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<a name="clearerr_002c-clearerr_005funlocked_002d_002d_002dclear-file-or-stream-error-indicator"></a>
<h3 class="section">4.1 <code>clearerr</code>, <code>clearerr_unlocked</code>&mdash;clear file or stream error indicator</h3>
<a name="index-clearerr"></a>
<a name="index-clearerr_005funlocked"></a>
<p><strong>Synopsis</strong>
</p><div class="example">
<pre class="example">#include &lt;stdio.h&gt;
void clearerr(FILE *<var>fp</var>);

#define _BSD_SOURCE
#include &lt;stdio.h&gt;
void clearerr_unlocked(FILE *<var>fp</var>);

</pre></div>
<p><strong>Description</strong><br>
The <code>stdio</code> functions maintain an error indicator with each file
pointer <var>fp</var>, to record whether any read or write errors have
occurred on the associated file or stream.  Similarly, it maintains an
end-of-file indicator to record whether there is no more data in the
file.
</p>
<p>Use <code>clearerr</code> to reset both of these indicators.
</p>
<p>See <code>ferror</code> and <code>feof</code> to query the two indicators.
</p>
<p><code>clearerr_unlocked</code> is a non-thread-safe version of <code>clearerr</code>.
<code>clearerr_unlocked</code> may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile().  This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions.  If threads are disabled, then
<code>clearerr_unlocked</code> is equivalent to <code>clearerr</code>.
</p>
<br>
<p><strong>Returns</strong><br>
<code>clearerr</code> does not return a result.
</p>
<br>
<p><strong>Portability</strong><br>
ANSI C requires <code>clearerr</code>.
</p>
<p><code>clearerr_unlocked</code> is a BSD extension also provided by GNU libc.
</p>
<p>No supporting OS subroutines are required.
</p>
<br>


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