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| 22 | <title>for-Index Declarations (GNU C Language Manual)</title>
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| 32 | <link href="Loop-Statements.html" rel="up" title="Loop Statements">
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| 33 | <link href="continue-Statement.html" rel="next" title="continue Statement">
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| 58 | <span id="for_002dIndex-Declarations"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="continue-Statement.html" accesskey="n" rel="next">continue Statement</a>, Previous: <a href="Omitted-for_002dExpressions.html" accesskey="p" rel="prev">Omitted for-Expressions</a>, Up: <a href="Loop-Statements.html" accesskey="u" rel="up">Loop Statements</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="for_002dIndex-Declarations-1"></span><h4 class="subsection">19.6.7 <code>for</code>-Index Declarations</h4>
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| 64 |
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| 65 | <p>You can declare loop-index variables directly in the <var>start</var>
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| 66 | portion of the <code>for</code>-loop, like this:
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| 67 | </p>
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| 68 | <div class="example">
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| 69 | <pre class="example">for (int i = 0; i < n; ++i)
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| 70 | {
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| 71 | <span class="roman">…</span>
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| 72 | }
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| 73 | </pre></div>
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| 74 |
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| 75 | <p>This kind of <var>start</var> is limited to a single declaration; it can
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| 76 | declare one or more variables, separated by commas, all of which are
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| 77 | the same <var>basetype</var> (<code>int</code>, in this example):
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| 78 | </p>
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| 79 | <div class="example">
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| 80 | <pre class="example">for (int i = 0, j = 1, *p = NULL; i < n; ++i, ++j, ++p)
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| 81 | {
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| 82 | <span class="roman">…</span>
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| 83 | }
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| 84 | </pre></div>
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| 85 |
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| 86 | <p>The scope of these variables is the <code>for</code> statement as a whole.
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| 87 | See <a href="Variable-Declarations.html">Variable Declarations</a> for a explanation of <var>basetype</var>.
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| 88 | </p>
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| 89 | <p>Variables declared in <code>for</code> statements should have initializers.
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| 90 | Omitting the initialization gives the variables unpredictable initial
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| 91 | values, so this code is erroneous.
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| 92 | </p>
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| 93 | <div class="example">
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| 94 | <pre class="example">for (int i; i < n; ++i)
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| 95 | {
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| 96 | <span class="roman">…</span>
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| 97 | }
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| 98 | </pre></div>
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| 99 |
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| 100 |
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| 101 |
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| 102 |
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| 103 | </body>
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