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77 lines
3.1 KiB
HTML
77 lines
3.1 KiB
HTML
4 years ago
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<html lang="en">
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<head>
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<title>Else - The C Preprocessor</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="The C Preprocessor">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Conditional-Syntax.html#Conditional-Syntax" title="Conditional Syntax">
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<link rel="prev" href="Defined.html#Defined" title="Defined">
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<link rel="next" href="Elif.html#Elif" title="Elif">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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Copyright (C) 1987-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation. A copy of
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the license is included in the
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section entitled ``GNU Free Documentation License''.
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This manual contains no Invariant Sections. The Front-Cover Texts are
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(a) (see below), and the Back-Cover Texts are (b) (see below).
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development.
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<style type="text/css"><!--
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pre.display { font-family:inherit }
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span.sansserif { font-family:sans-serif; font-weight:normal; }
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--></style>
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</head>
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<body>
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<div class="node">
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<a name="Else"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Elif.html#Elif">Elif</a>,
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Previous: <a rel="previous" accesskey="p" href="Defined.html#Defined">Defined</a>,
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Up: <a rel="up" accesskey="u" href="Conditional-Syntax.html#Conditional-Syntax">Conditional Syntax</a>
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<hr>
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</div>
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<h4 class="subsection">4.2.4 Else</h4>
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<p><a name="index-g_t_0023else-90"></a>The ‘<samp><span class="samp">#else</span></samp>’ directive can be added to a conditional to provide
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alternative text to be used if the condition fails. This is what it
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looks like:
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<pre class="smallexample"> #if <var>expression</var>
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<var>text-if-true</var>
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#else /* Not <var>expression</var> */
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<var>text-if-false</var>
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#endif /* Not <var>expression</var> */
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</pre>
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<p class="noindent">If <var>expression</var> is nonzero, the <var>text-if-true</var> is included and
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the <var>text-if-false</var> is skipped. If <var>expression</var> is zero, the
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opposite happens.
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<p>You can use ‘<samp><span class="samp">#else</span></samp>’ with ‘<samp><span class="samp">#ifdef</span></samp>’ and ‘<samp><span class="samp">#ifndef</span></samp>’, too.
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</body></html>
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