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<title>Issue 158: Underspecified semantics for setbuf()</title>
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<p><em>This page is a snapshot from the LWG issues list, see the <a href="lwg-active.html">Library Active Issues List</a> for more information and the meaning of <a href="lwg-active.html#TC1">TC1</a> status.</em></p>
<h3 id="158"><a href="lwg-defects.html#158">158</a>. Underspecified semantics for <code>setbuf()</code></h3>
<p><b>Section:</b> 31.6.3.5.2 <a href="https://wg21.link/streambuf.virt.buffer">[streambuf.virt.buffer]</a> <b>Status:</b> <a href="lwg-active.html#TC1">TC1</a>
 <b>Submitter:</b> Dietmar K&uuml;hl <b>Opened:</b> 1999-07-20 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#streambuf.virt.buffer">issues</a> in [streambuf.virt.buffer].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#TC1">TC1</a> status.</p>
<p><b>Discussion:</b></p>
<p>The default behavior of <code>setbuf()</code> is described only for the
situation that <code>gptr() != 0 &amp;&amp; gptr() != egptr()</code>:
namely to do nothing.  What has to be done in other situations&nbsp;
is not described although there is actually only one reasonable
approach, namely to do nothing, too.</p> 

<p>Since changing the buffer would almost certainly mess up most
buffer management of derived classes unless these classes do it
themselves, the default behavior of <code>setbuf()</code> should always be
to do nothing.</p>


<p id="res-158"><b>Proposed resolution:</b></p>
<p>Change 31.6.3.5.2 <a href="https://wg21.link/streambuf.virt.buffer">[streambuf.virt.buffer]</a>, paragraph 3, Default behavior,
to: &quot;Default behavior: Does nothing. Returns this.&quot;</p>




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