = *= /= %= += -= <<= >>= &= ^= |=
+
+ assignment-expression
+ expression , assignment-expression
+
+ conditional-expression
+</FONT></P></PRE><H5><A name="A.1.2.2">A.1.2.2 Declarations</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> declaration-specifiers init-declarator-list<opt> ;
+
+ storage-class-specifier declaration-specifiers<opt>
+ type-specifier declaration-specifiers<opt>
+ type-qualifier declaration-specifiers<opt>
+
+ init-declarator
+ init-declarator-list , init-declarator
+
+ declarator
+ declarator = initializer
+
+ typedef
+ extern
+ static
+ auto
+ register
+
+ void
+ char
+ short
+ int
+ long
+ float
+ double
+ signed
+ unsigned
+ struct-or-union-specifier
+ enum-specifier
+ typedef-name
+
+ struct-or-union identifier<opt> { struct-declaration-list }
+ struct-or-union identifier
+
+ struct
+ union
+
+ struct-declaration
+ struct-declaration-list struct-declaration
+
+ specifier-qualifier-list struct-declarator-list ;
+
+ type-specifier specifier-qualifier-list<opt>
+ type-qualifier specifier-qualifier-list<opt>
+
+ struct-declarator
+ struct-declarator-list , struct-declarator
+
+ declarator
+ declarator<opt> : constant-expression
+
+ enum identifier<opt> { enumerator-list }
+ enum identifier
+
+ enumerator
+ enumerator-list , enumerator
+
+ enumeration-constant
+ enumeration-constant = constant-expression
+
+ const
+ volatile
+
+ pointer<opt> direct-declarator
+
+ identifier
+ ( declarator )
+ direct-declarator [ constant-expression<opt> ]
+
+ direct-declarator ( parameter-type-list )
+ direct-declarator ( identifier-list<opt> )
+
+ * type-qualifier-list<opt>
+ * type-qualifier-list<opt> pointer
+
+ type-qualifier
+ type-qualifier-list type-qualifier
+
+ parameter-list
+ parameter-list , ...
+
+ parameter-declaration
+ parameter-list , parameter-declaration
+
+ declaration-specifiers declarator
+ declaration-specifiers abstract-declarator<opt>
+
+ identifier
+ identifier-list , identifier
+
+ specifier-qualifier-list abstract-declarator<opt>
+
+ pointer
+ pointer<opt> direct-abstract-declarator
+
+ ( abstract-declarator )
+ direct-abstract-declarator<opt> [ constant-expression<opt> ]
+ direct-abstract-declarator<opt> ( parameter-type-list<opt> )
+
+ identifier
+
+ assignment-expression
+ { initializer-list }
+ { initializer-list , }
+
+ initializer
+ initializer-list , initializer
+</FONT></P></PRE><H5><A name="A.1.2.3">A.1.2.3 Statements</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> labeled-statement
+ compound-statement
+ expression-statement
+ selection-statement
+ iteration-statement
+ jump-statement
+
+ identifier : statement
+ case constant-expression : statement
+ default : statement
+
+ { declaration-list<opt> statement-list<opt> }
+
+ declaration
+ declaration-list declaration
+
+ statement
+ statement-list statement
+
+ expression<opt> ;
+
+ if ( expression ) statement
+ if ( expression ) statement else statement
+ switch ( expression ) statement
+
+ while ( expression ) statement
+ do statement while ( expression ) ;
+ for ( expression<opt> ; expression<opt> ;
+ expression<opt> ) statement
+
+ goto identifier ;
+ continue ;
+ break ;
+ return expression<opt> ;
+</FONT></P></PRE><H5><A name="A.1.2.4">A.1.2.4 External definitions</A></H5>
+<PRE>
+<P class="code-block"><FONT size="+0"> external-declaration
+ translation-unit external-declaration
+
+ function-definition
+ declaration
+
+ declaration-specifiers<opt> declarator
+ declaration-list<opt> compound-statement
+</FONT></P></PRE><H4><A name="A.1.3">A.1.3 Preprocessing directives</A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> group<opt>
+
+ group-part
+ group group-part
+
+ pp-tokens<opt> new-line
+ if-section
+ control-line
+
+ if-group elif-groups<opt> else-group<opt> endif-line
+
+ # if constant-expression new-line group<opt>
+ # ifdef identifier new-line group<opt>
+ # ifndef identifier new-line group<opt>
+
+ elif-group
+ elif-groups elif-group
+
+ # elif constant-expression new-line group<opt>
+
+ # else new-line group<opt>
+
+ # endif new-line
+
+ control-line:
+
+ the left-parenthesis character without preceding white space
+
+ pp-tokens<opt>
+
+ preprocessing-token
+ pp-tokens preprocessing-token
+
+ the new-line character
+</FONT></P></PRE>
+
+<H3><A name="A.2">A.2 SEQUENCE POINTS</A></H3>
+<P>
+<FONT size="-1"> The following are the sequence points described in <A href="
+ #2.1.2.3">2.1.2.3</A></FONT></P><P>
+<FONT size="-1"> * The call to a function, after the arguments have been evaluated
+ (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The end of the first operand of the following operators: logical
+ AND && (<A href="
+ #3.3.13">3.3.13</A>); logical OR || (<A href="
+ #3.3.14">3.3.14</A>); conditional ? (<A href="
+ #3.3.15">3.3.15</A>);
+ comma , (<A href="
+ #3.3.17">3.3.17</A>).
+</FONT></P><P>
+<FONT size="-1"> * The end of a full expression: an initializer (<A href="
+ #3.5.7">3.5.7</A>); the
+ expression in an expression statement (<A href="
+ #3.6.3">3.6.3</A>); the controlling
+ expression of a selection statement ( if or switch ) (<A href="
+ #3.6.4">3.6.4</A>); the
+ controlling expression of a while or do statement (<A href="
+ #3.6.5">3.6.5</A>); the three
+ expressions of a for statement (<A href="
+ #3.6.5.3">3.6.5.3</A>); the expression in a return
+ statement (<A href="
+ #3.6.6.4">3.6.6.4</A>).
+</FONT></P><H3><A name="A.3">A.3 LIBRARY SUMMARY</A></H3>
+<H4><A name="A.3.1">A.3.1 ERRORS <errno.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> EDOM
+ ERANGE
+ errno
+</FONT></P></PRE><H4><A name="A.3.2">A.3.2 COMMON DEFINITIONS <stddef.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> NULL
+ offsetof( type, member-designator)
+ ptrdiff_t
+ size_t
+ wchar_t
+</FONT></P></PRE><H4><A name="A.3.3">A.3.3 DIAGNOSTICS <assert.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> NDEBUG
+ void assert(int expression);
+</FONT></P></PRE><H4><A name="A.3.4">A.3.4 CHARACTER HANDLING <ctype.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> int isalnum(int c);
+ int isalpha(int c);
+ int iscntrl(int c);
+ int isdigit(int c);
+ int isgraph(int c);
+ int islower(int c);
+ int isprint(int c);
+ int ispunct(int c);
+ int isspace(int c);
+ int isupper(int c);
+ int isxdigit(int c);
+ int tolower(int c);
+ int toupper(int c);
+</FONT></P></PRE><H4><A name="A.3.5">A.3.5 LOCALIZATION <locale.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> LC_ALL
+ LC_COLLATE
+ LC_CTYPE
+ LC_MONETARY
+ LC_NUMERIC
+ LC_TIME
+ NULL
+ struct lconv
+ char *setlocale(int category, const char *locale);
+ struct lconv *localeconv(void);
+</FONT></P></PRE><H4><A name="A.3.6">A.3.6 MATHEMATICS <math.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> HUGE_VAL
+ double acos(double x);
+ double asin(double x);
+ double atan(double x);
+ double atan2(double y, double x);
+ double cos(double x);
+ double sin(double x);
+ double tan(double x);
+ double cosh(double x);
+ double sinh(double x);
+ double tanh(double x);
+ double exp(double x);
+ double frexp(double value, int *exp);
+ double ldexp(double x, int exp);
+ double log(double x);
+ double log10(double x);
+ double modf(double value, double *iptr);
+ double pow(double x, double y);
+ double sqrt(double x);
+ double ceil(double x);
+ double fabs(double x);
+ double floor(double x);
+ double fmod(double x, double y);
+</FONT></P></PRE><H4><A name="A.3.7">A.3.7 NON-LOCAL JUMPS <setjmp.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> jmp_buf
+ int setjmp(jmp_buf env);
+ void longjmp(jmp_buf env, int val);
+</FONT></P></PRE><H4><A name="A.3.8">A.3.8 SIGNAL HANDLING <signal.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> sig_atomic_t
+ SIG_DFL
+ SIG_ERR
+ SIG_IGN
+ SIGABRT
+ SIGFPE
+ SIGILL
+ SIGINT
+ SIGSEGV
+ SIGTERM
+ void (*signal(int sig, void (*func)(int)))(int);
+ int raise(int sig);
+</FONT></P></PRE><H4><A name="A.3.9">A.3.9 VARIABLE ARGUMENTS <stdarg.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> va_list
+ void va_start(va_list ap, parmN);
+ type va_arg(va_list ap, type);
+ void va_end(va_list ap);
+</FONT></P></PRE><H4><A name="A.3.10">A.3.10 INPUT/OUTPUT <stdio.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> _IOFBF
+ _IOLBF
+ _IONBF
+ BUFSIZ
+ EOF
+ FILE
+ FILENAME_MAX
+ FOPEN_MAX
+ fpos_t
+ L_tmpnam
+ NULL
+ SEEK_CUR
+ SEEK_END
+ SEEK_SET
+ size_t
+ stderr
+ stdin
+ stdout
+ TMP_MAX
+ int remove(const char *filename);
+ int rename(const char *old, const char *new);
+ FILE *tmpfile(void);
+ char *tmpnam(char *s);
+ int fclose(FILE *stream);
+ int fflush(FILE *stream);
+ FILE *fopen(const char *filename, const char *mode);
+ FILE *freopen(const char *filename, const char *mode,
+ FILE *stream);
+ void setbuf(FILE *stream, char *buf);
+ int setvbuf(FILE *stream, char *buf, int mode, size_t size);
+ int fprintf(FILE *stream, const char *format, ...);
+ int fscanf(FILE *stream, const char *format, ...);
+ int printf(const char *format, ...);
+ int scanf(const char *format, ...);
+ int sprintf(char *s, const char *format, ...);
+ int sscanf(const char *s, const char *format, ...);
+ int vfprintf(FILE *stream, const char *format, va_list arg);
+ int vprintf(const char *format, va_list arg);
+ int vsprintf(char *s, const char *format, va_list arg);
+ int fgetc(FILE *stream);
+ char *fgets(char *s, int n, FILE *stream);
+ int fputc(int c, FILE *stream);
+ int fputs(const char *s, FILE *stream);
+ int getc(FILE *stream);
+ int getchar(void);
+ char *gets(char *s);
+ int putc(int c, FILE *stream);
+ int putchar(int c);
+ int puts(const char *s);
+ int ungetc(int c, FILE *stream);
+ size_t fread(void *ptr, size_t size, size_t nmemb,
+ FILE *stream);
+ size_t fwrite(const void *ptr, size_t size, size_t nmemb,
+ FILE *stream);
+ int fgetpos(FILE *stream, fpos_t *pos);
+ int fseek(FILE *stream, long int offset, int whence);
+ int fsetpos(FILE *stream, const fpos_t *pos);
+ long int ftell(FILE *stream);
+ void rewind(FILE *stream);
+ void clearerr(FILE *stream);
+ int feof(FILE *stream);
+ int ferror(FILE *stream);
+ void perror(const char *s);
+</FONT></P></PRE><H4><A name="A.3.11">A.3.11 GENERAL UTILITIES <stdlib.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> EXIT_FAILURE
+ EXIT_SUCCESS
+ MB_CUR_MAX
+ NULL
+ RAND_MAX
+ div_t
+ ldiv_t
+ size_t
+ wchar_t
+ double atof(const char *nptr);
+ int atoi(const char *nptr);
+ long int atol(const char *nptr);
+ double strtod(const char *nptr, char **endptr);
+ long int strtol(const char *nptr, char **endptr, int base);
+ unsigned long int strtoul(const char *nptr, char **endptr,
+ int base);
+ int rand(void);
+ void srand(unsigned int seed);
+ void *calloc(size_t nmemb, size_t size);
+ void free(void *ptr);
+ void *malloc(size_t size);
+ void *realloc(void *ptr, size_t size);
+ void abort(void);
+ int atexit(void (*func)(void));
+ void exit(int status);
+ char *getenv(const char *name);
+ int system(const char *string);
+ void *bsearch(const void *key, const void *base,
+ size_t nmemb, size_t size,
+ int (*compar)(const void *, const void *));
+ void qsort(void *base, size_t nmemb, size_t size,
+ int (*compar)(const void *, const void *));
+ int abs(int j);
+ div_t div(int numer, int denom);
+ long int labs(long int j);
+ ldiv_t ldiv(long int numer, long int denom);
+ int mblen(const char *s, size_t n);
+ int mbtowc(wchar_t *pwc, const char *s, size_t n);
+ int wctomb(char *s, wchar_t wchar);
+ size_t mbstowcs(wchar_t *pwcs, const char *s, size_t n);
+ size_t wcstombs(char *s, const wchar_t *pwcs, size_t n);
+</FONT></P></PRE><H4><A name="A.3.12">A.3.12 STRING HANDLING <string.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> NULL
+ size_t
+ void *memcpy(void *s1, const void *s2, size_t n);
+ void *memmove(void *s1, const void *s2, size_t n);
+ char *strcpy(char *s1, const char *s2);
+ char *strncpy(char *s1, const char *s2, size_t n);
+ char *strcat(char *s1, const char *s2);
+ char *strncat(char *s1, const char *s2, size_t n);
+ int memcmp(const void *s1, const void *s2, size_t n);
+ int strcmp(const char *s1, const char *s2);
+ int strcoll(const char *s1, const char *s2);
+ int strncmp(const char *s1, const char *s2, size_t n);
+ size_t strxfrm(char *s1, const char *s2, size_t n);
+ void *memchr(const void *s, int c, size_t n);
+ char *strchr(const char *s, int c);
+ size_t strcspn(const char *s1, const char *s2);
+ char *strpbrk(const char *s1, const char *s2);
+ char *strrchr(const char *s, int c);
+ size_t strspn(const char *s1, const char *s2);
+ char *strstr(const char *s1, const char *s2);
+ char *strtok(char *s1, const char *s2);
+ void *memset(void *s, int c, size_t n);
+ char *strerror(int errnum);
+ size_t strlen(const char *s);
+</FONT></P></PRE><H4><A name="A.3.13">A.3.13 DATE AND TIME <time.h></A></H4>
+<PRE>
+<P class="code-block"><FONT size="+0"> CLK_TCK
+ NULL
+ clock_t
+ time_t
+ size_t
+ struct tm
+ clock_t clock(void);
+ double difftime(time_t time1, time_t time0);
+ time_t mktime(struct tm *timeptr);
+ time_t time(time_t *timer);
+ char *asctime(const struct tm *timeptr);
+ char *ctime(const time_t *timer);
+ struct tm *gmtime(const time_t *timer);
+ struct tm *localtime(const time_t *timer);
+ size_t strftime(char *s, size_t maxsize,
+ const char *format, const struct tm *timeptr);
+</FONT></P></PRE><H3><A name="A.4">A.4 IMPLEMENTATION LIMITS</A></H3>
+<P>
+<FONT size="-1"> The contents of a header <limits.h> are given below, in alphabetic
+order. The minimum magnitudes shown shall be replaced by
+implementation-defined magnitudes with the same sign. The values
+shall all be constant expressions suitable for use in #if
+preprocessing directives. The components are described further in
+<A href="
+ #2.2.4.2">2.2.4.2</A></FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define CHAR_BIT 8
+ #define CHAR_MAX UCHAR_MAX or SCHAR_MAX
+ #define CHAR_MIN 0 or SCHAR_MIN
+ #define MB_LEN_MAX 1
+ #define INT_MAX +32767
+ #define INT_MIN -32767
+ #define LONG_MAX +2147483647
+ #define LONG_MIN -2147483647
+ #define SCHAR_MAX +127
+ #define SCHAR_MIN -127
+ #define SHRT_MAX +32767
+ #define SHRT_MIN -32767
+ #define UCHAR_MAX 255
+ #define UINT_MAX 65535
+ #define ULONG_MAX 4294967295
+ #define USHRT_MAX 65535
+</FONT></P></PRE><P>
+<FONT size="-1"> The contents of a header <float.h> are given below, in alphabetic
+order. The value of FLT_RADIX shall be a constant expression suitable
+for use in #if preprocessing directives. Values that need not be
+constant expressions shall be supplied for all other components. The
+minimum magnitudes shown for integers and exponents shall be replaced
+by implementation-defined magnitudes with the same sign. The
+components are described further in <A href="
+ #2.2.4.2">2.2.4.2</A></FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> #define DBL_DIG 10
+ #define DBL_EPSILON 1E-9
+ #define DBL_MANT_DIG
+ #define DBL_MAX 1E+37
+ #define DBL_MAX_10_EXP +37
+ #define DBL_MAX_EXP
+ #define DBL_MIN 1E-37
+ #define DBL_MIN_10_EXP -37
+ #define DBL_MIN_EXP
+ #define FLT_DIG 6
+ #define FLT_EPSILON 1E-5
+ #define FLT_MANT_DIG
+ #define FLT_MAX 1E+37
+ #define FLT_MAX_10_EXP +37
+ #define FLT_MAX_EXP
+ #define FLT_MIN 1E-37
+ #define FLT_MIN_10_EXP -37
+ #define FLT_MIN_EXP
+ #define FLT_RADIX 2
+ #define FLT_ROUNDS
+ #define LDBL_DIG 10
+ #define LDBL_EPSILON 1E-9
+ #define LDBL_MANT_DIG
+ #define LDBL_MAX 1E+37
+ #define LDBL_MAX_10_EXP +37
+ #define LDBL_MAX_EXP
+ #define LDBL_MIN 1E-37
+ #define LDBL_MIN_10_EXP -37
+ #define LDBL_MIN_EXP
+</FONT></P></PRE><H3><A name="A.5">A.5 COMMON WARNINGS</A></H3>
+<P>
+<FONT size="-1"> An implementation may generate warnings in many situations, none of
+which is specified as part of the Standard. The following are a few
+of the more common situations.
+</FONT></P><P>
+<FONT size="-1"> * A block with initialization of an object that has automatic storage
+ duration is jumped into (<A href="
+ #3.1.2.4">3.1.2.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * An integer character constant includes more than one character or a
+ wide character constant includes more than one multibyte character
+ (<A href="
+ #3.1.3.4">3.1.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The characters /* are found in a comment (<A href="
+ #3.1.7">3.1.7</A>).
+</FONT></P><P>
+<FONT size="-1"> * An implicit narrowing conversion is encountered, such as the
+ assignment of a long int or a double to an int , or a pointer to void
+ to a pointer to any type of object other than char (<A href="
+ #3.2">3.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * An ``unordered'' binary operator (not comma, && or || ) contains a
+ side-effect to an lvalue in one operand, and a side-effect to, or an
+ access to the value of, the identical lvalue in the other operand
+ (<A href="
+ #3.3">3.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * A function is called but no prototype has been supplied (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The arguments in a function call do not agree in number and type
+ with those of the parameters in a function definition that is not a
+ prototype (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * An object is defined but not used (<A href="
+ #3.5">3.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * A value is given to an object of an enumeration type other than by
+ assignment of an enumeration constant that is a member of that type,
+ or an enumeration variable that has the same type, or the value of a
+ function that returns the same enumeration type (<A href="
+ #3.5.2.2">3.5.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * An aggregate has a partly bracketed initialization (<A href="
+ #3.5.7">3.5.7</A>).
+</FONT></P><P>
+<FONT size="-1"> * A statement cannot be reached (<A href="
+ #3.6">3.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * A statement with no apparent effect is encountered (<A href="
+ #3.6">3.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * A constant expression is used as the controlling expression of a
+ selection statement (<A href="
+ #3.6.4">3.6.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * A function has return statements with and without expressions (<A href="
+ #3.6.6.4">3.6.6.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * An incorrectly formed preprocessing group is encountered while
+ skipping a preprocessing group (<A href="
+ #3.8.1">3.8.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * An unrecognized #pragma directive is encountered (<A href="
+ #3.8.6">3.8.6</A>).
+</FONT></P><H3><A name="A.6">A.6 PORTABILITY ISSUES</A></H3>
+<P>
+<FONT size="-1"> This appendix collects some information about portability that
+appears in the Standard.
+</FONT></P><H4><A name="A.6.1">A.6.1 Unspecified behavior</A></H4>
+<P>
+<FONT size="-1"> The following are unspecified:
+</FONT></P><P>
+<FONT size="-1"> * The manner and timing of static initialization (<A href="
+ #2.1.2">2.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The behavior if a printable character is written when the active
+ position is at the final position of a line (<A href="
+ #2.2.2">2.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The behavior if a backspace character is written when the active
+ position is at the initial position of a line (<A href="
+ #2.2.2">2.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The behavior if a horizontal tab character is written when the
+ active position is at or past the last defined horizontal tabulation
+ position (<A href="
+ #2.2.2">2.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The behavior if a vertical tab character is written when the active
+ position is at or past the last defined vertical tabulation position
+ (<A href="
+ #2.2.2">2.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The representations of floating types (<A href="
+ #3.1.2.5">3.1.2.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * The order in which expressions are evaluated --- in any order
+ conforming to the precedence rules, even in the presence of
+ parentheses (<A href="
+ #3.3">3.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The order in which side effects take place (<A href="
+ #3.3">3.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The order in which the function designator and the arguments in a
+ function call are evaluated (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The alignment of the addressable storage unit allocated to hold a
+ bit-field (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The layout of storage for parameters (<A href="
+ #3.7.1">3.7.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The order in which # and ## operations are evaluated during macro
+ substitution (<A href="
+ #3.8.3.3">3.8.3.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether errno is a macro or an external identifier (<A href="
+ #4.1.3">4.1.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether setjmp is a macro or an external identifier (<A href="
+ #4.6.1.1">4.6.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether va_end is a macro or an external identifier (<A href="
+ #4.8.1.3">4.8.1.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value of the file position indicator after a successful call to
+ the ungetc function for a text stream, until all pushed-back
+ characters are read or discarded (<A href="
+ #4.9.7.11">4.9.7.11</A>).
+</FONT></P><P>
+<FONT size="-1"> * The details of the value stored by the fgetpos function on success
+ (<A href="
+ #4.9.9.1">4.9.9.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The details of the value returned by the ftell function for a text
+ stream on success (<A href="
+ #4.9.9.4">4.9.9.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The order and contiguity of storage allocated by the calloc ,
+ malloc , and realloc functions (<A href="
+ #4.10.3">4.10.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * Which of two members that compare as equal is returned by the
+ bsearch function (<A href="
+ #4.10.5.1">4.10.5.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The order in an array sorted by the qsort function of two members
+ that compare as equal (<A href="
+ #4.10.5.2">4.10.5.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The encoding of the calendar time returned by the time function
+ (<A href="
+ #4.12.2.3">4.12.2.3</A>).
+</FONT></P><H4><A name="A.6.2">A.6.2 Undefined behavior</A></H4>
+<P>
+<FONT size="-1"> The behavior in the following circumstances is undefined:
+</FONT></P><P>
+<FONT size="-1"> * A nonempty source file does not end in a new-line character, ends
+ in new-line character immediately preceded by a backslash character,
+ or ends in a partial preprocessing token or comment (<A href="
+ #2.1.1.2">2.1.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * A character not in the required character set is encountered in a
+ source file, except in a preprocessing token that is never converted
+ to a token, a character constant, a string literal, or a comment
+ (<A href="
+ #2.2.1">2.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * A comment, string literal, character constant, or header name
+ contains an invalid multibyte character or does not begin and end in
+ the initial shift state (<A href="
+ #2.2.1.2">2.2.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * An unmatched ' or character is encountered on a logical source line
+ during tokenization (<A href="
+ #3.1">3.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The same identifier is used more than once as a label in the same
+ function (<A href="
+ #3.1.2.1">3.1.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * An identifier is used that is not visible in the current scope (<A href="
+ #3.1.2.1">3.1.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * Identifiers that are intended to denote the same entity differ in a
+ character beyond the minimal significant characters (<A href="
+ #3.1.2">3.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The same identifier has both internal and external linkage in the
+ same translation unit (<A href="
+ #3.1.2.2">3.1.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * An identifier with external linkage is used but there does not
+ exist exactly one external definition in the program for the
+ identifier (<A href="
+ #3.1.2.2">3.1.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value stored in a pointer that referred to an object with
+ automatic storage duration is used (<A href="
+ #3.1.2.4">3.1.2.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * Two declarations of the same object or function specify types that
+ are not compatible (<A href="
+ #3.1.2.6">3.1.2.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * An unspecified escape sequence is encountered in a character
+ constant or a string literal (<A href="
+ #3.1.3.4">3.1.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * An attempt is made to modify a string literal of either form (<A href="
+ #3.1.4">3.1.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * A character string literal token is adjacent to a wide string
+ literal token (<A href="
+ #3.1.4">3.1.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The characters ', \ , , or /* are encountered between the < and >
+ delimiters or the characters ', \ , or /* are encountered between the
+ delimiters in the two forms of a header name preprocessing token
+ (<A href="
+ #3.1.7">3.1.7</A>).
+</FONT></P><P>
+<FONT size="-1"> * An arithmetic conversion produces a result that cannot be
+ represented in the space provided (<A href="
+ #3.2.1">3.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * An lvalue with an incomplete type is used in a context that
+ requires the value of the designated object (<A href="
+ #3.2.2.1">3.2.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value of a void expression is used or an implicit conversion
+ (except to void ) is applied to a void expression (<A href="
+ #3.2.2.2">3.2.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * An object is modified more than once, or is modified and accessed
+ other than to determine the new value, between two sequence points
+ (<A href="
+ #3.3">3.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * An arithmetic operation is invalid (such as division or modulus by 0)
+ or produces a result that cannot be represented in the space
+ provided (such as overflow or underflow) (<A href="
+ #3.3">3.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * An object has its stored value accessed by an lvalue that does not
+ have one of the following types: the declared type of the object, a
+ qualified version of the declared type of the object, the signed or
+ unsigned type corresponding to the declared type of the object, the
+ signed or unsigned type corresponding to a qualified version of the
+ declared type of the object, an aggregate or union type that
+ (recursively) includes one of the aforementioned types among its
+ members, or a character type (<A href="
+ #3.3">3.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * An argument to a function is a void expression (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * For a function call without a function prototype, the number of
+ arguments does not agree with the number of parameters (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * For a function call without a function prototype, if the function
+ is defined without a function prototype, and the types of the
+ arguments after promotion do not agree with those of the parameters
+ after promotion (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * If a function is called with a function prototype and the function
+ is not defined with a compatible type (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * A function that accepts a variable number of arguments is called
+ without a function prototype that ends with an ellipsis (<A href="
+ #3.3.2.2">3.3.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * An invalid array reference, null pointer reference, or reference to
+ an object declared with automatic storage duration in a terminated
+ block occurs (<A href="
+ #3.3.3.2">3.3.3.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * A pointer to a function is converted to point to a function of a
+ different type and used to call a function of a type not compatible
+ with the original type (<A href="
+ #3.3.4">3.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * A pointer to a function is converted to a pointer to an object or a
+ pointer to an object is converted to a pointer to a function (<A href="
+ #3.3.4">3.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * A pointer is converted to other than an integral or pointer type (<A href="
+ #3.3.4">3.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * A pointer that is not to a member of an array object is added to or
+ subtracted from (<A href="
+ #3.3.6">3.3.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * Pointers that are not to the same array object are subtracted (<A href="
+ #3.3.6">3.3.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * An expression is shifted by a negative number or by an amount
+ greater than or equal to the width in bits of the expression being
+ shifted (<A href="
+ #3.3.7">3.3.7</A>).
+</FONT></P><P>
+<FONT size="-1"> * Pointers are compared using a relational operator that do not point
+ to the same aggregate or union (<A href="
+ #3.3.8">3.3.8</A>).
+</FONT></P><P>
+<FONT size="-1"> * An object is assigned to an overlapping object (<A href="
+ #3.3.16.1">3.3.16.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * An identifier for an object is declared with no linkage and the
+ type of the object is incomplete after its declarator, or after its
+ init-declarator if it has an initializer (<A href="
+ #3.5">3.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * A function is declared at block scope with a storage-class
+ specifier other than extern (<A href="
+ #3.5.1">3.5.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * A bit-field is declared with a type other than int , signed int ,
+ or unsigned int (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * An attempt is made to modify an object with const-qualified type by
+ means of an lvalue with non-const-qualified type (<A href="
+ #3.5.3">3.5.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * An attempt is made to refer to an object with volatile-qualified
+ type by means of an lvalue with non-volatile-qualified type (<A href="
+ #3.5.3">3.5.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value of an uninitialized object that has automatic storage
+ duration is used before a value is assigned (<A href="
+ #3.5.7">3.5.7</A>).
+</FONT></P><P>
+<FONT size="-1"> * An object with aggregate or union type with static storage duration
+ has a non-brace-enclosed initializer, or an object with aggregate or
+ union type with automatic storage duration has either a single
+ expression initializer with a type other than that of the object or a
+ non-brace-enclosed initializer (<A href="
+ #3.5.7">3.5.7</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value of a function is used, but no value was returned (<A href="
+ #3.6.6.4">3.6.6.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * A function that accepts a variable number of arguments is defined
+ without a parameter type list that ends with the ellipsis notation
+ (<A href="
+ #3.7.1">3.7.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * An identifier for an object with internal linkage and an incomplete
+ type is declared with a tentative definition (<A href="
+ #3.7.2">3.7.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The token defined is generated during the expansion of a #if or
+ #elif preprocessing directive (<A href="
+ #3.8.1">3.8.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The #include preprocessing directive that results after expansion
+ does not match one of the two header name forms (<A href="
+ #3.8.2">3.8.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * A macro argument consists of no preprocessing tokens (<A href="
+ #3.8.3">3.8.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * There are sequences of preprocessing tokens within the list of
+ macro arguments that would otherwise act as preprocessing directive
+ lines (<A href="
+ #3.8.3">3.8.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The result of the preprocessing concatenation operator ## is not a
+ valid preprocessing token (<A href="
+ #3.8.3">3.8.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The #line preprocessing directive that results after expansion does
+ not match one of the two well-defined forms (<A href="
+ #3.8.4">3.8.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * One of the following identifiers is the subject of a #define or
+ #undef preprocessing directive: defined , __LINE__ , __FILE__ ,
+ __DATE__ , __TIME__ , or __STDC__ (<A href="
+ #3.8.8">3.8.8</A>).
+</FONT></P><P>
+<FONT size="-1"> * An attempt is made to copy an object to an overlapping object by
+ use of a library function other than memmove (<A href="
+ #4.">4.</A>).
+</FONT></P><P>
+<FONT size="-1"> * The effect if the program redefines a reserved external identifier
+ (<A href="
+ #4.1.2">4.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The effect if a standard header is included within an external
+ definition; is included for the first time after the first reference
+ to any of the functions or objects it declares, or to any of the types
+ or macros it defines; or is included while a macro is defined with a
+ name the same as a keyword (<A href="
+ #4.1.2">4.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * A macro definition of errno is suppressed to obtain access to an
+ actual object (<A href="
+ #4.1.3">4.1.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The parameter member-designator of an offsetof macro is an invalid
+ right operand of the . operator for the type parameter or designates
+ bit-field member of a structure (<A href="
+ #4.1.5">4.1.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * A library function argument has an invalid value, unless the
+ behavior is specified explicitly (<A href="
+ #4.1.6">4.1.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * A library function that accepts a variable number of arguments is
+ not declared (<A href="
+ #4.1.6">4.1.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * The macro definition of assert is suppressed to obtain access to an
+ actual function (<A href="
+ #4.2">4.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The argument to a character handling function is out of the domain (<A href="
+ #4.3">4.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * A macro definition of setjmp is suppressed to obtain access to an
+ actual function (<A href="
+ #4.6">4.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * An invocation of the setjmp macro occurs in a context other than as
+ the controlling expression in a selection or iteration statement, or
+ in a comparison with an integral constant expression (possibly as
+ implied by the unary ! operator) as the controlling expression of a
+ selection or iteration statement, or as an expression statement
+ (possibly cast to void ) (<A href="
+ #4.6.1.1">4.6.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * An object of automatic storage class that does not have
+ volatile-qualified type has been changed between a setjmp invocation
+ and a longjmp call and then has its value accessed (<A href="
+ #4.6.2.1">4.6.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The longjmp function is invoked from a nested signal routine (<A href="
+ #4.6.2.1">4.6.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * A signal occurs other than as the result of calling the abort or
+ raise function, and the signal handler calls any function in the
+ standard library other than the signal function itself or refers to
+ any object with static storage duration other than by assigning a
+ value to a static storage duration variable of type volatile
+ sig_atomic_t (<A href="
+ #4.7.1.1">4.7.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value of errno is referred to after a signal occurs other than
+ as the result of calling the abort or raise function and the
+ corresponding signal handler calls the signal function such that it
+ returns the value SIG_ERR (<A href="
+ #4.7.1.1">4.7.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The macro va_arg is invoked with the parameter ap that was passed
+ to a function that invoked the macro va_arg with the same parameter
+ (<A href="
+ #4.8">4.8</A>).
+</FONT></P><P>
+<FONT size="-1"> * A macro definition of va_start , va_arg , or va_end or a
+ combination thereof is suppressed to obtain access to an actual
+ function (<A href="
+ #4.8.1">4.8.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The parameter parmN of a va_start macro is declared with the
+ register storage class, or with a function or array type, or with a
+ type that is not compatible with the type that results after
+ application of the default argument promotions (<A href="
+ #4.8.1.1">4.8.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * There is no actual next argument for a va_arg macro invocation
+ (<A href="
+ #4.8.1.2">4.8.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The type of the actual next argument in a variable argument list
+ disagrees with the type specified by the va_arg macro (<A href="
+ #4.8.1.2">4.8.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The va_end macro is invoked without a corresponding invocation of
+ the va_start macro (<A href="
+ #4.8.1.3">4.8.1.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * A return occurs from a function with a variable argument list
+ initialized by the va_start macro before the va_end macro is invoked
+ (<A href="
+ #4.8.1.3">4.8.1.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The stream for the fflush function points to an input stream or to
+ an update stream in which the most recent operation was input
+ (<A href="
+ #4.9.5.2">4.9.5.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * An output operation on an update stream is followed by an input
+ operation without an intervening call to the fflush function or a file
+ positioning function, or an input operation on an update stream is
+ followed by an output operation without an intervening call to a file
+ positioning function (<A href="
+ #4.9.5.3">4.9.5.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The format for the fprintf or fscanf function does not match the
+ argument list (<A href="
+ #4.9.6">4.9.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * An invalid conversion specification is found in the format for the
+ fprintf or fscanf function (<A href="
+ #4.9.6">4.9.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * A %% conversion specification for the fprintf or fscanf function
+ contains characters between the pair of % characters (<A href="
+ #4.9.6">4.9.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * A conversion specification for the fprintf function contains an h
+ or l with a conversion specifier other than d , i , n , o , u , x , or
+ X , or an L with a conversion specifier other than e , E , f , g , or
+ G (<A href="
+ #4.9.6.1">4.9.6.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * A conversion specification for the fprintf function contains a #
+ flag with a conversion specifier other than o , x , X , e , E , f , g,
+ or G (<A href="
+ #4.9.6.1">4.9.6.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * A conversion specification for the fprintf function contains a 0
+ flag with a conversion specifier other than d , i , o , u , x , X , e,
+ E , f , g , or G (<A href="
+ #4.9.6.1">4.9.6.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * An aggregate or union, or a pointer to an aggregate or union is an
+ argument to the fprintf function, except for the conversion specifiers
+ %s (for an array of character type) or %p (for a pointer to void )
+ (<A href="
+ #4.9.6.1">4.9.6.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * A single conversion by the fprintf function produces more than 509
+ characters of output (<A href="
+ #4.9.6.1">4.9.6.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * A conversion specification for the fscanf function contains an h or
+ l with a conversion specifier other than d , i , n , o , u , or x , or
+ an L with a conversion specifier other than e , f , or g (<A href="
+ #4.9.6.2">4.9.6.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * A pointer value printed by %p conversion by the fprintf function
+ during a previous program execution is the argument for %p conversion
+ by the fscanf function (<A href="
+ #4.9.6.2">4.9.6.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The result of a conversion by the fscanf function cannot be
+ represented in the space provided, or the receiving object does not
+ have an appropriate type (<A href="
+ #4.9.6.2">4.9.6.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The result of converting a string to a number by the atof , atoi ,
+ or atol function cannot be represented (<A href="
+ #4.10.1">4.10.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value of a pointer that refers to space deallocated by a call
+ to the free or realloc function is referred to (<A href="
+ #4.10.3">4.10.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The pointer argument to the free or realloc function does not match
+ a pointer earlier returned by calloc , malloc , or realloc , or the
+ object pointed to has been deallocated by a call to free or realloc
+ (<A href="
+ #4.10.3">4.10.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * A program executes more than one call to the exit function (<A href="
+ #4.10.4.3">4.10.4.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The result of an integer arithmetic function ( abs , div , labs ,
+ or ldiv ) cannot be represented (<A href="
+ #4.10.6">4.10.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * The shift states for the mblen , mbtowc , and wctomb functions are
+ not explicitly reset to the initial state when the LC_CTYPE category
+ of the current locale is changed (<A href="
+ #4.10.7">4.10.7</A>).
+</FONT></P><P>
+<FONT size="-1"> * An array written to by a copying or concatenation function is too
+ small (<A href="
+ #4.11.2">4.11.2</A>, <A href="
+ #4.11.3">4.11.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * An invalid conversion specification is found in the format for the
+ strftime function (<A href="
+ #4.12.3.5">4.12.3.5</A>).
+</FONT></P><H4><A name="A.6.3">A.6.3 Implementation-defined behavior</A></H4>
+<P>
+<FONT size="-1"> Each implementation shall document its behavior in each of the
+areas listed in this section. The following are
+implementation-defined:
+</FONT></P><H5><A name="A.6.3.1">A.6.3.1 Environment</A></H5>
+<P>
+<FONT size="-1"> * The semantics of the arguments to main (<A href="
+ #2.1.2.2">2.1.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * What constitutes an interactive device (<A href="
+ #2.1.2.3">2.1.2.3</A>).
+</FONT></P><H5><A name="A.6.3.2">A.6.3.2 Identifiers</A></H5>
+<P>
+<FONT size="-1"> * The number of significant initial characters (beyond 31) in an
+ identifier without external linkage (<A href="
+ #3.1.2">3.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The number of significant initial characters (beyond 6) in an
+ identifier with external linkage (<A href="
+ #3.1.2">3.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether case distinctions are significant in an identifier with
+ external linkage (<A href="
+ #3.1.2">3.1.2</A>).
+</FONT></P><H5><A name="A.6.3.3">A.6.3.3 Characters</A></H5>
+<P>
+<FONT size="-1"> * The members of the source and execution character sets, except as
+ explicitly specified in the Standard (<A href="
+ #2.2.1">2.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The shift states used for the encoding of multibyte characters <A href="
+ #2.2.1.2">2.2.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The number of bits in a character in the execution character set
+ (<A href="
+ #2.2.4.2">2.2.4.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The mapping of members of the source character set (in character
+ constants and string literals) to members of the execution character
+ set (<A href="
+ #3.1.3.4">3.1.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value of an integer character constant that contains a
+ character or escape sequence not represented in the basic execution
+ character set or the extended character set for a wide character
+ constant (<A href="
+ #3.1.3.4">3.1.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value of an integer character constant that contains more than
+ one character or a wide character constant that contains more than one
+ multibyte character (<A href="
+ #3.1.3.4">3.1.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The current locale used to convert multibyte characters into
+ corresponding wide characters (codes) for a wide character constant
+ (<A href="
+ #3.1.3.4">3.1.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether a ``plain'' char has the same range of values as signed
+ char or unsigned char (<A href="
+ #3.2.1.1">3.2.1.1</A>).
+</FONT></P><H5><A name="A.6.3.4">A.6.3.4 Integers</A></H5>
+<P>
+<FONT size="-1"> * The representations and sets of values of the various types of
+ integers (<A href="
+ #3.1.2.5">3.1.2.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * The result of converting an integer to a shorter signed integer, or
+ the result of converting an unsigned integer to a signed integer of
+ equal length, if the value cannot be represented (<A href="
+ #3.2.1.2">3.2.1.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The results of bitwise operations on signed integers (<A href="
+ #3.3">3.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The sign of the remainder on integer division (<A href="
+ #3.3.5">3.3.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * The result of a right shift of a negative-valued signed integral
+ type (<A href="
+ #3.3.7">3.3.7</A>).
+</FONT></P><H5><A name="A.6.3.5">A.6.3.5 Floating point</A></H5>
+<P>
+<FONT size="-1"> * The representations and sets of values of the various types of
+ floating-point numbers (<A href="
+ #3.1.2.5">3.1.2.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * The direction of truncation when an integral number is converted to
+ a floating-point number that cannot exactly represent the original
+ value (<A href="
+ #3.2.1.3">3.2.1.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The direction of truncation or rounding when a floating-point
+ number is converted to a narrower floating-point number (<A href="
+ #3.2.1.4">3.2.1.4</A>).
+</FONT></P><H5><A name="A.6.3.6">A.6.3.6 Arrays and pointers</A></H5>
+<P>
+<FONT size="-1"> * The type of integer required to hold the maximum size of an array
+ --- that is, the type of the sizeof operator, size_t (<A href="
+ #3.3.3.4">3.3.3.4</A>,
+ <A href="
+ #4.1.1">4.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The result of casting a pointer to an integer or vice versa (<A href="
+ #3.3.4">3.3.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The type of integer required to hold the difference between two
+ pointers to members of the same array, ptrdiff_t (<A href="
+ #3.3.6">3.3.6</A>, <A href="
+ #4.1.1">4.1.1</A>).
+</FONT></P><H5><A name="A.6.3.7">A.6.3.7 Registers</A></H5>
+<P>
+<FONT size="-1"> * The extent to which objects can actually be placed in registers by
+ use of the register storage-class specifier (<A href="
+ #3.5.1">3.5.1</A>).
+</FONT></P><H5><A name="A.6.3.8">A.6.3.8 Structures, unions, enumerations, and bit-fields</A></H5>
+<P>
+<FONT size="-1"> * A member of a union object is accessed using a member of a
+ different type (<A href="
+ #3.3.2.3">3.3.2.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The padding and alignment of members of structures (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+ This should present no problem unless binary data written by one
+ implementation are read by another.
+</FONT></P><P>
+<FONT size="-1"> * Whether a ``plain'' int bit-field is treated as a signed int
+ bit-field or as an unsigned int bit-field (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The order of allocation of bit-fields within an int (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether a bit-field can straddle a storage-unit boundary (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The integer type chosen to represent the values of an enumeration
+ type (<A href="
+ #3.5.2.2">3.5.2.2</A>).
+</FONT></P><H5><A name="A.6.3.9">A.6.3.9 Qualifiers</A></H5>
+<P>
+<FONT size="-1"> * What constitutes an access to an object that has volatile-qualified
+ type (<A href="
+ #3.5.5.3">3.5.5.3</A>).
+</FONT></P><H5><A name="A.6.3.10">A.6.3.10 Declarators</A></H5>
+<P>
+<FONT size="-1"> * The maximum number of declarators that may modify an arithmetic,
+ structure, or union type (<A href="
+ #3.5.4">3.5.4</A>).
+</FONT></P><H5><A name="A.6.3.11">A.6.3.11 Statements</A></H5>
+<P>
+<FONT size="-1"> * The maximum number of case values in a switch statement (<A href="
+ #3.6.4.2">3.6.4.2</A>).
+</FONT></P><H5><A name="A.6.3.12">A.6.3.12 Preprocessing directives</A></H5>
+<P>
+<FONT size="-1"> * Whether the value of a single-character character constant in a
+ constant expression that controls conditional inclusion matches the
+ value of the same character constant in the execution character set.
+ Whether such a character constant may have a negative value (<A href="
+ #3.8.1">3.8.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The method for locating includable source files (<A href="
+ #3.8.2">3.8.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The support of quoted names for includable source files (<A href="
+ #3.8.2">3.8.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The mapping of source file character sequences (<A href="
+ #3.8.2">3.8.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The behavior on each recognized #pragma directive (<A href="
+ #3.8.6">3.8.6</A>).
+</FONT></P><P>
+<FONT size="-1"> * The definitions for __DATE__ and __TIME__ when respectively, the
+ date and time of translation are not available (<A href="
+ #3.8.8">3.8.8</A>).
+</FONT></P><H5><A name="A.6.3.13">A.6.3.13 Library functions</A></H5>
+<P>
+<FONT size="-1"> * The null pointer constant to which the macro NULL expands (<A href="
+ #4.1.5">4.1.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * The diagnostic printed by and the termination behavior of the
+ assert function (<A href="
+ #4.2">4.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The sets of characters tested for by the isalnum , isalpha ,
+ iscntrl , islower , isprint , and isupper functions (<A href="
+ #4.3.1">4.3.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The values returned by the mathematics functions on domain errors
+ (<A href="
+ #4.5.1">4.5.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether the mathematics functions set the integer expression errno
+ to the value of the macro ERANGE on underflow range errors (<A href="
+ #4.5.1">4.5.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether a domain error occurs or zero is returned when the fmod
+ function has a second argument of zero (<A href="
+ #4.5.6.4">4.5.6.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The set of signals for the signal function (<A href="
+ #4.7.1.1">4.7.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The semantics for each signal recognized by the signal function
+ (<A href="
+ #4.7.1.1">4.7.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The default handling and the handling at program startup for each
+ signal recognized by the signal function (<A href="
+ #4.7.1.1">4.7.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * If the equivalent of signal(sig, SIG_DFL); is not executed prior to
+ the call of a signal handler, the blocking of the signal that is
+ performed (<A href="
+ #4.7.1.1">4.7.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether the default handling is reset if the SIGILL signal is
+ received by a handler specified to the signal function (<A href="
+ #4.7.1.1">4.7.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether the last line of a text stream requires a terminating
+ new-line character (<A href="
+ #4.9.2">4.9.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether space characters that are written out to a text stream
+ immediately before a new-line character appear when read in (<A href="
+ #4.9.2">4.9.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The number of null characters that may be appended to data written
+ to a binary stream (<A href="
+ #4.9.2">4.9.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether the file position indicator of an append mode stream is
+ initially positioned at the beginning or end of the file (<A href="
+ #4.9.3">4.9.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether a write on a text stream causes the associated file to be
+ truncated beyond that point (<A href="
+ #4.9.3">4.9.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The characteristics of file buffering (<A href="
+ #4.9.3">4.9.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether a zero-length file actually exists (<A href="
+ #4.9.3">4.9.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The rules for composing valid file names (<A href="
+ #4.9.3">4.9.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * Whether the same file can be open multiple times (<A href="
+ #4.9.3">4.9.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The effect of the remove function on an open file (<A href="
+ #4.9.4.1">4.9.4.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The effect if a file with the new name exists prior to a call to
+ the rename function (<A href="
+ #4.9.4.2">4.9.4.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The output for %p conversion in the fprintf function (<A href="
+ #4.9.6.1">4.9.6.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The input for %p conversion in the fscanf function (<A href="
+ #4.9.6.2">4.9.6.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The interpretation of a - character that is neither the first nor
+ the last character in the scanlist for %[ conversion in the fscanf
+ function (<A href="
+ #4.9.6.2">4.9.6.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The value to which the macro errno is set by the fgetpos or ftell
+ function on failure (<A href="
+ #4.9.9.1">4.9.9.1</A>, <A href="
+ #4.9.9.4">4.9.9.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The messages generated by the perror function (<A href="
+ #4.9.10.4">4.9.10.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The behavior of the calloc , malloc , or realloc function if the
+ size requested is zero (<A href="
+ #4.10.3">4.10.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The behavior of the abort function with regard to open and
+ temporary files (<A href="
+ #4.10.4.1">4.10.4.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The status returned by the exit function if the value of the
+ argument is other than zero, EXIT_SUCCESS , or EXIT_FAILURE
+ (<A href="
+ #4.10.4.3">4.10.4.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The set of environment names and the method for altering the
+ environment list used by the getenv function (<A href="
+ #4.10.4.4">4.10.4.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The contents and mode of execution of the string by the system
+ function (<A href="
+ #4.10.4.5">4.10.4.5</A>).
+</FONT></P><P>
+<FONT size="-1"> * The contents of the error message strings returned by the strerror
+ function (<A href="
+ #4.11.6.2">4.11.6.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The local time zone and Daylight Saving Time (<A href="
+ #4.12.1">4.12.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The era for the clock function (<A href="
+ #4.12.2.1">4.12.2.1</A>).
+</FONT></P><H4><A name="A.6.4">A.6.4 Locale-specific Behavior</A></H4>
+<P>
+<FONT size="-1"> The following characteristics of a hosted environment are locale-specific:
+</FONT></P><P>
+<FONT size="-1"> * The content of the execution character set, in addition to the
+ required members (<A href="
+ #2.2.1">2.2.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The direction of printing (<A href="
+ #2.2.2">2.2.2</A>).
+</FONT></P><P>
+<FONT size="-1"> * The decimal-point character (<A href="
+ #4.1.1">4.1.1</A>).
+</FONT></P><P>
+<FONT size="-1"> * The implementation-defined aspects of character testing and case
+ mapping functions (<A href="
+ #4.3">4.3</A>).
+</FONT></P><P>
+<FONT size="-1"> * The collation sequence of the execution character set (<A href="
+ #4.11.4.4">4.11.4.4</A>).
+</FONT></P><P>
+<FONT size="-1"> * The formats for time and date (<A href="
+ #4.12.3.5">4.12.3.5</A>).
+</FONT></P><H4><A name="A.6.5">A.6.5 Common extensions</A></H4>
+<P>
+<FONT size="-1"> The following extensions are widely used in many systems, but are
+not portable to all implementations. The inclusion of any extension
+that may cause a strictly conforming program to become invalid renders
+an implementation nonconforming. Examples of such extensions are new
+keywords, or library functions declared in standard headers or
+predefined macros with names that do not begin with an underscore.
+</FONT></P><H5><A name="A.6.5.1">A.6.5.1 Environment arguments</A></H5>
+<P>
+<FONT size="-1"> In a hosted environment, the main function receives a third
+argument, char *envp[] , that points to a null-terminated array of
+pointers to char , each of which points to a string that provides
+information about the environment for this execution of the process
+(<A href="
+ #2.1.2.2">2.1.2.2</A>).
+</FONT></P><H5><A name="A.6.5.2">A.6.5.2 Specialized identifiers</A></H5>
+<P>
+<FONT size="-1"> Characters other than the underscore _ , letters, and digits, that
+are not defined in the required source character set (such as the
+dollar sign $ , or characters in national character sets) may appear
+in an identifier (<A href="
+ #3.1.2">3.1.2</A>).
+</FONT></P><H5><A name="A.6.5.3">A.6.5.3 Lengths and cases of identifiers</A></H5>
+<P>
+<FONT size="-1"> All characters in identifiers (with or without external linkage)
+are significant and case distinctions are observed (<A href="
+ #3.1.2">3.1.2</A>).
+</FONT></P><H5><A name="A.6.5.4">A.6.5.4 Scopes of identifiers</A></H5>
+<P>
+<FONT size="-1"> A function identifier, or the identifier of an object the
+declaration of which contains the keyword extern , has file scope
+(<A href="
+ #3.1.2.1">3.1.2.1</A>).
+</FONT></P><H5><A name="A.6.5.5">A.6.5.5 Writable string literals</A></H5>
+<P>
+<FONT size="-1"> String literals are modifiable. Identical string literals shall be
+distinct (<A href="
+ #3.1.4">3.1.4</A>).
+</FONT></P><H5><A name="A.6.5.6">A.6.5.6 Other arithmetic types</A></H5>
+<P>
+<FONT size="-1"> Other arithmetic types, such as long long int , and their
+appropriate conversions are defined (<A href="
+ #3.2.2.1">3.2.2.1</A>).
+</FONT></P><H5><A name="A.6.5.7">A.6.5.7 Function pointer casts</A></H5>
+<P>
+<FONT size="-1"> A pointer to an object or to void may be cast to a pointer to a
+function, allowing data to be invoked as a function (<A href="
+ #3.3.4">3.3.4</A>). A
+pointer to a function may be cast to a pointer to an object or to void
+, allowing a function to be inspected or modified (for example, by a
+debugger) (<A href="
+ #3.3.4">3.3.4</A>).
+</FONT></P><H5><A name="A.6.5.8">A.6.5.8 Non-int bit-field types</A></H5>
+<P>
+<FONT size="-1"> Types other than int , unsigned int , or signed int can be declared
+as bit-fields, with appropriate maximum widths (<A href="
+ #3.5.2.1">3.5.2.1</A>).
+</FONT></P><H5><A name="A.6.5.9">A.6.5.9 The fortran keyword</A></H5>
+<P>
+<FONT size="-1"> The fortran type specifier may be used in a function declaration to
+indicate that function linkage suitable for FORTRAN is to be
+generated, or that different representations for external names are to
+be generated (<A href="
+ #3.5.4.3">3.5.4.3</A>).
+</FONT></P><H5><A name="A.6.5.10">A.6.5.10 The asm keyword</A></H5>
+<P>
+<FONT size="-1"> The asm keyword may be used to insert assembly-language code
+directly into the translator output. The most common implementation
+is via a statement of the form
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> asm ( character-string-literal );
+</FONT></P></PRE><P>
+<FONT size="-1">(<A href="
+ #3.6">3.6</A>).
+</FONT></P><H5><A name="A.6.5.11">A.6.5.11 Multiple external definitions</A></H5>
+<P>
+<FONT size="-1"> There may be more than one external definition for the identifier
+of an object, with or without the explicit use of the keyword extern ,
+If the definitions disagree, or more than one is initialized, the
+behavior is undefined (<A href="
+ #3.7.2">3.7.2</A>).
+</FONT></P><H5><A name="A.6.5.12">A.6.5.12 Empty macro arguments</A></H5>
+<P>
+<FONT size="-1"> A macro argument may consist of no preprocessing tokens (<A href="
+ #3.8.3">3.8.3</A>).
+</FONT></P><H5><A name="A.6.5.13">A.6.5.13 Predefined macro names</A></H5>
+<P>
+<FONT size="-1"> Macro names that do not begin with an underscore, describing the
+translation and execution environments, may be defined by the
+implementation before translation begins (<A href="
+ #3.8.8">3.8.8</A>).
+</FONT></P><H5><A name="A.6.5.14">A.6.5.14 Extra arguments for signal handlers</A></H5>
+<P>
+<FONT size="-1"> Handlers for specific signals may be called with extra arguments in
+addition to the signal number (<A href="
+ #4.7.1.1">4.7.1.1</A>).
+</FONT></P><H5><A name="A.6.5.15">A.6.5.15 Additional stream types and file-opening modes</A></H5>
+<P>
+<FONT size="-1"> Additional mappings from files to streams may be supported
+(<A href="
+ #4.9.2">4.9.2</A>), and additional file-opening modes may be specified by
+characters appended to the mode argument of the fopen function
+(<A href="
+ #4.9.5.3">4.9.5.3</A>).
+</FONT></P><H5><A name="A.6.5.16">A.6.5.16 Defined file position indicator</A></H5>
+<P>
+<FONT size="-1"> The file position indicator is decremented by each successful call
+to the ungetc function for a text stream, except if its value was zero
+before a call (<A href="
+ #4.9.7.11">4.9.7.11</A>).
+</FONT></P><H3><A name="A.7">A.7 INDEX</A></H3>
+<P>
+<FONT size="-1"> Only major references are listed.
+</FONT></P><P>
+<FONT size="-1">absolute-value functions, 4.5.6.2, 4.10.6.1
+abstract declarator, type name, 3.5.5
+abstract machine, 2.1.2.3
+abstract semantics, 2.1.2.3
+active position, 2.2.2
+addition assignment operator, +=, 3.3.16.2
+addition operator, +, 3.3.6
+additive expressions, 3.3.6
+address operator, &, 3.3.3.2
+aggregate type, 3.1.2.5
+alert escape sequence, \a, 2.2.2, 3.1.3.4
+alignment, definition of, 1.6
+alignment of structure members, 3.5.2.1
+AND operator, bitwise, &, 3.3.10
+AND operator, logical, &&, 3.3.13
+argument, function, 3.3.2.2
+argument, 1.6
+argument promotion, default, 3.3.2.2
+arithmetic conversions, usual, 3.2.1.5
+arithmetic operators, unary, 3.3.3.3
+arithmetic type, 3.1.2.5
+array declarator, 3.5.4.2
+array parameter, 3.7.1
+array subscript operator, [ ], 3.3.2.1
+array type, 3.1.2.5
+array type conversion, 3.2.2.1
+arrow operator, ->, 3.3.2.3
+ASCII character set, 2.2.1.1
+assignment operators, 3.3.16
+asterisk punctuator, *, 3.1.6, 3.5.4.1
+automatic storage, reentrancy, 2.1.2.3, 2.2.3
+automatic storage duration, 3.1.2.4
+</FONT></P><P>
+<FONT size="-1">backslash character, \, 2.1.1.2, 2.2.1
+backspace escape sequence, \b, 2.2.2, 3.1.3.4
+base documents, 1.5
+basic character set, 1.6, 2.2.1
+basic type, 3.1.2.5
+binary stream, 4.9.2
+bit, definition of, 1.6
+bit, high-order, 1.6
+bit, low-order, 1.6
+bit-field structure member, 3.5.2.1
+bitwise operators, 3.3, 3.3.7, 3.3.10, 3.3.11, 3.3.12
+block, 3.6.2
+block identifier scope, 3.1.2.1
+braces punctuator, { }, 3.1.6, 3.5.7, 3.6.2
+brackets punctuator, [ ], 3.1.6, 3.3.2.1, 3.5.4.2
+broken-down-time type, 4.12.1
+byte, definition of, 1.6
+</FONT></P><P>
+<FONT size="-1">C program, 2.1.1.1
+C Standard, definition of terms, 1.6
+C Standard, organization of document, 1.4
+C Standard, purpose of, 1.1
+C Standard, references, 1.3
+C Standard, scope, restrictions and limits, 1.2
+carriage-return escape sequence, \r, 2.2.2, 3.1.3.4
+case mapping functions, 4.3.2
+cast expressions, 3.3.4
+cast operator, ( ), 3.3.4
+character, 1.6
+character case mapping functions, 4.3.2
+character constant, 2.1.1.2, 2.2.1, 3.1.3.4
+character display semantics, 2.2.2
+character handling header, 4.3
+character input/output functions, 4.9.7
+character sets, 2.2.1
+character string literal, 2.1.1.2, 3.1.4
+character testing functions, 4.3.1
+character type, 3.1.2.5, 3.2.2.1, 3.5.7
+character type conversion, 3.2.1.1
+collating sequence, character set, 2.2.1
+colon punctuator, :, 3.1.6, 3.5.2.1
+comma operator, ,, 3.3.17
+command processor, 4.10.4.5
+comment delimiters, /* */, 3.1.9
+comments, 2.1.1.2, 3.1, 3.1.9
+common initial sequence, 3.3.2.3
+comparison functions, 4.11.4
+compatible type, 3.1.2.6, 3.5.2, 3.5.3, 3.5.4
+complement operator, ~, 3.3.3.3
+compliance, 1.7
+composite type, 3.1.2.6
+compound assignment operators, 3.3.16.2
+compound statement, 3.6.2
+concatenation functions, 4.11.3
+conceptual models, 2.1
+conditional inclusion, 3.8.1
+conditional operator, ? :, 3.3.15
+conforming freestanding implementation, 1.7
+conforming hosted implementation, 1.7
+conforming implementation, 1.7
+conforming program, 1.7
+const-qualified type, 3.1.2.5, 3.2.2.1, 3.5.3
+constant, character, 3.1.3.4
+constant, enumeration, 3.1.2, 3.1.3.3
+constant, floating, 3.1.3.1
+constant, integer, 3.1.3.2
+constant, primary expression, 3.3.1
+constant expressions, 3.4
+constants, 3.1.3
+constraints, definition of, 1.6
+content, structure/union/enumeration, 3.5.2.3
+contiguity, memory allocation, 4.10.3
+control characters, 2.2.1, 4.3.1, 4.3.1.3
+conversion, arithmetic operands, 3.2.1
+conversion, array, 3.2.2.1
+conversion, characters and integers, 3.2.1.1
+conversion, explicit, 3.2
+conversion, floating and integral, 3.2.1.3
+conversion, floating types, 3.2.1.4, 3.2.1.5
+conversion, function, 3.2.2.1
+conversion, function arguments, 3.3.2.2, 3.7.1
+conversion, implicit, 3.2
+conversion, pointer, 3.2.2.1, 3.2.2.3
+conversion, signed and unsigned integers, 3.2.1.2
+conversion, void type, 3.2.2.2
+conversions, 3.2
+conversions, usual arithmetic, 3.2.1.5
+copying functions, 4.11.2
+</FONT></P><P>
+<FONT size="-1">data streams, 4.9.2
+date and time header, 4.12
+decimal constant, 3.1.3.2
+decimal digits, 2.2.1
+decimal-point character, 4.1.1
+declaration specifiers, 3.5
+declarations, 3.5
+declarators, 3.5.4
+declarator type derivation, 3.1.2.5, 3.5.4
+decrement operator, postfix, --, 3.3.2.4
+decrement operator, prefix, --, 3.3.3.1
+default argument promotions, 3.3.2.2
+definition, 3.5
+derived declarator types, 3.1.2.5
+derived types, 3.1.2.5
+device input/output, 2.1.2.3
+diagnostics, 2.1.1.3
+diagnostics, assert.h, 4.2
+direct input/output functions, 4.9.8
+display device, 2.2.2
+division assignment operator, /=, 3.3.16.2
+division operator, /, 3.3.5
+documentation of implementation, 1.7
+domain error, 4.5.1
+dot operator, ., 3.3.2.3
+double-precision arithmetic, 2.1.2.3
+</FONT></P><P>
+<FONT size="-1">element type, 3.1.2.5
+ellipsis, unspecified parameters, , ..., 3.5.4.3
+end-of-file macro, EOF, 4.3, 4.9.1
+end-of-file indicator, 4.9.1, 4.9.7.1
+end-of-line indicator, 2.2.1
+enumerated types, 3.1.2.5
+enumeration constant, 3.1.2, 3.1.3.3
+enumeration content, 3.5.2.3
+enumeration members, 3.5.2.2
+enumeration specifiers, 3.5.2.2
+enumeration tag, 3.5.2.3
+enumerator, 3.5.2.2
+environment, 2
+environment functions, 4.10.4
+environment list, 4.10.4.4
+environmental considerations, 2.2
+environmental limits, 2.2.4
+equal-sign punctuator, =, 3.1.6, 3.5, 3.5.7
+equal-to operator, ==, 3.3.9
+equality expressions, 3.3.9
+error, domain, 4.5.1
+error, range, 4.5.1
+error conditions, 4.5.1
+error handling functions, 4.9.10, 4.11.6.2
+error indicator, 4.9.1, 4.9.7.1, 4.9.7.3
+escape sequences, 2.2.1, 2.2.2, 3.1.3.4
+evaluation, 3.1.5, 3.3
+exception, 3.3
+exclusive OR assignment operator, ^=, 3.3.16.2
+exclusive OR operator, ^, 3.3.11
+executable program, 2.1.1.1
+execution environment, character sets, 2.2.1
+execution environment limits, 2.2.4.2
+execution environments, 2.1.2
+execution sequence, 2.1.2.3, 3.6
+explicit conversion, 3.2
+exponent part, floating constant, 3.1.3.1
+exponential functions, 4.5.4
+expression, 3.3
+expression, full, 3.6
+expression, primary, 3.3.1
+expression, unary, 3.3.3
+expression statement, 3.6.3
+extended character set, 1.6, 2.2.1.2
+external definitions, 3.7
+external identifiers, underscore, 4.1.2
+external linkage, 3.1.2.2
+external name, 3.1.2
+external object definitions, 3.7.2
+</FONT></P><P>
+<FONT size="-1">file, closing, 4.9.3
+file, creating, 4.9.3
+file, opening, 4.9.3
+file access functions, 4.9.5
+file identifier scope, 3.1.2.1, 3.7
+file name, 4.9.3
+file operations, 4.9.4
+file position indicator, 4.9.3
+file positioning functions, 4.9.9
+files, 4.9.3
+floating arithmetic functions, 4.5.6
+floating constants, 3.1.3.1
+floating suffix, f or F, 3.1.3.1
+floating types, 3.1.2.5
+floating-point numbers, 3.1.2.5
+form-feed character, 2.2.1, 3.1
+form-feed escape sequence, \f, 2.2.2, 3.1.3.4
+formatted input/output functions, 4.9.6
+forward references, definition of, 1.6
+freestanding execution environment, 2.1.2, 2.1.2.1
+full expression, 3.6
+fully buffered stream, 4.9.3
+function, definition of, 1.6, 3.5.4.3
+function, recursive call, 3.3.2.2
+function argument, 3.3.2.2
+function body, 3.7, 3.7.1
+function call, 3.3.2.2
+function call, library, 4.1.6
+function declarator, 3.5.4.3
+function definition, 3.5.4.3, 3.7.1
+function designator, 3.2.2.1
+function identifier scope, 3.1.2.1
+function image, 2.2.3
+function library, 2.1.1.1, 4.1.6
+function parameter, 2.1.2.2, 3.3.2.2
+function prototype, 3.1.2.1, 3.3.2.2, 3.5.4.3, 3.7.1
+function prototype identifier scope, 3.1.2.1
+function return, 3.6.6.4
+function type, 3.1.2.5
+function type conversion, 3.2.2.1
+function-call operator, ( ), 3.3.2.2
+future directions, 1.8, 3.9, 4.13
+future language directions, 3.9
+future library directions, 4.13
+</FONT></P><P>
+<FONT size="-1">general utility library, 4.10
+graphic characters, 2.2.1
+greater-than operator, >, 3.3.8
+greater-than-or-equal-to operator, >=, 3.3.8
+</FONT></P><P>
+<FONT size="-1">header names, 3.1, 3.1.7, 3.8.2
+headers, 4.1.2
+hexadecimal constant, 3.1.3.2
+hexadecimal digit, 3.1.3.2, 3.1.3.4
+hexadecimal escape sequence, 3.1.3.4
+high-order bit, 1.6
+horizontal-tab character, 2.2.1, 3.1
+horizontal-tab escape sequence, \t, 2.2.2, 3.1.3.4
+hosted execution environment, 2.1.2, 2.1.2.2
+hyperbolic functions, 4.5.3
+</FONT></P><P>
+<FONT size="-1">identifier, 3.1.2, 3.3.1
+identifier, maximum length, 3.1.2
+identifier, reserved, 4.1.2
+identifier linkage, 3.1.2.2
+identifier list, 3.5.4
+identifier name space, 3.1.2.3
+identifier scope, 3.1.2.1
+identifier type, 3.1.2.5
+IEEE floating-point arithmetic standard, 2.2.4.2
+implementation, definition of, 1.6
+implementation limits, 1.6, 2.2.4
+implementation-defined behavior, 1.6
+implicit conversion, 3.2
+implicit function declaration, 3.3.2.2
+inclusive OR assignment operator, |=, 3.3.16.2
+inclusive OR operator, |, 3.3.12
+incomplete type, 3.1.2.5
+increment operator, postfix, ++, 3.3.2.4
+increment operator, prefix, ++, 3.3.3.1
+indirection operator, *, 3.3.3.2
+inequality operator, !=, 3.3.9
+initialization, 2.1.2, 3.1.2.4, 3.2.2.1, 3.5.7, 3.6.2
+initializer, string literal, 3.2.2.1, 3.5.7
+initializer braces, 3.5.7
+initial shift state, 2.2.1.2, 4.10.7
+input/output, device, 2.1.2.3
+input/output header, 4.9
+integer arithmetic functions, 4.10.6
+integer character constant, 3.1.3.4
+integer constants, 3.1.3.2
+integer suffix, 3.1.3.2
+integer type, 3.1.2.5
+integer type conversion, 3.2.1.1, 3.2.1.2
+integral constant expression, 3.4
+integral promotions, 2.1.2.3, 3.2.1.1
+integral type, 3.1.2.5
+integral type conversion, 3.2.1.3
+interactive device, 2.1.2.3, 4.9.3, 4.9.5.3
+internal linkage, 3.1.2.2
+internal name, 3.1.2
+interrupt handler, 2.1.2.3, 2.2.3, 4.7
+ISO 4217 Currency and Funds Representation, 1.3, 4.4.2.1
+ISO 646 Invariant Code Set, 1.3, 2.2.1.1
+iteration statements, 3.6.5
+</FONT></P><P>
+<FONT size="-1">jump statements, 3.6.6
+</FONT></P><P>
+<FONT size="-1">keywords, 3.1.1
+</FONT></P><P>
+<FONT size="-1">label name, 3.1.2.1, 3.1.2.3
+labeled statements, 3.6.1
+language, 3 language, future directions, 3.9
+leading underscore in identifiers, 4.1.2
+left-shift assignment operator, <<=, 3.3.16.2
+left-shift operator, <<, 3.3.7
+length function, 4.11.6.3
+less-than operator, <, 3.3.8
+less-than-or-equal-to operator, <=, 3.3.8
+letter, 4.1.1
+lexical elements, 2.1.1.2, 3.1
+library, 2.1.1.1, 4
+library, future directions, 4.13
+library functions, use of, 4.1.6
+library terms, 4.1.1
+limits, environmental, 2.2.4
+limits, numerical, 2.2.4.2
+limits, translation, 2.2.4.1
+line buffered stream, 4.9.3
+line number, 3.8.4
+lines, 2.1.1.2, 3.8, 4.9.2
+linkages of identifiers, 3.1.2.2
+locale, definition of, 1.6
+localization, 4.4
+logarithmic functions, 4.5.4
+logical AND operator, &&, 3.3.13
+logical negation operator, !, 3.3.3.3
+logical OR operator, ||, 3.3.14
+logical source lines, 2.1.1.2
+long double suffix, l or L, 3.1.3.1
+long integer suffix, l or L, 3.1.3.2
+low-order bit, 1.6 lvalue, 3.2.2.1, 3.3.1, 3.3.2.4, 3.3.3.1, 3.3.16
+</FONT></P><P>
+<FONT size="-1">macro function vs. definition, 4.1.6
+macro name definition, 2.2.4.1
+macro names, predefined, 3.8.8
+macro, redefinition of, 3.8.3
+macro replacement, 3.8.3
+member-access operators, . and ->, 3.3.2.3
+memory management functions, 4.10.3
+minus operator, unary, -, 3.3.3.3
+modifiable lvalue, 3.2.2.1
+modulus function, 4.5.4.6
+multibyte characters, 2.2.1.2, 3.1.3.4, 4.10.7, 4.10.8
+multibyte functions, 4.10.7, 4.10.8
+multiplication assignment operator, *=, 3.3.16.2
+multiplication operator, *, 3.3.5
+multiplicative expressions, 3.3.5
+</FONT></P><P>
+<FONT size="-1">name, file, 4.9.3
+name spaces of identifiers, 3.1.2.3
+nearest-integer functions, 4.5.6
+new-line character, 2.1.1.2, 2.2.1, 3.1, 3.8, 3.8.4
+new-line escape sequence, \n, 2.2.2, 3.1.3.4
+nongraphic characters, 2.2.2, 3.1.3.4
+nonlocal jumps header, 4.6
+not-equal-to operator, !=, 3.3.9
+null character padding of binary streams, 4.9.2
+null character, \0, 2.2.1, 3.1.3.4, 3.1.4
+null pointer, 3.2.2.3
+null pointer constant, 3.2.2.3
+null preprocessing directive, 3.8.7
+null statement, 3.6.3
+number, floating-point, 3.1.2.5
+numerical limits, 2.2.4.2
+</FONT></P><P>
+<FONT size="-1">object, definition of, 1.6
+object type, 3.1.2.5
+obsolescence, 1.8, 3.9, 4.13
+octal constant, 3.1.3.2
+octal digit, 3.1.3.2, 3.1.3.4
+octal escape sequence, 3.1.3.4
+operand, 3.1.5, 3.3
+operating system, 2.1.2.1, 4.10.4.5
+operator, unary, 3.3.3
+operators, 3.1.5, 3.3
+OR assignment operator, exclusive, ^=, 3.3.16.2
+OR assignment operator, inclusive, |=, 3.3.16.2
+OR operator, exclusive, ^, 3.3.11
+OR operator, inclusive, |, 3.3.12
+OR operator, logical, ||, 3.3.14
+order of memory allocation, 4.10.3
+order of evaluation of expression, 3.3
+ordinary identifier name space, 3.1.2.3
+</FONT></P><P>
+<FONT size="-1">padding, null character, 4.9.2
+parameter, ellipsis, , ..., 3.5.4.3
+parameter, function, 3.3.2.2
+parameter, main function, 2.1.2.2
+parameter, 1.6
+parameter type list, 3.5.4.3
+parameters, program, 2.1.2.2
+parentheses punctuator, ( ), 3.1.6, 3.5.4.3
+parenthesized expression, 3.3.1
+physical source lines, 2.1.1.2
+plus operator, unary, +, 3.3.3.3
+pointer, null, 3.2.2.3
+pointer declarator, 3.5.4.1
+pointer operator, ->, 3.3.2.3
+pointer to function returning type, 3.3.2.2
+pointer type, 3.1.2.5
+pointer type conversion, 3.2.2.1, 3.2.2.3
+portability of implementations, 1.7
+position indicator, file, 4.9.3
+postfix decrement operator, --, 3.3.2.4
+postfix expressions, 3.3.2
+postfix increment operator, ++, 3.3.2.4
+power functions, 4.5.5
+precedence of expression operators, 3.3
+precedence of syntax rules, 2.1.1.2
+predefined macro names, 3.8.8
+prefix decrement operator, --, 3.3.3.1
+prefix increment operator, ++, 3.3.3.1
+preprocessing concatenation, 2.1.1.2, 3.8.3
+preprocessing directives, 2.1.1.2, 3.8
+preprocessing numbers, 3.1, 3.1.8
+preprocessing tokens, 2.1.1.2, 3.1, 3.8
+primary expressions, 3.3.1
+printing characters, 2.2.2, 4.3.1, 4.3.1.7
+program, conforming, 1.7
+program, strictly conforming, 1.7
+program diagnostics, 4.2.1
+program execution, 2.1.2.3
+program file, 2.1.1.1
+program image, 2.1.1.2
+program name, argv[0], 2.1.2.2
+program parameters, 2.1.2.2
+program startup, 2.1.2, 2.1.2.1, 2.1.2.2
+program structure, 2.1.1.1
+program termination, 2.1.2, 2.1.2.1, 2.1.2.2, 2.1.2.3
+promotions, default argument, 3.3.2.2
+promotions, integral, 2.1.2.3, 3.2.1.1
+prototype, function, 3.1.2.1, 3.3.2.2, 3.5.4.3, 3.7.1
+pseudo-random sequence functions, 4.10.2
+punctuators, 3.1.6
+</FONT></P><P>
+<FONT size="-1">qualified types, 3.1.2.5
+</FONT></P><P>
+<FONT size="-1">range error, 4.5.1
+recursive function call, 3.3.2.2
+redefinition of macro, 3.8.3
+reentrancy, 2.1.2.3, 2.2.3
+referenced type, 3.1.2.5
+relational expressions, 3.3.8
+reliability of data, interrupted, 2.1.2.3
+remainder assignment operator, %=, 3.3.16.2
+remainder operator, %, 3.3.5
+restore calling environment function, 4.6.2.1
+reserved identifiers, 4.1.2
+right-shift assignment operator, >>=, 3.3.16.2
+right-shift operator, >>, 3.3.7
+rvalue, 3.2.2.1
+</FONT></P><P>
+<FONT size="-1">save calling environment function, 4.6.1.1
+scalar type, 3.1.2.5
+scope of identifiers, 3.1.2.1
+search functions, 4.10.5.1, 4.11.5
+selection statements, 3.6.4
+semicolon punctuator, ;, 3.1.6, 3.5, 3.6.3
+sequence points, 2.1.2.3, 3.3, 3.6
+shift expressions, 3.3.7
+shift states, 2.2.1.2, 4.10.7
+side effects, 2.1.2.3, 3.3
+signal handler, 2.2.3, 4.7.1.1
+signals, 2.1.2.3, 2.2.3, 4.7
+signed integer types, 3.1.2.5, 3.1.3.2, 3.2.1.2
+simple assignment operator, =, 3.3.16.1
+single-precision arithmetic, 2.1.2.3
+sort function, 4.10.5.2
+source character set, 2.2.1
+source file inclusion, 3.8.2
+source files, 2.1.1.1
+source text, 2.1.1.2
+space character, 2.1.1.2, 2.2.1, 3.1
+standard streams, 4.9.1, 4.9.3
+standard header, float.h, 1.7, 2.2.4.2, 4.1.4
+standard header, limits.h, 1.7, 2.2.4.2, 4.1.4
+standard header, stdarg.h, 1.7, 4.8
+standard header, stddef.h, 1.7, 4.1.5
+standard headers, 4.1.2
+state-dependent encoding, 2.2.1.2, 4.10.7
+statements, 3.6
+static storage duration, 3.1.2.4
+storage duration, 3.1.2.4
+storage-class specifier, 3.5.1
+stream, fully buffered, 4.9.3
+stream, line buffered, 4.9.3
+stream, standard error, stderr, 4.9.1, 4.9.3
+stream, standard input, stdin, 4.9.1, 4.9.3
+stream, standard output, stdout, 4.9.1, 4.9.3
+stream, unbuffered, 4.9.3
+streams, 4.9.2
+strictly conforming program, 1.7
+string, 4.1.1
+string conversion functions, 4.10.1
+string handling header, 4.11
+string length, 4.1.1, 4.11.6.3
+string literal, 2.1.1.2, 2.2.1, 3.1.4, 3.3.1, 3.5.7
+structure/union arrow operator, ->, 3.3.2.3
+structure/union content, 3.5.2.3
+structure/union dot operator, ., 3.3.2.3
+structure/union member name space, 3.1.2.3
+structure/union specifiers, 3.5.2.1
+structure/union tag, 3.5.2.3
+structure/union type, 3.1.2.5, 3.5.2.1
+subtraction assignment operator, -=, 3.3.16.2
+subtraction operator, -, 3.3.6
+suffix, floating constant, 3.1.3.1
+suffix, integer constant, 3.1.3.2
+switch body, 3.6.4.2
+switch case label, 3.6.1, 3.6.4.2
+switch default label, 3.6.1, 3.6.4.2
+syntactic categories, 3
+syntax notation, 3
+syntax rules, precedence of, 2.1.1.2
+</FONT></P><P>
+<FONT size="-1">tab characters, 2.2.1
+tabs, white space, 3.1
+tag, enumeration, 3.5.2.3
+tag, structure/union, 3.5.2.3
+tag name space, 3.1.2.3
+tentative definitions, 3.7.2
+text stream, 4.9.2
+time components, 4.12.1
+time conversion functions, 4.12.3
+time manipulation functions, 4.12.2
+tokens, 2.1.1.2, 3.1, 3.8
+top type, 3.1.2.5
+translation environment, 2.1.1
+translation limits, 2.2.4.2
+translation phases, 2.1.1.2
+translation unit, 2.1.1.1, 3.7
+trigonometric functions, 4.5.2
+trigraph sequences, 2.1.1.2, 2.2.1.1
+type, character, 3.1.2.5, 3.2.2.1, 3.5.7
+type, compatible, 3.1.2.6, 3.5.2, 3.5.3, 3.5.4
+type, composite, 3.1.2.6
+type, const-qualified, 3.1.2.5, 3.5.3
+type, function, 3.1.2.5
+type, incomplete, 3.1.2.5
+type, object, 3.1.2.5
+type, qualified, 3.1.2.5
+type, unqualified, 3.1.2.5
+type, volatile-qualified, 3.1.2.5, 3.5.3
+type conversions, 3.2
+type definitions, 3.5.6
+type names, 3.5.5
+type specifiers, 3.5.2
+type qualifiers, 3.5.3
+types, 3.1.2.5
+</FONT></P><P>
+<FONT size="-1">unary arithmetic operators, 3.3.3.3
+unary expressions, 3.3.3
+unary minus operator, -, 3.3.3.3
+unary operators, 3.3.3
+unary plus operator, +, 3.3.3.3
+unbuffered stream, 4.9.3
+undefined behavior, 1.6
+underscore, leading, in identifiers, 4.1.2
+union tag, 3.5.2.3
+union type specifier, 3.1.2.5, 3.5.2, 3.5.2.1
+unqualified type, 3.1.2.5
+unsigned integer suffix, u or U, 3.1.3.2
+unsigned integer types, 3.1.2.5, 3.1.3.2
+unspecified behavior, 1.6
+usual arithmetic conversions, 3.2.1.5
+</FONT></P><P>
+<FONT size="-1">value part, floating constant, 3.1.3.1
+variable arguments header, 4.8
+vertical-tab character, 2.2.1, 3.1
+vertical-tab escape sequence, \v, 2.2.2, 3.1.3.4
+visibility of identifiers, 3.1.2.1
+void expression, 3.2.2.2
+volatile storage, 2.1.2.3
+volatile-qualified type, 3.1.2.5, 3.5.3
+</FONT></P><P>
+<FONT size="-1">white space, 2.1.1.2, 3.1, 3.8, 4.3.1.9
+wide character, 3.1.3.4
+wide character constant, 3.1.3.4
+wide string literal, 2.1.1.2, 3.1.4
+</FONT></P><FONT size="-1"><A name="1">1</A></FONT>
+<P>
+<FONT size="-1"> This Standard is designed to promote the portability of C programs
+among a variety of data-processing systems. It is intended for use by
+implementors and knowledgeable programmers, and is not a tutorial. It
+is accompanied by a Rationale document that explains many of the
+decisions of the Technical Committee that produced it.
+</FONT></P><FONT size="-1"><A name="2">2</A></FONT>
+<P>
+<FONT size="-1"> Strictly conforming programs are intended to be maximally portable
+among conforming implementations. Conforming programs may depend upon
+nonportable features of a conforming implementation.
+</FONT></P><FONT size="-1"><A name="3">3</A></FONT>
+<P>
+<FONT size="-1"> Implementations must behave as if these separate phases occur, even
+though many are typically folded together in practice.
+</FONT></P><FONT size="-1"><A name="4">4</A></FONT>
+<P>
+<FONT size="-1"> As described in <A href="
+ #3.1">3.1</A>, the process of dividing a source file's
+characters into preprocessing tokens is context-dependent. For
+example, see the handling of < within a #include preprocessing
+directive.
+</FONT></P><FONT size="-1"><A name="5">5</A></FONT>
+<P>
+<FONT size="-1"> The trigraph sequences enable the input of characters that are not
+defined in the "ISO 646-1983" Invariant Code Set, which is a subset of
+the seven-bit ASCII code set.
+</FONT></P><FONT size="-1"><A name="6">6</A></FONT>
+<P>
+<FONT size="-1"> Implementations should avoid imposing fixed translation limits
+whenever possible.
+</FONT></P><FONT size="-1"><A name="7">7</A></FONT>
+<P>
+<FONT size="-1"> See <A href="
+ #3.1.2.5">3.1.2.5</A></FONT></P><FONT size="-1"><A name="8">8</A></FONT>
+<P>
+<FONT size="-1"> This model precludes floating-point representations other than
+sign-magnitude.
+</FONT></P><FONT size="-1"><A name="9">9</A></FONT>
+<P>
+<FONT size="-1"> The floating-point model in that standard sums powers of from zero,
+so the values of the exponent limits are one less than shown here.
+</FONT></P><FONT size="-1"><A name="10">10</A></FONT>
+<P>
+<FONT size="-1"> See ``future language directions'' (<A href="
+ #3.9.1">3.9.1</A>).
+</FONT></P><FONT size="-1"><A name="11">11</A></FONT>
+<P>
+<FONT size="-1"> There is only one name space for tags even though three are
+possible.
+</FONT></P><FONT size="-1"><A name="12">12</A></FONT>
+<P>
+<FONT size="-1"> In the case of a volatile object, the last store may not be
+explicit in the program.
+</FONT></P><FONT size="-1"><A name="13">13</A></FONT>
+<P>
+<FONT size="-1"> A positional representation for integers that uses the binary
+digits 0 and 1, in which the values represented by successive bits are
+additive, begin with 1, and are multiplied by successive integral
+powers of 2, except perhaps the bit with the highest position.
+</FONT></P><FONT size="-1"><A name="14">14</A></FONT>
+<P>
+<FONT size="-1"> Note that aggregate type does not include union type because an
+object with union type can only contain one member at a time.
+</FONT></P><FONT size="-1"><A name="15">15</A></FONT>
+<P>
+<FONT size="-1"> There are three distinct combinations of qualified types.
+</FONT></P><FONT size="-1"><A name="16">16</A></FONT>
+<P>
+<FONT size="-1"> Two types need not be identical to be compatible.
+</FONT></P><FONT size="-1"><A name="17">17</A></FONT>
+<P>
+<FONT size="-1"> The semantics of these characters were discussed in <A href="
+ #2.2.2">2.2.2</A></FONT></P><FONT size="-1"><A name="18">18</A></FONT>
+<P>
+<FONT size="-1"> See ``future language directions'' (<A href="
+ #3.9.2">3.9.2</A>).
+</FONT></P><FONT size="-1"><A name="19">19</A></FONT>
+<P>
+<FONT size="-1"> A character string literal need not be a string (see <A href="
+ #4.1.1">4.1.1</A>),
+because a null character may be embedded in it by a \0 escape
+sequence.
+</FONT></P><FONT size="-1"><A name="20">20</A></FONT>
+<P>
+<FONT size="-1"> Thus, sequences of characters that resemble escape sequences cause
+undefined behavior.
+</FONT></P><FONT size="-1"><A name="21">21</A></FONT>
+<P>
+<FONT size="-1"> Thus comments do not nest.
+</FONT></P><FONT size="-1"><A name="22">22</A></FONT>
+<P>
+<FONT size="-1"> In a two's-complement representation, there is no actual change in
+the bit pattern except filling the high-order bits with copies of the
+sign bit if the unsigned integer has greater size.
+</FONT></P><FONT size="-1"><A name="23">23</A></FONT>
+<P>
+<FONT size="-1"> The remaindering operation done when a value of integral type is
+converted to unsigned type need not be done when a value of floating
+type is converted to unsigned type. Thus the range of portable values
+is [0, U type _MAX +1).
+</FONT></P><FONT size="-1"><A name="24">24</A></FONT>
+<P>
+<FONT size="-1"> The name ``lvalue'' comes originally from the assignment
+expression E1 = E2 , in which the left operand E1 must be a
+(modifiable) lvalue. It is perhaps better considered as representing
+an object ``locator value.'' What is sometimes called ``rvalue'' is in
+this Standard described as the ``value of an expression.'' An obvious
+example of an lvalue is an identifier of an object. As a further
+example, if E is a unary expression that is a pointer to an object, *E
+is an lvalue that designates the object to which E points.
+</FONT></P><FONT size="-1"><A name="25">25</A></FONT>
+<P>
+<FONT size="-1"> Because this conversion does not occur, the operand of the sizeof
+operator remains a function designator and violates the constraint in
+<A href="
+ #3.3.3.4">3.3.3.4</A></FONT></P><FONT size="-1"><A name="26">26</A></FONT>
+<P>
+<FONT size="-1"> This paragraph renders undefined statement expressions such as
+i = ++i + 1; while allowing i = i + 1;
+</FONT></P><FONT size="-1"><A name="27">27</A></FONT>
+<P>
+<FONT size="-1"> The syntax specifies the precedence of operators in the evaluation
+of an expression, which is the same as the order of the major
+subsections of this section, highest precedence first. Thus, for
+example, the expressions allowed as the operands of the binary +
+operator (<A href="
+ #3.3.6">3.3.6</A>) shall be those expressions defined in <A href="
+ #3.3.1">3.3.1</A> through
+<A href="
+ #3.3.6">3.3.6</A> The exceptions are cast expressions (<A href="
+ #3.3.4">3.3.4</A>) as operands of
+unary operators (<A href="
+ #3.3.3">3.3.3</A>), and an operand contained between any of the
+following pairs of operators: grouping parentheses () (<A href="
+ #3.3.1">3.3.1</A>),
+subscripting brackets [] (<A href="
+ #3.3.2.1">3.3.2.1</A>), function-call parentheses ()
+(<A href="
+ #3.3.2.2">3.3.2.2</A>), and the conditional operator ?: (<A href="
+ #3.3.15">3.3.15</A>). Within each
+major subsection, the operators have the same precedence. Left- or
+right-associativity is indicated in each subsection by the syntax for
+the expressions discussed therein.
+</FONT></P><FONT size="-1"><A name="28">28</A></FONT>
+<P>
+<FONT size="-1"> The intent of this list is to specify those circumstances in which
+an object may or may not be aliased.
+</FONT></P><FONT size="-1"><A name="29">29</A></FONT>
+<P>
+<FONT size="-1"> Most often, this is the result of converting an identifier that is
+a function designator.
+</FONT></P><FONT size="-1"><A name="30">30</A></FONT>
+<P>
+<FONT size="-1"> That is, a function with external linkage and no information about
+its parameters that returns an int . If in fact it is not defined as
+having type ``function returning int ,'' the behavior is undefined.
+</FONT></P><FONT size="-1"><A name="31">31</A></FONT>
+<P>
+<FONT size="-1"> A function may change the values of its parameters, but these
+changes cannot affect the values of the arguments. On the other hand,
+it is possible to pass a pointer to an object, and the function may
+change the value of the object pointed to. A parameter declared to
+have array or function type is converted to a parameter with a pointer
+type as described in
+</FONT></P><FONT size="-1"><A name="32">32</A></FONT>
+<P>
+<FONT size="-1"> If &E is a valid pointer expression (where & is the ``address-of''
+operator, which generates a pointer to its operand) the expression
+(&E)->MOS is the same as E.MOS .
+</FONT></P><FONT size="-1"><A name="33">33</A></FONT>
+<P>
+<FONT size="-1"> The ``byte orders'' for scalar types are invisible to isolated
+programs that do not indulge in type punning (for example, by
+assigning to one member of a union and inspecting the storage by
+accessing another member that is an appropriately sized array of
+character type), but must be accounted for when conforming to
+externally-imposed storage layouts.
+</FONT></P><FONT size="-1"><A name="34">34</A></FONT>
+<P>
+<FONT size="-1"> It is always true that if E is a function designator or an lvalue
+that is a valid operand of the unary & operator, *&E is a function
+designator or an lvalue equal to E . If *P is an lvalue and T is the
+name of an object pointer type, the cast expression *(T)P is an lvalue
+that has a type compatible with that to which T points. Among the
+invalid values for dereferencing a pointer by the unary * operator are
+a null pointer, an address inappropriately aligned for the type of
+object pointed to, or the address of an object that has automatic
+storage duration when execution of the block in which the object is
+declared and of all enclosed blocks has terminated.
+</FONT></P><FONT size="-1"><A name="35">35</A></FONT>
+<P>
+<FONT size="-1"> When applied to a parameter declared to have array or function
+type, the sizeof operator yields the size of the pointer obtained by
+converting as in <A href="
+ #3.2.2.1">3.2.2.1</A>; see <A href="
+ #3.7.1">3.7.1</A></FONT></P><FONT size="-1"><A name="36">36</A></FONT>
+<P>
+<FONT size="-1"> A cast does not yield an lvalue.
+</FONT></P><FONT size="-1"><A name="37">37</A></FONT>
+<P>
+<FONT size="-1"> The mapping functions for converting a pointer to an integer or an
+integer to a pointer are intended to be consistent with the addressing
+structure of the execution environment.
+</FONT></P><FONT size="-1"><A name="38">38</A></FONT>
+<P>
+<FONT size="-1"> The expression a<b<c is not interpreted as in ordinary
+mathematics. As the syntax indicates, it means (a<b)<c ; in other
+words, ``if a is less than b compare 1 to c ; otherwise compare 0 to c
+.''
+</FONT></P><FONT size="-1"><A name="39">39</A></FONT>
+<P>
+<FONT size="-1"> Because of the precedences, a<b == c<d is 1 whenever a<b and c<d
+have the same truth-value.
+</FONT></P><FONT size="-1"><A name="40">40</A></FONT>
+<P>
+<FONT size="-1"> If invalid prior pointer operations, such as accesses outside
+array bounds, produced undefined behavior, the effect of subsequent
+comparisons is undefined.
+</FONT></P><FONT size="-1"><A name="41">41</A></FONT>
+<P>
+<FONT size="-1"> A conditional expression does not yield an lvalue.
+</FONT></P><FONT size="-1"><A name="42">42</A></FONT>
+<P>
+<FONT size="-1"> The asymmetric appearance of these constraints with respect to
+type qualifiers is due to the conversion (specified in <A href="
+ #3.2.2.1">3.2.2.1</A>) that
+changes lvalues to ``the value of the expression'' which removes any
+type qualifiers from the top type of the expression.
+</FONT></P><FONT size="-1"><A name="43">43</A></FONT>
+<P>
+<FONT size="-1"> A comma operator does not yield an lvalue.
+</FONT></P><FONT size="-1"><A name="44">44</A></FONT>
+<P>
+<FONT size="-1"> The operand of a sizeof operator is not evaluated (<A href="
+ #3.3.3.4">3.3.3.4</A>), and
+thus any operator in <A href="
+ #3.3">3.3</A> may be used.
+</FONT></P><FONT size="-1"><A name="45">45</A></FONT>
+<P>
+<FONT size="-1"> An integral constant expression must be used to specify the size
+of a bit-field member of a structure, the value of an enumeration
+constant, the size of an array, or the value of a case constant.
+Further constraints that apply to the integral constant expressions
+used in conditional-inclusion preprocessing directives are discussed
+in <A href="
+ #3.8.1">3.8.1</A></FONT></P><FONT size="-1"><A name="46">46</A></FONT>
+<P>
+<FONT size="-1"> Thus in the following initialization, static int i = 2 || 1 / 0;
+the expression is a valid integral constant expression with value one.
+</FONT></P><FONT size="-1"><A name="47">47</A></FONT>
+<P>
+<FONT size="-1"> Function definitions have a different syntax, described in <A href="
+ #3.7.1">3.7.1</A></FONT></P><FONT size="-1"><A name="48">48</A></FONT>
+<P>
+<FONT size="-1"> See ``future language directions'' (<A href="
+ #3.9.3">3.9.3</A>).
+</FONT></P><FONT size="-1"><A name="49">49</A></FONT>
+<P>
+<FONT size="-1"> The implementation may treat any register declaration simply as an
+auto declaration. However, whether or not addressable storage is
+actually used, the address of any part of an object declared with
+storage-class specifier register may not be computed, either
+explicitly (by use of the unary & operator as discussed in <A href="
+ #3.3.3.2">3.3.3.2</A>)
+or implicitly (by converting an array name to a pointer as discussed
+in <A href="
+ #3.2.2.1">3.2.2.1</A>). Thus the only operator that can be applied to an array
+declared with storage-class specifier register is sizeof .
+</FONT></P><FONT size="-1"><A name="50">50</A></FONT>
+<P>
+<FONT size="-1"> The unary & (address-of) operator may not be applied to a
+bit-field object; thus there are no pointers to or arrays of bit-field
+objects.
+</FONT></P><FONT size="-1"><A name="51">51</A></FONT>
+<P>
+<FONT size="-1"> An unnamed bit-field is useful for padding to conform to
+externally-imposed layouts.
+</FONT></P><FONT size="-1"><A name="52">52</A></FONT>
+<P>
+<FONT size="-1"> Thus, the identifiers of enumeration constants in the same scope
+shall all be distinct from each other and from other identifiers
+declared in ordinary declarators.
+</FONT></P><FONT size="-1"><A name="53">53</A></FONT>
+<P>
+<FONT size="-1"> A similar construction with enum does not exist and is not
+necessary as there can be no mutual dependencies between the
+declaration of an enumerated type and any other type.
+</FONT></P><FONT size="-1"><A name="54">54</A></FONT>
+<P>
+<FONT size="-1"> It is not needed, for example, when a typedef name is declared to
+be a specifier for a structure or union, or when a pointer to or a
+function returning a structure or union is being declared. (See
+incomplete types in <A href="
+ #3.1.2.5">3.1.2.5</A>) The specification shall be complete
+before such a function is called or defined.
+</FONT></P><FONT size="-1"><A name="55">55</A></FONT>
+<P>
+<FONT size="-1"> Of course, when the declaration is of a typedef name, subsequent
+declarations can make use of the typedef name to declare objects
+having the specified structure, union, or enumerated type.
+</FONT></P><FONT size="-1"><A name="56">56</A></FONT>
+<P>
+<FONT size="-1"> The implementation may place a const object that is not volatile
+in a read-only region of storage. Moreover, the implementation need
+not allocate storage for such an object if its address is never used.
+</FONT></P><FONT size="-1"><A name="57">57</A></FONT>
+<P>
+<FONT size="-1"> This applies to those objects that behave as if they were defined
+with qualified types, even if they are never actually defined as
+objects in the program (such as an object at a memory-mapped
+input/output address).
+</FONT></P><FONT size="-1"><A name="58">58</A></FONT>
+<P>
+<FONT size="-1"> A volatile declaration may be used to describe an object
+corresponding to a memory-mapped input/output port or an object
+accessed by an asynchronously interrupting function. Actions on
+objects so declared shall not be ``optimized out'' by an
+implementation or reordered except as permitted by the rules for
+evaluating expressions.
+</FONT></P><FONT size="-1"><A name="59">59</A></FONT>
+<P>
+<FONT size="-1"> Both of these can only occur through the use of typedef s.
+</FONT></P><FONT size="-1"><A name="60">60</A></FONT>
+<P>
+<FONT size="-1"> When several ``array of'' specifications are adjacent, a
+multi-dimensional array is declared.
+</FONT></P><FONT size="-1"><A name="61">61</A></FONT>
+<P>
+<FONT size="-1"> The macros defined in the <stdarg.h> header (<A href="
+ #4.8">4.8</A>) may be used to
+access arguments that follow an ellipsis.
+</FONT></P><FONT size="-1"><A name="62">62</A></FONT>
+<P>
+<FONT size="-1"> See ``future language directions'' (<A href="
+ #3.9.4">3.9.4</A>).
+</FONT></P><FONT size="-1"><A name="63">63</A></FONT>
+<P>
+<FONT size="-1"> If both function types are ``old style,'' parameter types are not
+compared.
+</FONT></P><FONT size="-1"><A name="64">64</A></FONT>
+<P>
+<FONT size="-1"> As indicated by the syntax, empty parentheses in a type name are
+interpreted as ``function with no parameter specification,'' rather
+than redundant parentheses around the omitted identifier.
+</FONT></P><FONT size="-1"><A name="65">65</A></FONT>
+<P>
+<FONT size="-1"> Unlike in the base document, any automatic duration object may be
+initialized.
+</FONT></P><FONT size="-1"><A name="66">66</A></FONT>
+<P>
+<FONT size="-1"> Such as assignments, and function calls which have side effects.
+</FONT></P><FONT size="-1"><A name="67">67</A></FONT>
+<P>
+<FONT size="-1"> Thus specifies initialization for the loop; the controlling
+expression, specifies an evaluation made before each iteration, such
+that execution of the loop continues until the expression compares
+equal to 0; specifies an operation (such as incrementing) that is
+performed after each iteration.
+</FONT></P><FONT size="-1"><A name="68">68</A></FONT>
+<P>
+<FONT size="-1"> Following the contin: label is a null statement.
+</FONT></P><FONT size="-1"><A name="69">69</A></FONT>
+<P>
+<FONT size="-1"> Thus, if an identifier declared with external linkage is not used
+in an expression, there need be no external definition for it.
+</FONT></P><FONT size="-1"><A name="70">70</A></FONT>
+<P>
+<FONT size="-1"> The intent is that the top type in a function definition cannot be
+inherited from a typedef: typedef int F(void); /* type F is ``function
+of no arguments returning int '' */ F f, g; /* f and g both have type
+compatible with F */ F f { /*...*/ } /* WRONG: syntax/constraint error
+*/ F g() { /*...*/ } /* WRONG: declares that g returns a function */
+int f(void) { /*...*/ } /* RIGHT: f has type compatible with F */ int
+g() { /*...*/ } /* RIGHT: g has type compatible with F */ F *e(void) {
+/*...*/ } /* e returns a pointer to a function */ F *((e))(void) {
+/*...*/ } /* same: parentheses irrelevant */ int (*fp)(void); /* fp
+points to a function that has type F */ F *Fp; /* Fp points to a
+function that has type F */
+</FONT></P><FONT size="-1"><A name="71">71</A></FONT>
+<P>
+<FONT size="-1"> See ``future language directions'' (<A href="
+ #3.9.5">3.9.5</A>).
+</FONT></P><FONT size="-1"><A name="72">72</A></FONT>
+<P>
+<FONT size="-1"> A parameter is in effect declared at the head of the compound
+statement that constitutes the function body, and therefore may not be
+redeclared in the function body (except in an enclosed block).
+</FONT></P><FONT size="-1"><A name="73">73</A></FONT>
+<P>
+<FONT size="-1"> Thus preprocessing directives are commonly called ``lines.'' These
+``lines'' have no other syntactic significance, as all white space is
+equivalent except in certain situations during preprocessing (see the
+# character string literal creation operator in <A href="
+ #3.8.3.2">3.8.3.2</A>, for
+example).
+</FONT></P><FONT size="-1"><A name="74">74</A></FONT>
+<P>
+<FONT size="-1"> Because the controlling constant expression is evaluated during
+translation phase 4, all identifiers either are or are not macro names
+--- there simply are no keywords, enumeration constants, and so on.
+</FONT></P><FONT size="-1"><A name="75">75</A></FONT>
+<P>
+<FONT size="-1"> Thus the constant expression in the following #if directive and if
+statement is not guaranteed to evaluate to the same value in these two
+contexts. #if 'z' - 'a' == 25 if ('z' - 'a' == 25)
+</FONT></P><FONT size="-1"><A name="76">76</A></FONT>
+<P>
+<FONT size="-1"> As indicated by the syntax, a preprocessing token shall not follow
+a #else or #endif directive before the terminating new-line character.
+However, comments may appear anywhere in a source file, including
+within a preprocessing directive.
+</FONT></P><FONT size="-1"><A name="77">77</A></FONT>
+<P>
+<FONT size="-1"> Note that adjacent string literals are not concatenated into a
+single string literal (see the translation phases in <A href="
+ #2.1.1.2">2.1.1.2</A>); thus
+an expansion that results in two string literals is an invalid
+directive.
+</FONT></P><FONT size="-1"><A name="78">78</A></FONT>
+<P>
+<FONT size="-1"> Since, by macro-replacement time, all character constants and
+string literals are preprocessing tokens, not sequences possibly
+containing identifier-like subsequences (see <A href="
+ #2.1.1.2">2.1.1.2</A>, translation
+phases), they are never scanned for macro names or parameters.
+</FONT></P><FONT size="-1"><A name="79">79</A></FONT>
+<P>
+<FONT size="-1"> Thus indicating a Standard-conforming implementation.
+</FONT></P><FONT size="-1"><A name="80">80</A></FONT>
+<P>
+<FONT size="-1"> The functions that make use of the decimal-point character are
+localeconv , fprintf , fscanf , printf , scanf , sprintf , sscanf ,
+vfprintf , vprintf , vsprintf , atof , and strtod .
+</FONT></P><FONT size="-1"><A name="81">81</A></FONT>
+<P>
+<FONT size="-1"> A header is not necessarily a source file, nor are the < and >
+delimited sequences in header names necessarily valid source file
+names.
+</FONT></P><FONT size="-1"><A name="82">82</A></FONT>
+<P>
+<FONT size="-1"> The list of reserved external identifiers includes errno , setjmp ,
+and va_end .
+</FONT></P><FONT size="-1"><A name="83">83</A></FONT>
+<P>
+<FONT size="-1"> The macro errno need not be the identifier of an object. It might
+be a modifiable lvalue resulting from a function call (for example,
+*errno() ).
+</FONT></P><FONT size="-1"><A name="84">84</A></FONT>
+<P>
+<FONT size="-1"> Thus, a program that uses errno for error checking should set it
+to zero before a library function call, then inspect it before a
+subsequent library function call.
+</FONT></P><FONT size="-1"><A name="85">85</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.1">4.13.1</A>).
+</FONT></P><FONT size="-1"><A name="86">86</A></FONT>
+<P>
+<FONT size="-1"> This means that an implementation must provide an actual function
+for each library function, even if it also provides a macro for that
+function.
+</FONT></P><FONT size="-1"><A name="87">87</A></FONT>
+<P>
+<FONT size="-1"> Because external identifiers and some macro names beginning with
+an underscore are reserved, implementations may provide special
+semantics for such names. For example, the identifier _BUILTIN_abs
+could be used to indicate generation of in-line code for the abs
+function. Thus, the appropriate header could specify #define abs(x)
+_BUILTIN_abs(x) for a compiler whose code generator will accept it.
+In this manner, a user desiring to guarantee that a given library
+function such as abs will be a genuine function may write #undef abs
+whether the implementation's header provides a macro implementation of
+abs or a builtin implementation. The prototype for the function,
+which precedes and is hidden by any macro definition, is thereby
+revealed also.
+</FONT></P><FONT size="-1"><A name="88">88</A></FONT>
+<P>
+<FONT size="-1"> The message written might be of the form Assertion failed: file
+line
+</FONT></P><FONT size="-1"><A name="89">89</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.2">4.13.2</A>).
+</FONT></P><FONT size="-1"><A name="90">90</A></FONT>
+<P>
+<FONT size="-1"> In an implementation that uses the seven-bit ASCII character set,
+the printing characters are those whose values lie from 0x20 (space)
+through 0x7E (tilde); the control characters are those whose values
+lie from 0 (NUL) through 0x1F (US), and the character 0x7F (DEL).
+</FONT></P><FONT size="-1"><A name="91">91</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.3">4.13.3</A>).
+</FONT></P><FONT size="-1"><A name="92">92</A></FONT>
+<P>
+<FONT size="-1"> The only functions in <A href="
+ #4.3">4.3</A> whose behavior is not affected by the
+current locale are isdigit and isxdigit .
+</FONT></P><FONT size="-1"><A name="93">93</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.4">4.13.4</A>).
+</FONT></P><FONT size="-1"><A name="94">94</A></FONT>
+<P>
+<FONT size="-1"> In an implementation that supports infinities, this allows
+infinity as an argument to be a domain error if the mathematical
+domain of the function does not include infinity.
+</FONT></P><FONT size="-1"><A name="95">95</A></FONT>
+<P>
+<FONT size="-1"> These functions are useful for dealing with unusual conditions
+encountered in a low-level function of a program.
+</FONT></P><FONT size="-1"><A name="96">96</A></FONT>
+<P>
+<FONT size="-1"> For example, by executing a return statement or because another
+longjmp call has caused a transfer to a setjmp invocation in a
+function earlier in the set of nested calls.
+</FONT></P><FONT size="-1"><A name="97">97</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.5">4.13.5</A>). The names of the
+signal numbers reflect the following terms (respectively): abort,
+floating-point exception, illegal instruction, interrupt, segmentation
+violation, and termination.
+</FONT></P><FONT size="-1"><A name="98">98</A></FONT>
+<P>
+<FONT size="-1"> Of course, the contents of the file name strings are subject to
+other system-specific constraints.
+</FONT></P><FONT size="-1"><A name="99">99</A></FONT>
+<P>
+<FONT size="-1"> An implementation need not distinguish between text streams and
+binary streams. In such an implementation, there need be no new-line
+characters in a text stream nor any limit to the length of a line.
+</FONT></P><FONT size="-1"><A name="100">100</A></FONT>
+<P>
+<FONT size="-1"> This is described in the Base Document as a That term is not used
+in this Standard to avoid confusion with a pointer to an object that
+has type FILE .
+</FONT></P><FONT size="-1"><A name="101">101</A></FONT>
+<P>
+<FONT size="-1"> Among the reasons the implementation may cause the rename
+function to fail are that the file is open or that it is necessary to
+copy its contents to effectuate its renaming.
+</FONT></P><FONT size="-1"><A name="102">102</A></FONT>
+<P>
+<FONT size="-1"> Files created using strings generated by the tmpnam function are
+temporary only in the sense that their names should not collide with
+those generated by conventional naming rules for the implementation.
+It is still necessary to use the remove function to remove such files
+when their use is ended, and before program termination.
+</FONT></P><FONT size="-1"><A name="103">103</A></FONT>
+<P>
+<FONT size="-1"> Additional characters may follow these sequences.
+</FONT></P><FONT size="-1"><A name="104">104</A></FONT>
+<P>
+<FONT size="-1"> The primary use of the freopen function is to change the file
+associated with a standard text stream ( stderr , stdin , or stdout ),
+as those identifiers need not be modifiable lvalues to which the value
+returned by the fopen function may be assigned.
+</FONT></P><FONT size="-1"><A name="105">105</A></FONT>
+<P>
+<FONT size="-1"> The buffer must have a lifetime at least as great as the open
+stream, so the stream should be closed before a buffer that has
+automatic storage duration is deallocated upon block exit.
+</FONT></P><FONT size="-1"><A name="106">106</A></FONT>
+<P>
+<FONT size="-1"> Note that 0 is taken as a flag, not as the beginning of a field
+width.
+</FONT></P><FONT size="-1"><A name="107">107</A></FONT>
+<P>
+<FONT size="-1"> No special provisions are made for multibyte characters.
+</FONT></P><FONT size="-1"><A name="108">108</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.6">4.13.6</A>).
+</FONT></P><FONT size="-1"><A name="109">109</A></FONT>
+<P>
+<FONT size="-1"> No special provisions are made for multibyte characters.
+</FONT></P><FONT size="-1"><A name="110">110</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.6">4.13.6</A>).
+</FONT></P><FONT size="-1"><A name="111">111</A></FONT>
+<P>
+<FONT size="-1"> As vfprintf , vsprintf , and vprintf invoke the va_arg macro, the
+value of arg after the return is indeterminate.
+</FONT></P><FONT size="-1"><A name="112">112</A></FONT>
+<P>
+<FONT size="-1"> An end-of-file and a read error can be distinguished by use of
+the feof and ferror functions.
+</FONT></P><FONT size="-1"><A name="113">113</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.7">4.13.7</A>).
+</FONT></P><FONT size="-1"><A name="114">114</A></FONT>
+<P>
+<FONT size="-1"> Note that this need not be the same as the representation of
+floating-point zero or a null pointer constant.
+</FONT></P><FONT size="-1"><A name="115">115</A></FONT>
+<P>
+<FONT size="-1"> Each function is called as many times as it was registered.
+</FONT></P><FONT size="-1"><A name="116">116</A></FONT>
+<P>
+<FONT size="-1"> Notice that the key-to-member comparison an ordering on the
+array.
+</FONT></P><FONT size="-1"><A name="117">117</A></FONT>
+<P>
+<FONT size="-1"> In a two's complement representation, the absolute value of the
+most negative number cannot be represented.
+</FONT></P><FONT size="-1"><A name="118">118</A></FONT>
+<P>
+<FONT size="-1"> The array will not be null- or zero-terminated if the value
+returned is n .
+</FONT></P><FONT size="-1"><A name="119">119</A></FONT>
+<P>
+<FONT size="-1"> See ``future library directions'' (<A href="
+ #4.13.8">4.13.8</A>).
+</FONT></P><FONT size="-1"><A name="120">120</A></FONT>
+<P>
+<FONT size="-1"> Thus, if there is no null character in the first n characters of
+the array pointed to by s2 , the result will not be null-terminated.
+</FONT></P><FONT size="-1"><A name="121">121</A></FONT>
+<P>
+<FONT size="-1"> Thus the maximum number of characters that end up in the array
+pointed to by s1 is strlen(s1)+n+1 .
+</FONT></P><FONT size="-1"><A name="122">122</A></FONT>
+<P>
+<FONT size="-1"> The contents of ``holes'' used as padding for purposes of
+alignment within structure objects are indeterminate, unless the
+contents of the entire object have been set explicitly, as by the
+calloc or memset function. Strings shorter than their allocated space
+and unions may also cause problems in comparison.
+</FONT></P><FONT size="-1"><A name="123">123</A></FONT>
+<P>
+<FONT size="-1"> The range [0, 60] for tm_sec allows for the occasional leap
+second.
+</FONT></P><FONT size="-1"><A name="124">124</A></FONT>
+<P>
+<FONT size="-1"> Thus, a positive or zero value for tm_isdst causes the mktime
+function initially to presume that Daylight Saving Time, respectively,
+is or is not in effect for the specified time. A negative value for
+tm_isdst causes the mktime function to attempt to determine whether
+Daylight Saving Time is in effect for the specified time.
+</FONT></P><PRE>
+<P class="code-block"><FONT size="+0"> (C) Formatting: 2004-2005, Unicals Group (http://dev.unicals.com). Revision 1.0.1000.
+</FONT></P></PRE></BODY></HTML>
@@ -8,7 +8,7 @@ functor Driver(P: PPC): DRIVER = struct val initConfig: config = { file = NONE, includeDirs = [] } - fun die msg = (printLn msg; Posix.Process.exit $ Word8.fromInt 1) + fun die msg = (printf `msg `"\n"; Posix.Process.exit $ Word8.fromInt 1) fun parseCmdArgs { file, includeDirs } [] = if file = NONE then diff --git a/exn_handler.fun b/exn_handler.fun index 2d970cc..b95e847 100644 --- a/exn_handler.fun +++ b/exn_handler.fun @@ -2,7 +2,7 @@ functor ExnHandler(structure T: TOKENIZER; structure P: PPC): EXN_HANDLER = struct - fun eprint s = printLn $ "error: " ^ s + fun eprint s = printf `"error: " `s % fun otherExn e = let @@ -10,10 +10,10 @@ struct in eprint $ "exception " ^ exnMessage e ^ " was raised"; if hist = [] then - (printLn "No stack trace is avaliable"; - printLn "Recompile with -const \"Exn.keepHistory true\"") + (output "No stack trace is avaliable\n"; + output "Recompile with -const \"Exn.keepHistory true\"\n") else - List.app (fn x => printLn $ "\t" ^ x) hist + List.app (fn x => printf `"\t" `x `"\n" %) hist end fun exit code = Posix.Process.exit $ Word8.fromInt code @@ -26,9 +26,9 @@ struct OS.SysErr (str, _) => str | _ => exnMessage cause in - printLn $ prefix ^ reason + printf `prefix `reason `"\n" % end - | ioExn _ = (printLn "ioExn: unreachable"; exit 254) + | ioExn _ = (output "ioExn: unreachable\n"; exit 254) fun handler e = (case e of diff --git a/hashtable.sig b/hashtable.sig index b714fd6..b96bfb3 100644 --- a/hashtable.sig +++ b/hashtable.sig @@ -1,10 +1,11 @@ signature HASHTABLE = sig type 'a t - exception HashtableFull - exception Exists + exception Full and Exists - val create: int -> 'a t + val createLog: int -> 'a t val insert: 'a t -> string -> 'a -> unit val lookup: 'a t -> string -> 'a option + val lookup2: 'a t -> string -> + ('a -> 'a option * 'b) -> (unit -> 'b) -> 'b end diff --git a/hashtable.sml b/hashtable.sml index 5b89ebd..6ec7277 100644 --- a/hashtable.sml +++ b/hashtable.sml @@ -1,60 +1,75 @@ -structure Hashtable :> HASHTABLE = struct - (* (Array, (cells occupied, total size)) *) - type 'a t = ((string * 'a) option) array * (int * int) +structure Hashtable: HASHTABLE = struct + open Array + open Word - exception HashtableFull - exception Exists + (* buf * taken * mask *) + type 'a t = (string * 'a) option array * int * word - fun create size = (Array.array (size, NONE), (0, size)) + val ` = Word.fromInt + val ! = Word.toInt - val fillLimit = 0.75 + infixr 4 << + infix 5 andb + infixr 6 + + infixr 7 * - val ` = Word32.fromInt + fun createLog log = + let + val size = `1 << `log + val mask = size - `1 + in + (array (Word.toInt size, NONE), 0, mask) + end + + exception Full and Exists - fun hashFunc key = - List.foldl (fn (x, acc) => acc * `31 + `(ord x)) (`0) $ explode key + fun hash key = + List.foldl (fn (c, s) => s * `31 + `(ord c)) (`17) (explode key) - fun insert (buf, (taken, total)) key value = - if Real.fromInt (taken + 1) / Real.fromInt total > fillLimit then - raise HashtableFull + fun checkFreeSpace (array, taken, _) = + let + open Real + val ` = fromInt + in + if `taken / `(length array) > 0.75 then + raise Full else - let - open Array - val hash = hashFunc key - - (* TODO: use bitwise manipulation instead of mod *) - val i = ref $ Word32.toInt $ Word32.mod (hash, `(length buf)) - val flag = ref true - in - while !flag do ( - case sub (buf, !i) of - NONE => (update (buf, !i, SOME (key, value)); flag := false) - | SOME (key', _) => - if key' = key then - raise Exists - else - i := (!i + 1) mod (length buf) - ) - end - - fun lookup (buf, _) key = + () + end + + fun next idx mask = (idx + `1) andb mask + + fun lookup2 ((array, _, mask): 'a t) (key: string) f g = let - open Array - val hash = hashFunc key + fun find idx = + case sub (array, !idx) of + NONE => g () + | SOME (key', v: 'a) => + if key' = key then + case f v of + (NONE, res) => res + | (SOME v, res) => + (update (array, !idx, SOME (key, v)); res) + else + find (next idx mask) + in + find (hash key andb mask) + end + + fun lookup H key = lookup2 H key (fn v => (NONE, SOME v)) (fn () => NONE) - val i = ref $ Word32.toInt $ Word32.mod (hash, `(length buf)) - val flag = ref true - val result = ref NONE + fun insert (H as (array, _, mask)) key v = + let + val () = checkFreeSpace H; + fun find idx = + case sub (array, !idx) of + NONE => update (array, !idx, SOME (key, v)) + | SOME (key', _) => + if key' = key then + raise Exists + else + find (next idx mask) in - while !flag do ( - case sub (buf, !i) of - SOME (key', value) => - if key' = key then - (result := SOME value; flag := false) - else - i := (!i + 1) mod (length buf) - | NONE => flag := false - ); - !result + find (hash key andb mask) end end @@ -5,11 +5,17 @@ struct datatype tkPos = TkPos of T.S.pos + type macroBody = (T.token * T.S.pos) list + datatype macro = + ObjMacro of macroBody | + FuncMacro of string list * macroBody + type t = { streams: T.S.t list, buffer: (T.token * T.S.pos) list, - macros: (T.token * T.S.pos) list H.t, (* body is stored reversed *) + + macros: (bool * macro) H.t, EOSreached: bool, incDirs: string list @@ -33,7 +39,7 @@ struct fun raiseTkErrorSPos pos msg = raiseTkError msg (TkPos pos) fun tkErrorPrint (TkPos pos, msg) = - printLn $ T.S.pos2str pos ^ ": " ^ msg + printf A1 T.S.pos2str pos `": " `msg `"\n" % fun raiseTkErrorExp pos exp = raise TkErrorExp (pos, exp) fun raiseTkErrorExpSPos pos exp = raiseTkErrorExp (TkPos pos) exp @@ -42,28 +48,28 @@ struct let val printEtk = fn ExpTk tk => T.printToken tk - | ExpId => print "identifier" - | ExpConst => print "constant" - | ExpUnop => print "unary operator" - | ExpBinop => print "binary operator" - | ExpOp => print "operator" + | ExpId => output "identifier" + | ExpConst => output "constant" + | ExpUnop => output "unary operator" + | ExpBinop => output "binary operator" + | ExpOp => output "operator" fun printExpList [] = raise Unreachable | printExpList [etk] = printEtk etk | printExpList [etk1, etk2] = ( printEtk etk1; - print " or "; + output " or "; printEtk etk2 ) | printExpList (etk :: etks) = ( printEtk etk; - print ", "; + output ", "; printExpList etks ) in - print $ T.S.pos2str pos ^ ": expected "; + printf A1 T.S.pos2str pos `": expected " %; printExpList exp; - print "\n" + output "\n" end val updatePpc = fn z => @@ -78,7 +84,7 @@ struct z fun create { fname, incDirs } = - { streams = [T.S.create fname], buffer = [], macros = H.create 10, + { streams = [T.S.create fname], buffer = [], macros = H.createLog 10, EOSreached = false, incDirs } datatype IncludeArg = @@ -130,34 +136,34 @@ struct fun findFile arg (stream, incDirs) = case arg of - LocalInc (arg, pos) => ( + LocalInc (arg, pos) => ( + let + val dir = OS.Path.getParent o T.S.getFname $ stream + val path = OS.Path.concat (dir, arg) + + val (path, instream) = (path, TextIO.openIn path) + in + (path, instream) + end handle + OS.Path.Path => raiseTkErrorSPos pos "invalid argument" + | Size => raiseTkErrorSPos pos "resulting path is too long" + | IO.Io v => raise IO.Io v + ) + | ExternalInc (arg, pos) => + let + fun try (dir :: tail) = ( let - val dir = OS.Path.getParent o T.S.getFname $ stream val path = OS.Path.concat (dir, arg) - - val (path, instream) = (path, TextIO.openIn path) in - (path, instream) - end handle - OS.Path.Path => raiseTkErrorSPos pos "invalid argument" - | Size => raiseTkErrorSPos pos "resulting path is too long" - | IO.Io v => raise IO.Io v + SOME (path, TextIO.openIn path) + end handle _ => try tail ) - | ExternalInc (arg, pos) => - let - fun try (dir :: tail) = ( - let - val path = OS.Path.concat (dir, arg) - in - SOME (path, TextIO.openIn path) - end handle _ => try tail - ) - | try [] = NONE - in - case try incDirs of - SOME pair => pair - | NONE => raiseTkErrorSPos pos "unable to find header" - end + | try [] = NONE + in + case try incDirs of + SOME pair => pair + | NONE => raiseTkErrorSPos pos "unable to find header" + end fun handleInclude (P as { streams = head :: tail, incDirs, ... }: t) = let @@ -169,59 +175,141 @@ struct end | handleInclude _ = raise Unreachable - fun handleDefine (P as { streams = head :: _, ... }: t) = + fun getDefineMacroBody stream acc = + let + val (tk, pos, stream) = T.getToken stream + in + case tk of + T.NewLine => (acc, stream) + | T.EOS => raiseTkErrorExpSPos pos [ExpTk T.NewLine] + | _ => getDefineMacroBody stream ((tk, pos) :: acc) + end + + fun isFuncMacroDefine nameLength (T.S.Pos (_, line1, col1)) stream = + let + val (tk, T.S.Pos (_, line2, col2), _) = T.getToken stream + in + tk = T.LParen andalso line1 = line2 andalso col1 + nameLength = col2 + end + + fun parseDefineObjMacro stream = + let + val (body, stream) = getDefineMacroBody stream [] + in + (ObjMacro body, stream) + end + + fun getSpecific stream expList = + let + val (tk, pos, stream) = T.getToken stream + in + raise Unimplemented + end + + fun parseDefineMacroArgs stream = + let + datatype arg = + Arg of string * T.S.pos | + LastArg of string * T.S.pos | + EmptyArg + in + raise Unimplemented + end + + fun parseDefineFuncMacro stream = + let + val (_, _, stream) = T.getToken stream + in + raise Unimplemented + end + + fun parseDefine stream = let fun getName stream = let val (tk, pos, stream) = T.getToken stream in case tk of - T.Id id => (id, pos, stream) - | _ => raiseTkErrorExpSPos pos [ExpId] + T.Id id => (id, pos, stream) + | _ => raiseTkErrorExpSPos pos [ExpId] end - fun getBody stream acc = - let - val (tk, pos, stream) = T.getToken stream - in - case tk of - T.NewLine => (acc, stream) - | T.EOS => raiseTkErrorExpSPos pos [ExpTk T.NewLine] - | _ => getBody stream ((tk, pos) :: acc) - end + val (macroName, pos, stream) = getName stream - val (macroName, pos, head) = getName head - val (macroBody, head) = getBody head [] + val parser = + if isFuncMacroDefine (size macroName) pos stream then + parseDefineFuncMacro + else + parseDefineObjMacro + + val (macro, stream) = parser stream + in + ((macroName, pos), macro, stream) + end - val () = H.insert (#macros P) macroName macroBody handle + fun handleDefine (P as { streams = head :: _, ... }: t) = + let + val ((macroName, pos), macro, head) = parseDefine head + + val () = H.insert (#macros P) macroName (false, macro) handle H.Exists => raiseTkErrorSPos pos "macro redefinition" in updatePpc P u#streams (fn s => head :: tl s) % end | handleDefine _ = raise Unreachable - fun handleRegularToken tk pos P = + val directiveTable = [ + (T.CppInclude, handleInclude), + (T.CppDefine, handleDefine) + ] + + fun expandObjMacro (id, pos) body ppc = let - fun def () = (tk, TkPos pos, P) + val mstart = (T.MacroStart id, pos) + val mend = (T.MacroEnd id, + if body = [] then pos else (#2 o hd) body) + val revBody = List.concat [[mend], body, [mstart]] + in + updatePpc ppc u#buffer (fn buf => List.revAppend (revBody, buf)) % + end + + fun expandFuncMacro (_, _) (_, _) _ = + raise Unimplemented + + fun handleRegularToken tk pos ppc = + let + fun def () = (tk, TkPos pos, ppc) + + fun checkAndMark (true, _) = (NONE, NONE) + | checkAndMark (false, macro) = (SOME (true, macro), SOME macro) in case tk of - T.Id id => ( - case H.lookup (#macros P) id of - NONE => def () - | SOME body => - let - val mstart = (T.MacroStart id, pos) - val mend = (T.MacroEnd, - if body = [] then pos else (#2 o hd) body) - val revBody = List.concat [[mend], body, [mstart]] - in - getToken $ updatePpc P - u#buffer (fn buf => List.revAppend (revBody, buf)) % - end - ) - | _ => def () + T.Id id => ( + case H.lookup2 (#macros ppc) id + checkAndMark (fn () => NONE) + of + NONE => def () + | SOME (ObjMacro body) => + getToken $ expandObjMacro (id, pos) body ppc + | SOME (FuncMacro (arg, body)) => + getToken $ expandFuncMacro (id, pos) (arg, body) ppc + ) + | T.MacroEnd id => + let + val () = H.lookup2 (#macros ppc) id + (fn (_, body) => (SOME (false, body), ())) + (fn () => raise Unreachable) + in + def () + end + | _ => def () end + and handleToken tk pos ppc = + case List.find (fn (tk', _) => tk' = tk) directiveTable of + SOME (_, f) => getToken o f $ ppc + | NONE => handleRegularToken tk pos ppc + and getToken (P as { streams = [stream], EOSreached = true, ... }) = let val (pos, stream) = T.S.EOFpos stream @@ -229,72 +317,64 @@ struct (T.EOS, TkPos pos, updatePpc P s#streams [stream] %) end | getToken (P as { buffer = (tk, pos) :: tail, ... }: t) = - handleRegularToken tk pos (updatePpc P s#buffer tail %) + handleToken tk pos (updatePpc P s#buffer tail %) | getToken (P as { streams = head :: tail, ... }: t) = let val (tk, pos, head) = T.getToken head - val directiveTable = [ - (T.CppInclude, handleInclude), - (T.CppDefine, handleDefine) - ] in if tk = T.EOS then case tail of - [] => getToken $ updatePpc P s#EOSreached true % - | _ => getToken $ updatePpc P s#streams tail % + [] => getToken $ updatePpc P s#EOSreached true % + | _ => getToken $ updatePpc P s#streams tail % else - case List.find (fn (tk', _) => tk' = tk) directiveTable of - SOME (_, f) => getToken o f $ - updatePpc P s#streams (head :: tail) % - | NONE => - let - val ppc = updatePpc P u#streams (fn s => head :: tl s) % - in - handleRegularToken tk pos ppc - end + handleToken tk pos $ updatePpc P s#streams (head :: tail) % end | getToken _ = raise Unreachable - - fun debugPrint' ppc shouldPrintLine (fname, line) = + fun debugPrint' ppc (shouldPrintLine, indent) (fname, line) = let val (tk, pos, ppc) = getToken ppc val TkPos (t as (T.S.Pos (fname', line', col))) = pos - fun printLine () = - printOnNL $ fname' ^ ":" ^ Int.toString line' ^ "\n\t" + fun repeat n s = String.concat (List.tabulate (n, fn _ => s)) + val Indent = fn z => bind A0 (fn () => repeat indent "\t") z - fun finish shouldPrintLine = + fun printLine () = printf `"\n" Indent `fname' `":" I line' `" \t" % + + fun finish pair = if tk <> T.EOS then - debugPrint' ppc shouldPrintLine (fname', line') + debugPrint' ppc pair (fname', line') else () in case tk of - T.MacroStart macroName => ( - printOnNL $ "macro " ^ macroName ^ " (" ^ T.S.pos2str t ^ ") {"; - finish true - ) - | T.MacroEnd => (printOnNL "}\n"; finish true) - | _ => ( - if shouldPrintLine orelse fname' <> fname - orelse line' <> line - then - printLine() - else - (); - print $ Int.toString col ^ ":"; - T.printToken tk; - print " "; - finish false - ) + T.MacroStart macroName => ( + printf `"\n" Indent A1 T.S.pos2str t `": macro " `macroName `" {" %; + finish (true, indent + 1) + ) + | T.MacroEnd id => ( + output "\n"; + printf Indent `"} " `id %; + finish (true, indent - 1) + ) + | _ => ( + if shouldPrintLine orelse fname' <> fname orelse line' <> line + then + printLine() + else + (); + printf I col `":" %; + T.printToken tk; + printf `" " %; + finish (false, indent) + ) end fun debugPrint fname incDirs = let val ppc = create { fname, incDirs } in - debugPrint' ppc true ("", 0); - print "\n" + debugPrint' ppc (true, 0) ("", 0); + output "\n" end end @@ -69,10 +69,6 @@ structure Stream :> STREAM = struct fun getPosRaw off (S as { cache = (prevOff, line, col), fname, contents, ... }: t) = let - (* - val () = printLn $ "raw: " ^ Int.toString off ^ ", " ^ Int.toString prevOff - *) - fun calcPos curOff (line, col) = if curOff = off then (line, col) diff --git a/tokenizer.fun b/tokenizer.fun index 5162308..12b3257 100644 --- a/tokenizer.fun +++ b/tokenizer.fun @@ -17,7 +17,7 @@ struct EOS | NewLine | MacroStart of string | - MacroEnd | + MacroEnd of string | Num of numConst | @@ -152,7 +152,6 @@ struct [ (NewLine, "@NewLine"), (EOS, "@EOS"), - (MacroEnd, "@Mend"), (kwBreak, &"break"), (kwCase, &"case"), @@ -284,6 +283,7 @@ struct val token2str = fn Id s => s | MacroStart macro => "m(" ^ macro ^ ")" + | MacroEnd macro => "mend(" ^ macro ^ ")" | Num (IntConst (it, str, sfx)) => let val intType = @@ -304,7 +304,7 @@ struct SOME (_, repr) => repr | NONE => raise TokenWithoutRepr - fun printToken tk = print $ token2str tk + fun printToken tk = printf A1 token2str tk % fun isIdStart c = Char.isAlpha c orelse c = #"_" fun isIdBody c = Char.isAlphaNum c orelse c = #"_" @@ -395,8 +395,8 @@ struct List.app (fn (v, p) => fsmInsert' T 0 v $ explode p) tokenRepr; if !nextState <> maxStates then - printLn $ "note: Fsm table size can be smaller: " - ^ Int.toString (!nextState) ^ " is enough" + printf `"note: Fsm table size can be smaller: " + I (!nextState) `" is enough" % else (); T end @@ -406,7 +406,7 @@ struct let fun printRow i row = if i = length row then - print "\n" + output "\n" else let val state = sub (row, i) @@ -414,7 +414,7 @@ struct if state = ~1 then () else - print ((str (chr i)) ^ ": " ^ (Int.toString state) ^ ", "); + printf C (chr i) `": " I state `", " %; printRow (i + 1) row end @@ -425,14 +425,14 @@ struct let val (tk, row) = sub (buf, rowNum) in - print ((token2string tk) ^ ": "); + printf A1 token2string tk `": " %; printRow 0 row; print' (rowNum + 1) buf end in - print ("NextState: " ^ Int.toString (!nextState) ^ "\n"); + printf `"NextState: " I (!nextState) `"\n" %; print' 0 buf; - print "\n" + output "\n" end *) @@ -509,7 +509,7 @@ struct fun keywordHashtableGen () = let - val table = H.create 128 + val table = H.createLog 7 val () = List.app (fn (tk, repr) => @@ -983,19 +983,17 @@ struct fun print' line _ ((NewLine, _) :: tks) = print' (line + 1) true tks | print' line firstOnLine ((tk, _) :: tks) = ( - if firstOnLine then ( - print "\n"; - printLn $ fname ^ ":" ^ Int.toString line; - print "\t") + if firstOnLine then + printf `"\n" `fname `":" I line `"\t" % else (); printToken tk; - print " "; + output " "; print' line false tks ) | print' _ _ [] = () in print' 1 true tkl; - print "\n" + output "\n" end end diff --git a/tokenizer.sig b/tokenizer.sig index 7ea6f63..f79e62a 100644 --- a/tokenizer.sig +++ b/tokenizer.sig @@ -14,7 +14,7 @@ signature TOKENIZER = sig EOS | NewLine | MacroStart of string | - MacroEnd | + MacroEnd of string | Num of numConst | |