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108 lines
4.2 KiB
HTML
108 lines
4.2 KiB
HTML
4 years ago
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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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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<title>ferror (The Red Hat newlib C Library)</title>
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<meta name="description" content="ferror (The Red Hat newlib C Library)">
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<meta name="keywords" content="ferror (The Red Hat newlib C Library)">
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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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</head>
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<body lang="en">
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<a name="ferror"></a>
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<div class="header">
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<p>
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Next: <a href="fflush.html#fflush" accesskey="n" rel="next">fflush</a>, Previous: <a href="feof.html#feof" accesskey="p" rel="prev">feof</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="ferror_002c-ferror_005funlocked_002d_002d_002dtest-whether-read_002fwrite-error-has-occurred"></a>
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<h3 class="section">4.8 <code>ferror</code>, <code>ferror_unlocked</code>—test whether read/write error has occurred</h3>
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<a name="index-ferror"></a>
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<a name="index-ferror_005funlocked"></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 ferror(FILE *<var>fp</var>);
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#define _BSD_SOURCE
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#include <stdio.h>
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int ferror_unlocked(FILE *<var>fp</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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The <code>stdio</code> functions maintain an error indicator with each file
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pointer <var>fp</var>, to record whether any read or write errors have
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occurred on the associated file or stream.
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Use <code>ferror</code> to query this indicator.
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</p>
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<p>See <code>clearerr</code> to reset the error indicator.
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</p>
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<p><code>ferror_unlocked</code> is a non-thread-safe version of <code>ferror</code>.
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<code>ferror_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>ferror_unlocked</code> is equivalent to <code>ferror</code>.
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</p>
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<br>
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<p><strong>Returns</strong><br>
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<code>ferror</code> returns <code>0</code> if no errors have occurred; it returns a
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nonzero value otherwise.
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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>ferror</code>.
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</p>
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<p><code>ferror_unlocked</code> is a BSD extension also provided by GNU libc.
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</p>
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<p>No supporting OS subroutines are required.
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</p>
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<br>
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</body>
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</html>
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