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<title>Issue 136: seekp, seekg setting wrong streams?</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#CD1">CD1</a> status.</em></p>
<h3 id="136"><a href="lwg-defects.html#136">136</a>. seekp, seekg setting wrong streams?</h3>
<p><b>Section:</b> 31.7.5.4 <a href="https://wg21.link/istream.unformatted">[istream.unformatted]</a> <b>Status:</b> <a href="lwg-active.html#CD1">CD1</a>
 <b>Submitter:</b> Howard Hinnant <b>Opened:</b> 1999-03-06 <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#istream.unformatted">issues</a> in [istream.unformatted].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#CD1">CD1</a> status.</p>
<p><b>Discussion:</b></p>
<p>I may be misunderstanding the intent, but should not seekg set only
the input stream and seekp set only the output stream? The description
seems to say that each should set both input and output streams. If
that's really the intent, I withdraw this proposal.</p>


<p id="res-136"><b>Proposed resolution:</b></p>
<p>In section 27.6.1.3 change:</p>

<pre>basic_istream&lt;charT,traits&gt;&amp; seekg(pos_type pos);
Effects: If fail() != true, executes rdbuf()-&gt;pubseekpos(pos). </pre>

<p>To:</p>

<pre>basic_istream&lt;charT,traits&gt;&amp; seekg(pos_type pos);
Effects: If fail() != true, executes rdbuf()-&gt;pubseekpos(pos, ios_base::in). </pre>

<p>In section 27.6.1.3 change:</p>

<pre>basic_istream&lt;charT,traits&gt;&amp; seekg(off_type&amp; off, ios_base::seekdir dir);
Effects: If fail() != true, executes rdbuf()-&gt;pubseekoff(off, dir). </pre>

<p>To:</p>

<pre>basic_istream&lt;charT,traits&gt;&amp; seekg(off_type&amp; off, ios_base::seekdir dir);
Effects: If fail() != true, executes rdbuf()-&gt;pubseekoff(off, dir, ios_base::in). </pre>

<p>In section 27.6.2.4, paragraph 2 change:</p>

<pre>-2- Effects: If fail() != true, executes rdbuf()-&gt;pubseekpos(pos). </pre>

<p>To:</p>

<pre>-2- Effects: If fail() != true, executes rdbuf()-&gt;pubseekpos(pos, ios_base::out). </pre>

<p>In section 27.6.2.4, paragraph 4 change:</p>

<pre>-4- Effects: If fail() != true, executes rdbuf()-&gt;pubseekoff(off, dir). </pre>

<p>To:</p>

<pre>-4- Effects: If fail() != true, executes rdbuf()-&gt;pubseekoff(off, dir, ios_base::out). </pre>

<p><i>[Dublin: Dietmar K&uuml;hl thinks this is probably correct, but would
like the opinion of more iostream experts before taking action.]</i></p>


<p><i>[Tokyo: Reviewed by the LWG. PJP noted that although his docs are
incorrect, his implementation already implements the Proposed
Resolution.]</i></p>


<p><i>[Post-Tokyo: Matt Austern comments:<br/>
Is it a problem with basic_istream and basic_ostream, or is it a problem
with basic_stringbuf?
We could resolve the issue either by changing basic_istream and
basic_ostream, or by changing basic_stringbuf. I prefer the latter
change (or maybe both changes): I don't see any reason for the standard to
require that std::stringbuf s(std::string(&quot;foo&quot;), std::ios_base::in);
s.pubseekoff(0, std::ios_base::beg); must fail.<br/>
This requirement is a bit weird. There's no similar requirement
for basic_streambuf&lt;&gt;::seekpos, or for basic_filebuf&lt;&gt;::seekoff or
basic_filebuf&lt;&gt;::seekpos.]</i></p>






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