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fflush [C++ Reference]
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<span class="bchead">You are here: </span><a href="../../start.html" title="start">C++ Reference</a> » <a href="../../c/start.html" title="c:start">The Standard C Library</a> » <a href="../../c/io/start.html" title="c:io:start">Standard C I/O</a> » <a href="../../c/io/fflush.html" title="c:io:fflush">fflush</a> </div>
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<h2><a name="fflush" id="fflush">fflush</a></h2>
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<p>
Syntax:
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<pre class="c code c++" style="font-family:monospace;"> <span class="co2">#include <cstdio></span>
<span class="kw4">int</span> fflush<span class="br0">(</span> FILE <span class="sy0">*</span>stream <span class="br0">)</span><span class="sy0">;</span></pre>
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If the given file stream is an output stream, then fflush() causes the output buffer to be written to the file.
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<p>
If the given stream is of the input type, then the behavior of fflush() is undefined.
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<p>
fflush() is useful when debugging, if a program segfaults before it has a chance to write output to the screen. Calling fflush(stdout) directly after debugging output will ensure that your output is displayed at the correct time.
</p>
<pre class="c code c++" style="font-family:monospace;"> <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html"><span class="kw3">printf</span></a><span class="br0">(</span> <span class="st0">"Before first call<span class="es1">\n</span>"</span> <span class="br0">)</span><span class="sy0">;</span>
fflush<span class="br0">(</span> stdout <span class="br0">)</span><span class="sy0">;</span>
shady_function<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span>
fflush<span class="br0">(</span> stdout <span class="br0">)</span><span class="sy0">;</span>
dangerous_dereference<span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span></pre>
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Related Topics: <a href="../../c/io/fclose.html" class="wikilink1" title="c:io:fclose">fclose</a>, <a href="../../c/io/fopen.html" class="wikilink1" title="c:io:fopen">fopen</a>, <a href="../../c/io/fread.html" class="wikilink1" title="c:io:fread">fread</a>, <a href="../../c/io/fpurge.html" class="wikilink1" title="c:io:fpurge">fpurge</a>, <a href="../../c/io/fwrite.html" class="wikilink1" title="c:io:fwrite">fwrite</a>, <a href="../../c/io/getc.html" class="wikilink1" title="c:io:getc">getc</a>, <a href="../../c/io/putc.html" class="wikilink1" title="c:io:putc">putc</a>
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