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<title>Issue 691: const_local_iterator cbegin, cend missing from TR1</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="691"><a href="lwg-defects.html#691">691</a>. const_local_iterator cbegin, cend missing from TR1</h3>
<p><b>Section:</b> 23.5 <a href="https://wg21.link/unord">[unord]</a>, 99 [tr.hash] <b>Status:</b> <a href="lwg-active.html#CD1">CD1</a>
 <b>Submitter:</b> Joaqu&iacute;n M L&oacute;pez Mu&ntilde;oz <b>Opened:</b> 2007-06-14 <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#unord">issues</a> in [unord].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#CD1">CD1</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The last version of TR1 does not include the following member
functions
for unordered containers:
</p>

<blockquote><pre>
const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;
</pre></blockquote>

<p>
which looks like an oversight to me. I've checked th TR1 issues lists
and the latest working draft of the C++0x std (N2284) and haven't
found any mention to these menfuns or to their absence.
</p>
<p>
Is this really an oversight, or am I missing something?
</p>



<p id="res-691"><b>Proposed resolution:</b></p>
<p>
Add the following two rows to table 93 (unordered associative container
requirements) in section 23.2.8 <a href="https://wg21.link/unord.req">[unord.req]</a>:
</p>

<blockquote>
<table border="1">
<caption>Unordered associative container requirements (in addition to container)</caption>
<tr>
<th>expression</th> <th>return type</th> <th>assertion/note pre/post-condition</th> <th>complexity</th>
</tr>
<tr>
<td><ins><code>b.cbegin(n)</code></ins></td> <td><ins><code>const_local_iterator</code></ins></td> <td><ins><code>n</code> shall be in the range <code>[0, bucket_count())</code>. Note: <code>[b.cbegin(n), b.cend(n))</code> is a valid range containing all of the elements in the <code>n</code><sup><i>th</i></sup> bucket.</ins></td> <td><ins>Constant</ins></td> 
</tr>
<tr>
<td><ins><code>b.cend(n)</code></ins></td> <td><ins><code>const_local_iterator</code></ins></td> <td><ins><code>n</code> shall be in the range <code>[0, bucket_count())</code>.</ins></td> <td><ins>Constant</ins></td> 
</tr>
</table>
</blockquote>

<p>
Add to the synopsis in 23.5.3 <a href="https://wg21.link/unord.map">[unord.map]</a>:
</p>

<blockquote><pre>
<ins>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;</ins>
</pre></blockquote>

<p>
Add to the synopsis in 23.5.4 <a href="https://wg21.link/unord.multimap">[unord.multimap]</a>:
</p>

<blockquote><pre>
<ins>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;</ins>
</pre></blockquote>

<p>
Add to the synopsis in 23.5.6 <a href="https://wg21.link/unord.set">[unord.set]</a>:
</p>

<blockquote><pre>
<ins>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;</ins>
</pre></blockquote>

<p>
Add to the synopsis in 23.5.7 <a href="https://wg21.link/unord.multiset">[unord.multiset]</a>:
</p>

<blockquote><pre>
<ins>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;</ins>
</pre></blockquote>






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