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| 22 | <title>elif (GNU C Language Manual)</title>
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| 57 | <body lang="en">
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| 58 | <span id="elif"></span><div class="header">
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| 59 | <p>
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| 60 | Previous: <a href="else.html" accesskey="p" rel="prev">else</a>, Up: <a href="Conditional-Syntax.html" accesskey="u" rel="up">Conditional Syntax</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Index.html" title="Index" rel="index">Index</a>]</p>
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| 61 | </div>
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| 62 | <hr>
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| 63 | <span id="The-_0023elif-directive"></span><h4 class="subsubsection">26.6.2.5 The <code>#elif</code> directive</h4>
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| 64 |
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| 65 | <span id="index-_0023elif"></span>
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| 66 | <p>One common case of nested conditionals is used to check for more than two
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| 67 | possible alternatives. For example, you might have
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| 68 | </p>
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| 69 | <div class="example">
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| 70 | <pre class="example">#if X == 1
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| 71 | /* <span class="roman">…</span> */
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| 72 | #else /* X != 1 */
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| 73 | #if X == 2
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| 74 | /* <span class="roman">…</span> */
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| 75 | #else /* X != 2 */
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| 76 | /* <span class="roman">…</span> */
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| 77 | #endif /* X != 2 */
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| 78 | #endif /* X != 1 */
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| 79 | </pre></div>
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| 80 |
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| 81 | <p>Another conditional directive, <code>#elif</code>, allows this to be
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| 82 | abbreviated as follows:
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| 83 | </p>
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| 84 | <div class="example">
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| 85 | <pre class="example">#if X == 1
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| 86 | /* <span class="roman">…</span> */
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| 87 | #elif X == 2
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| 88 | /* <span class="roman">…</span> */
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| 89 | #else /* X != 2 and X != 1*/
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| 90 | /* <span class="roman">…</span> */
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| 91 | #endif /* X != 2 and X != 1*/
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| 92 | </pre></div>
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| 93 |
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| 94 | <p><code>#elif</code> stands for “else if”. Like <code>#else</code>, it goes in the
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| 95 | middle of a conditional group and subdivides it; it does not require a
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| 96 | matching <code>#endif</code> of its own. Like <code>#if</code>, the <code>#elif</code>
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| 97 | directive includes an expression to be tested. The text following the
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| 98 | <code>#elif</code> is processed only if the original <code>#if</code>-condition
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| 99 | failed and the <code>#elif</code> condition succeeds.
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| 100 | </p>
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| 101 | <p>More than one <code>#elif</code> can go in the same conditional group. Then
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| 102 | the text after each <code>#elif</code> is processed only if the <code>#elif</code>
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| 103 | condition succeeds after the original <code>#if</code> and all previous
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| 104 | <code>#elif</code> directives within it have failed.
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| 105 | </p>
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| 106 | <p><code>#else</code> is allowed after any number of <code>#elif</code> directives, but
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| 107 | <code>#elif</code> may not follow <code>#else</code>.
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| 108 | </p>
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| 109 |
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| 110 |
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| 111 |
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