106 lines
4.6 KiB
HTML
106 lines
4.6 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1987-2016 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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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>The C Preprocessor: Other Directives</title>
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<meta name="description" content="The C Preprocessor: Other Directives">
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<meta name="keywords" content="The C Preprocessor: Other Directives">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Index-of-Directives.html#Index-of-Directives" rel="index" title="Index of Directives">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="index.html#Top" rel="up" title="Top">
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<link href="Preprocessor-Output.html#Preprocessor-Output" rel="next" title="Preprocessor Output">
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<link href="Pragmas.html#Pragmas" rel="prev" title="Pragmas">
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<style type="text/css">
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-->
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</style>
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Other-Directives"></a>
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<div class="header">
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<p>
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Next: <a href="Preprocessor-Output.html#Preprocessor-Output" accesskey="n" rel="next">Preprocessor Output</a>, Previous: <a href="Pragmas.html#Pragmas" accesskey="p" rel="prev">Pragmas</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html#Index-of-Directives" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Other-Directives-1"></a>
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<h2 class="chapter">8 Other Directives</h2>
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<a name="index-_0023ident"></a>
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<a name="index-_0023sccs"></a>
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<p>The ‘<samp>#ident</samp>’ directive takes one argument, a string constant. On
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some systems, that string constant is copied into a special segment of
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the object file. On other systems, the directive is ignored. The
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‘<samp>#sccs</samp>’ directive is a synonym for ‘<samp>#ident</samp>’.
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</p>
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<p>These directives are not part of the C standard, but they are not
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official GNU extensions either. What historical information we have
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been able to find, suggests they originated with System V.
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</p>
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<a name="index-null-directive"></a>
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<p>The <em>null directive</em> consists of a ‘<samp>#</samp>’ followed by a newline,
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with only whitespace (including comments) in between. A null directive
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is understood as a preprocessing directive but has no effect on the
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preprocessor output. The primary significance of the existence of the
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null directive is that an input line consisting of just a ‘<samp>#</samp>’ will
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produce no output, rather than a line of output containing just a
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‘<samp>#</samp>’. Supposedly some old C programs contain such lines.
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</p>
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</body>
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</html>
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