100 lines
4.3 KiB
HTML
100 lines
4.3 KiB
HTML
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<head>
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<title>Using the GNU Compiler Collection (GCC): Pointer Arith</title>
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<meta name="description" content="Using the GNU Compiler Collection (GCC): Pointer Arith">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="C-Extensions.html#C-Extensions" rel="up" title="C Extensions">
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<link href="Pointers-to-Arrays.html#Pointers-to-Arrays" rel="next" title="Pointers to Arrays">
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<a name="Pointer-Arith"></a>
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<div class="header">
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<p>
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Next: <a href="Pointers-to-Arrays.html#Pointers-to-Arrays" accesskey="n" rel="next">Pointers to Arrays</a>, Previous: <a href="Subscripting.html#Subscripting" accesskey="p" rel="prev">Subscripting</a>, Up: <a href="C-Extensions.html#C-Extensions" accesskey="u" rel="up">C Extensions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Arithmetic-on-void_002d-and-Function_002dPointers"></a>
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<h3 class="section">6.23 Arithmetic on <code>void</code>- and Function-Pointers</h3>
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<a name="index-void-pointers_002c-arithmetic"></a>
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<a name="index-void_002c-size-of-pointer-to"></a>
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<a name="index-function-pointers_002c-arithmetic"></a>
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<a name="index-function_002c-size-of-pointer-to"></a>
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<p>In GNU C, addition and subtraction operations are supported on pointers to
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<code>void</code> and on pointers to functions. This is done by treating the
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size of a <code>void</code> or of a function as 1.
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</p>
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<p>A consequence of this is that <code>sizeof</code> is also allowed on <code>void</code>
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and on function types, and returns 1.
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</p>
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<a name="index-Wpointer_002darith-1"></a>
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<p>The option <samp>-Wpointer-arith</samp> requests a warning if these extensions
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are used.
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</p>
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</html>
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