103 lines
4.5 KiB
HTML
103 lines
4.5 KiB
HTML
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
|
|
<html>
|
||
|
|
<!-- Copyright (C) 1987-2016 Free Software Foundation, Inc.
|
||
|
|
|
||
|
|
Permission is granted to copy, distribute and/or modify this document
|
||
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
||
|
|
any later version published by the Free Software Foundation. A copy of
|
||
|
|
the license is included in the
|
||
|
|
section entitled "GNU Free Documentation License".
|
||
|
|
|
||
|
|
This manual contains no Invariant Sections. The Front-Cover Texts are
|
||
|
|
(a) (see below), and the Back-Cover Texts are (b) (see below).
|
||
|
|
|
||
|
|
(a) The FSF's Front-Cover Text is:
|
||
|
|
|
||
|
|
A GNU Manual
|
||
|
|
|
||
|
|
(b) The FSF's Back-Cover Text is:
|
||
|
|
|
||
|
|
You have freedom to copy and modify this GNU Manual, like GNU
|
||
|
|
software. Copies published by the Free Software Foundation raise
|
||
|
|
funds for GNU development. -->
|
||
|
|
<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
|
||
|
|
<head>
|
||
|
|
<title>The C Preprocessor: Conditional Syntax</title>
|
||
|
|
|
||
|
|
<meta name="description" content="The C Preprocessor: Conditional Syntax">
|
||
|
|
<meta name="keywords" content="The C Preprocessor: Conditional Syntax">
|
||
|
|
<meta name="resource-type" content="document">
|
||
|
|
<meta name="distribution" content="global">
|
||
|
|
<meta name="Generator" content="makeinfo">
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
||
|
|
<link href="index.html#Top" rel="start" title="Top">
|
||
|
|
<link href="Index-of-Directives.html#Index-of-Directives" rel="index" title="Index of Directives">
|
||
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
||
|
|
<link href="Conditionals.html#Conditionals" rel="up" title="Conditionals">
|
||
|
|
<link href="Ifdef.html#Ifdef" rel="next" title="Ifdef">
|
||
|
|
<link href="Conditional-Uses.html#Conditional-Uses" rel="prev" title="Conditional Uses">
|
||
|
|
<style type="text/css">
|
||
|
|
<!--
|
||
|
|
a.summary-letter {text-decoration: none}
|
||
|
|
blockquote.smallquotation {font-size: smaller}
|
||
|
|
div.display {margin-left: 3.2em}
|
||
|
|
div.example {margin-left: 3.2em}
|
||
|
|
div.indentedblock {margin-left: 3.2em}
|
||
|
|
div.lisp {margin-left: 3.2em}
|
||
|
|
div.smalldisplay {margin-left: 3.2em}
|
||
|
|
div.smallexample {margin-left: 3.2em}
|
||
|
|
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
|
||
|
|
div.smalllisp {margin-left: 3.2em}
|
||
|
|
kbd {font-style:oblique}
|
||
|
|
pre.display {font-family: inherit}
|
||
|
|
pre.format {font-family: inherit}
|
||
|
|
pre.menu-comment {font-family: serif}
|
||
|
|
pre.menu-preformatted {font-family: serif}
|
||
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
||
|
|
pre.smallexample {font-size: smaller}
|
||
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
||
|
|
pre.smalllisp {font-size: smaller}
|
||
|
|
span.nocodebreak {white-space:nowrap}
|
||
|
|
span.nolinebreak {white-space:nowrap}
|
||
|
|
span.roman {font-family:serif; font-weight:normal}
|
||
|
|
span.sansserif {font-family:sans-serif; font-weight:normal}
|
||
|
|
ul.no-bullet {list-style: none}
|
||
|
|
-->
|
||
|
|
</style>
|
||
|
|
|
||
|
|
|
||
|
|
</head>
|
||
|
|
|
||
|
|
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
|
||
|
|
<a name="Conditional-Syntax"></a>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Deleted-Code.html#Deleted-Code" accesskey="n" rel="next">Deleted Code</a>, Previous: <a href="Conditional-Uses.html#Conditional-Uses" accesskey="p" rel="prev">Conditional Uses</a>, Up: <a href="Conditionals.html#Conditionals" accesskey="u" rel="up">Conditionals</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html#Index-of-Directives" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
<a name="Conditional-Syntax-1"></a>
|
||
|
|
<h3 class="section">4.2 Conditional Syntax</h3>
|
||
|
|
|
||
|
|
<a name="index-_0023if"></a>
|
||
|
|
<p>A conditional in the C preprocessor begins with a <em>conditional
|
||
|
|
directive</em>: ‘<samp>#if</samp>’, ‘<samp>#ifdef</samp>’ or ‘<samp>#ifndef</samp>’.
|
||
|
|
</p>
|
||
|
|
<table class="menu" border="0" cellspacing="0">
|
||
|
|
<tr><td align="left" valign="top">• <a href="Ifdef.html#Ifdef" accesskey="1">Ifdef</a>:</td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="If.html#If" accesskey="2">If</a>:</td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="Defined.html#Defined" accesskey="3">Defined</a>:</td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="Else.html#Else" accesskey="4">Else</a>:</td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="Elif.html#Elif" accesskey="5">Elif</a>:</td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|