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70 lines
3.1 KiB
HTML
70 lines
3.1 KiB
HTML
4 years ago
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<title>Pointer Arith - Using the GNU Compiler Collection (GCC)</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Using the GNU Compiler Collection (GCC)">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="C-Extensions.html#C-Extensions" title="C Extensions">
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<link rel="prev" href="Subscripting.html#Subscripting" title="Subscripting">
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<link rel="next" href="Pointers-to-Arrays.html#Pointers-to-Arrays" title="Pointers to Arrays">
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Copyright (C) 1988-2015 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; with the
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Invariant Sections being ``Funding Free Software'', the Front-Cover
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(see below). A copy of the license is included in the section entitled
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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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</head>
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<body>
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<div class="node">
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<a name="Pointer-Arith"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Pointers-to-Arrays.html#Pointers-to-Arrays">Pointers to Arrays</a>,
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Previous: <a rel="previous" accesskey="p" href="Subscripting.html#Subscripting">Subscripting</a>,
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Up: <a rel="up" accesskey="u" href="C-Extensions.html#C-Extensions">C Extensions</a>
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<hr>
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</div>
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<h3 class="section">6.23 Arithmetic on <code>void</code>- and Function-Pointers</h3>
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<p><a name="index-void-pointers_002c-arithmetic-3007"></a><a name="index-void_002c-size-of-pointer-to-3008"></a><a name="index-function-pointers_002c-arithmetic-3009"></a><a name="index-function_002c-size-of-pointer-to-3010"></a>
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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>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><a name="index-Wpointer_002darith-3011"></a>The option <samp><span class="option">-Wpointer-arith</span></samp> requests a warning if these extensions
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are used.
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</body></html>
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