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<title>Issue 534: Missing basic_string members</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="534"><a href="lwg-defects.html#534">534</a>. Missing basic_string members</h3>
<p><b>Section:</b> 27.4.3 <a href="https://wg21.link/basic.string">[basic.string]</a> <b>Status:</b> <a href="lwg-active.html#CD1">CD1</a>
 <b>Submitter:</b> Alisdair Meredith <b>Opened:</b> 2005-11-16 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View other</b> <a href="lwg-index-open.html#basic.string">active issues</a> in [basic.string].</p>
<p><b>View all other</b> <a href="lwg-index.html#basic.string">issues</a> in [basic.string].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#CD1">CD1</a> status.</p>
<p><b>Discussion:</b></p>
<p>
OK, we all know std::basic_string is bloated and already has way too
many members.  However, I propose it is missing 3 useful members that
are often expected by users believing it is a close approximation of the
container concept.  All 3 are listed in table 71 as 'optional'
</p>

<p>
i/  pop_back.
</p>

<p>
This is the one I feel most strongly about, as I only just discovered it
was missing as we are switching to a more conforming standard library
&lt;g&gt;
</p>

<p>
I find it particularly inconsistent to support push_back, but not
pop_back.
</p>

<p>
ii/ back.
</p>

<p>
There are certainly cases where I want to examine the last character of
a string before deciding to append, or to trim trailing path separators
from directory names etc.  *rbegin() somehow feels inelegant.
</p>

<p>
iii/ front
</p>

<p>
This one I don't feel strongly about, but if I can get the first two,
this one feels that it should be added as a 'me too' for consistency.
</p>

<p>
I believe this would be similarly useful to the data() member recently
added to vector, or at() member added to the maps.
</p>


<p id="res-534"><b>Proposed resolution:</b></p>
<p>
Add the following members to definition of class template basic_string, 21.3p7
</p>
<blockquote><pre>
void pop_back ()

const charT &amp; front() const
charT &amp; front()

const charT &amp; back() const
charT &amp; back()
</pre></blockquote>
<p>
Add the following paragraphs to basic_string description
</p>

<p>
21.3.4p5
</p>
<blockquote>
<pre>
const charT &amp; front() const
charT &amp; front()
</pre>
<p>
<i>Precondition:</i> <code>!empty()</code>
</p>
<p>
<i>Effects:</i> Equivalent to <code>operator[](0)</code>.
</p>
</blockquote>

<p>
21.3.4p6
</p>
<blockquote>
<pre>
const charT &amp; back() const
charT &amp; back()
</pre>
<p>
<i>Precondition:</i> <code>!empty()</code>
</p>
<p>
<i>Effects:</i> Equivalent to <code>operator[]( size() - 1)</code>.
</p>
</blockquote>

<p>
21.3.5.5p10
</p>
<blockquote>
<pre>
void pop_back ()
</pre>
<p>
<i>Precondition:</i> <code>!empty()</code>
</p>
<p>
<i>Effects:</i> Equivalent to <code>erase( size() - 1, 1 )</code>.
</p>
</blockquote>

<p>
Update Table 71: (optional sequence operations)
Add basic_string to the list of containers for the following operations.
</p>
<blockquote><pre>
a.front()
a.back()
a.push_back()
a.pop_back()
a[n]
</pre></blockquote>

<p><i>[
Berlin: Has support.  Alisdair provided wording.
]</i></p>






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