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| 22 | <title>Static Local Variables (GNU C Language Manual)</title>
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| 31 | <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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| 32 | <link href="Variables.html" rel="up" title="Variables">
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| 58 | <span id="Static-Local-Variables"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="Extern-Declarations.html" accesskey="n" rel="next">Extern Declarations</a>, Previous: <a href="File_002dScope-Variables.html" accesskey="p" rel="prev">File-Scope Variables</a>, Up: <a href="Variables.html" accesskey="u" rel="up">Variables</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="Static-Local-Variables-1"></span><h3 class="section">20.7 Static Local Variables</h3>
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| 64 | <span id="index-static-local-variables"></span>
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| 65 | <span id="index-variables_002c-static-local"></span>
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| 66 | <span id="index-static"></span>
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| 67 |
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| 68 | <p>The keyword <code>static</code> in a local variable declaration says to
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| 69 | allocate the storage for the variable permanently, just like a
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| 70 | file-scope variable, even if the declaration is within a function.
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| 71 | </p>
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| 72 | <p>Here’s an example:
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| 73 | </p>
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| 74 | <div class="example">
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| 75 | <pre class="example">int
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| 76 | increment_counter ()
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| 77 | {
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| 78 | static int counter = 0;
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| 79 | return ++counter;
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| 80 | }
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| 81 | </pre></div>
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| 82 |
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| 83 | <p>The scope of the name <code>counter</code> runs from the declaration to the
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| 84 | end of the containing block, just like an automatic local variable,
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| 85 | but its storage is permanent, so the value persists from one call to
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| 86 | the next. As a result, each call to <code>increment_counter</code>
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| 87 | returns a different, unique value.
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| 88 | </p>
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| 89 | <p>The initial value of a static local variable has the same limitations
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| 90 | as for file-scope variables: it can’t depend on the contents of
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| 91 | storage or call any functions. It can use the address of a file-scope
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| 92 | variable or a static local variable, because those addresses are
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| 93 | determined before the program runs.
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| 94 | </p>
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| 95 |
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| 96 |
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| 97 |
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| 98 | </body>
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| 99 | </html>
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