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108 lines
4.5 KiB
HTML
108 lines
4.5 KiB
HTML
4 years ago
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<title>getc (The Red Hat newlib C Library)</title>
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<meta name="description" content="getc (The Red Hat newlib C Library)">
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<meta name="keywords" content="getc (The Red Hat newlib C Library)">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Document-Index.html#Document-Index" rel="index" title="Document Index">
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<link href="Document-Index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Stdio.html#Stdio" rel="up" title="Stdio">
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<link href="getc_005funlocked.html#getc_005funlocked" rel="next" title="getc_unlocked">
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</head>
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<body lang="en">
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<a name="getc"></a>
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<div class="header">
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<p>
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Next: <a href="getc_005funlocked.html#getc_005funlocked" accesskey="n" rel="next">getc_unlocked</a>, Previous: <a href="fwrite.html#fwrite" accesskey="p" rel="prev">fwrite</a>, Up: <a href="Stdio.html#Stdio" accesskey="u" rel="up">Stdio</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="getc_002d_002d_002dread-a-character-_0028macro_0029"></a>
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<h3 class="section">4.33 <code>getc</code>—read a character (macro)</h3>
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<a name="index-getc"></a>
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<a name="index-_005fgetc_005fr"></a>
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<p><strong>Synopsis</strong>
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</p><div class="example">
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<pre class="example">#include <stdio.h>
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int getc(FILE *<var>fp</var>);
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#include <stdio.h>
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int _getc_r(struct _reent *<var>ptr</var>, FILE *<var>fp</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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<code>getc</code> is a macro, defined in <code>stdio.h</code>. You can use <code>getc</code>
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to get the next single character from the file or stream
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identified by <var>fp</var>. As a side effect, <code>getc</code> advances the file’s
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current position indicator.
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</p>
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<p>For a subroutine version of this macro, see <code>fgetc</code>.
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</p>
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<p>The <code>_getc_r</code> function is simply the reentrant version of <code>getc</code>
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which passes an additional reentrancy structure pointer argument: <var>ptr</var>.
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</p>
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<br>
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<p><strong>Returns</strong><br>
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The next character (read as an <code>unsigned char</code>, and cast to
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<code>int</code>), unless there is no more data, or the host system reports a
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read error; in either of these situations, <code>getc</code> returns <code>EOF</code>.
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</p>
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<p>You can distinguish the two situations that cause an <code>EOF</code> result by
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using the <code>ferror</code> and <code>feof</code> functions.
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</p>
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<br>
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<p><strong>Portability</strong><br>
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ANSI C requires <code>getc</code>; it suggests, but does not require, that
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<code>getc</code> be implemented as a macro. The standard explicitly permits
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macro implementations of <code>getc</code> to use the argument more than once;
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therefore, in a portable program, you should not use an expression
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with side effects as the <code>getc</code> argument.
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</p>
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<p>Supporting OS subroutines required: <code>close</code>, <code>fstat</code>, <code>isatty</code>,
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<code>lseek</code>, <code>read</code>, <code>sbrk</code>, <code>write</code>.
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</p>
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<br>
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</body>
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</html>
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