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<title>Issue 282: What types does numpunct grouping refer to?</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="282"><a href="lwg-defects.html#282">282</a>. What types does numpunct grouping refer to?</h3>
<p><b>Section:</b> 28.3.4.3.3.3 <a href="https://wg21.link/facet.num.put.virtuals">[facet.num.put.virtuals]</a> <b>Status:</b> <a href="lwg-active.html#CD1">CD1</a>
 <b>Submitter:</b> Howard Hinnant <b>Opened:</b> 2000-12-05 <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#facet.num.put.virtuals">active issues</a> in [facet.num.put.virtuals].</p>
<p><b>View all other</b> <a href="lwg-index.html#facet.num.put.virtuals">issues</a> in [facet.num.put.virtuals].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#CD1">CD1</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Paragraph 16 mistakenly singles out integral types for inserting 
thousands_sep() characters.  This conflicts with the syntax for floating 
point numbers described under 22.2.3.1/2.
</p>


<p id="res-282"><b>Proposed resolution:</b></p>
<p>Change paragraph 16 from:</p>

<blockquote><p>
For integral types, punct.thousands_sep() characters are inserted into 
the sequence as determined by the value returned by punct.do_grouping() 
using the method described in 28.3.4.4.1.3 <a href="https://wg21.link/facet.numpunct.virtuals">[facet.numpunct.virtuals]</a>.
</p></blockquote>

<p>To:</p>

<blockquote><p>
For arithmetic types, punct.thousands_sep() characters are inserted into 
the sequence as determined by the value returned by punct.do_grouping() 
using the method described in 28.3.4.4.1.3 <a href="https://wg21.link/facet.numpunct.virtuals">[facet.numpunct.virtuals]</a>.
</p></blockquote>

<p><i>[
Copenhagen: Opinions were divided about whether this is actually an
inconsistency, but at best it seems to have been unintentional.  This
is only an issue for floating-point output: The standard is
unambiguous that implementations must parse thousands_sep characters
when performing floating-point.  The standard is also unambiguous that
this requirement does not apply to the "C" locale.
]</i></p>


<p><i>[
A survey of existing practice is needed; it is believed that some
implementations do insert thousands_sep characters for floating-point
output and others fail to insert thousands_sep characters for 
floating-point input even though this is unambiguously required by the
standard.
]</i></p>


<p><i>[Post-Cura&ccedil;ao: the above proposed resolution is the consensus of
Howard, Bill, Pete, Benjamin, Nathan, Dietmar, Boris, and Martin.]</i></p>






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