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fail [C++ Reference]
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<h2><a name="fail" id="fail">fail</a></h2>
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<p>
Syntax:
</p>
<pre class="c code c++" style="font-family:monospace;"> bool stream<span class="sy0">::</span><span class="me2">fail</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span></pre>
<p>
The fail() function returns true if an error has occurred with the current
stream, false otherwise. This can be used for checking whether the previous operation has failed.
</p>
<p>
Examples of failures that cause fail to be set:
</p>
<ul>
<li class="level1"><div class="li">file not found (when opening for reading).</div>
</li>
<li class="level1"><div class="li">file cannot be created (when opening for writing).</div>
</li>
<li class="level1"><div class="li">end of file is reached before the requested data could be read.</div>
</li>
<li class="level1"><div class="li">invalid formatting of data (e.g. letters when expecting numbers).</div>
</li>
</ul>
<p>
Once set, the fail state will make all other operations on the stream fail instantly, until the error state is cleared with the clear function.
</p>
<p>
Related Topics: <a href="../io/bad.html" class="wikilink1" title="io:bad">bad</a>, <a href="../io/clear.html" class="wikilink1" title="io:clear">clear</a>, <a href="../io/eof.html" class="wikilink1" title="io:eof">eof</a>, <a href="../io/exceptions.html" class="wikilink1" title="io:exceptions">exceptions</a>, <a href="../io/good.html" class="wikilink1" title="io:good">good</a>, <a href="../io/rdstate.html" class="wikilink1" title="io:rdstate">rdstate</a>
</p>
<p>
Stream states:
</p>
<ul>
<li class="level1"><div class="li">if (s): The previous operation was successful (a shorthand for !s.fail()).</div>
</li>
<li class="level1"><div class="li">if (s.fail()): The previous operation failed.</div>
</li>
<li class="level1"><div class="li">if (s.eof()): Reading past the end has been attempted.</div>
</li>
<li class="level1"><div class="li">if (s.bad()): Stream state is undefined; the stream can no longer be used.</div>
</li>
<li class="level1"><div class="li">if (s.good()): None of bad/eof/fail are set.</div>
</li>
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