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127 lines
5.6 KiB
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127 lines
5.6 KiB
HTML
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<a name="fgets"></a>
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<div class="header">
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<p>
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Next: <a href="fgetwc.html#fgetwc" accesskey="n" rel="next">fgetwc</a>, Previous: <a href="fgetpos.html#fgetpos" accesskey="p" rel="prev">fgetpos</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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<hr>
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<a name="fgets_002c-fgets_005funlocked_002d_002d_002dget-character-string-from-a-file-or-stream"></a>
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<h3 class="section">4.12 <code>fgets</code>, <code>fgets_unlocked</code>—get character string from a file or stream</h3>
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<a name="index-fgets"></a>
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<a name="index-fgets_005funlocked"></a>
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<a name="index-_005ffgets_005fr"></a>
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<a name="index-_005ffgets_005funlocked_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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char *fgets(char *restrict <var>buf</var>, int <var>n</var>, FILE *restrict <var>fp</var>);
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#define _GNU_SOURCE
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#include <stdio.h>
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char *fgets_unlocked(char *restrict <var>buf</var>, int <var>n</var>, FILE *restrict <var>fp</var>);
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#include <stdio.h>
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char *_fgets_r(struct _reent *<var>ptr</var>, char *restrict <var>buf</var>, int <var>n</var>, FILE *restrict <var>fp</var>);
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#include <stdio.h>
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char *_fgets_unlocked_r(struct _reent *<var>ptr</var>, char *restrict <var>buf</var>, int <var>n</var>, FILE *restrict <var>fp</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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Reads at most <var>n-1</var> characters from <var>fp</var> until a newline
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is found. The characters including to the newline are stored
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in <var>buf</var>. The buffer is terminated with a 0.
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</p>
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<p><code>fgets_unlocked</code> is a non-thread-safe version of <code>fgets</code>.
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<code>fgets_unlocked</code> may only safely be used within a scope
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protected by flockfile() (or ftrylockfile()) and funlockfile(). This
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function may safely be used in a multi-threaded program if and only
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if they are called while the invoking thread owns the (FILE *)
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object, as is the case after a successful call to the flockfile() or
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ftrylockfile() functions. If threads are disabled, then
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<code>fgets_unlocked</code> is equivalent to <code>fgets</code>.
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</p>
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<p>The functions <code>_fgets_r</code> and <code>_fgets_unlocked_r</code> are simply
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reentrant versions that are passed the additional reentrant structure
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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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<code>fgets</code> returns the buffer passed to it, with the data
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filled in. If end of file occurs with some data already
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accumulated, the data is returned with no other indication. If
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no data are read, NULL is returned instead.
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</p>
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<br>
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<p><strong>Portability</strong><br>
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<code>fgets</code> should replace all uses of <code>gets</code>. Note however
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that <code>fgets</code> returns all of the data, while <code>gets</code> removes
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the trailing newline (with no indication that it has done so.)
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</p>
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<p><code>fgets_unlocked</code> is a GNU extension.
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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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<hr>
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<div class="header">
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<p>
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Next: <a href="fgetwc.html#fgetwc" accesskey="n" rel="next">fgetwc</a>, Previous: <a href="fgetpos.html#fgetpos" accesskey="p" rel="prev">fgetpos</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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