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85 lines
3.6 KiB
HTML
85 lines
3.6 KiB
HTML
4 years ago
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<html lang="en">
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<title>Traditional miscellany - The C Preprocessor</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="The C Preprocessor">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Traditional-Mode.html#Traditional-Mode" title="Traditional Mode">
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<link rel="prev" href="Traditional-macros.html#Traditional-macros" title="Traditional macros">
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<link rel="next" href="Traditional-warnings.html#Traditional-warnings" title="Traditional warnings">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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Copyright (C) 1987-2015 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. A copy of
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the license is included in the
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section entitled ``GNU Free Documentation License''.
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This manual contains no Invariant Sections. The Front-Cover Texts are
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(a) (see below), and the Back-Cover Texts are (b) (see below).
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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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--></style>
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</head>
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<body>
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<div class="node">
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<a name="Traditional-miscellany"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Traditional-warnings.html#Traditional-warnings">Traditional warnings</a>,
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Previous: <a rel="previous" accesskey="p" href="Traditional-macros.html#Traditional-macros">Traditional macros</a>,
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Up: <a rel="up" accesskey="u" href="Traditional-Mode.html#Traditional-Mode">Traditional Mode</a>
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<hr>
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</div>
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<h3 class="section">10.3 Traditional miscellany</h3>
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<p>Here are some things to be aware of when using the traditional
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preprocessor.
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<ul>
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<li>Preprocessing directives are recognized only when their leading
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‘<samp><span class="samp">#</span></samp>’ appears in the first column. There can be no whitespace
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between the beginning of the line and the ‘<samp><span class="samp">#</span></samp>’, but whitespace can
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follow the ‘<samp><span class="samp">#</span></samp>’.
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<li>A true traditional C preprocessor does not recognize ‘<samp><span class="samp">#error</span></samp>’ or
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‘<samp><span class="samp">#pragma</span></samp>’, and may not recognize ‘<samp><span class="samp">#elif</span></samp>’. CPP supports all
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the directives in traditional mode that it supports in ISO mode,
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including extensions, with the exception that the effects of
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‘<samp><span class="samp">#pragma GCC poison</span></samp>’ are undefined.
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<li>__STDC__ is not defined.
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<li>If you use digraphs the behavior is undefined.
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<li>If a line that looks like a directive appears within macro arguments,
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the behavior is undefined.
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</ul>
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</body></html>
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