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<title>Issue 772: Impossible return clause in [string.conversions]</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="772"><a href="lwg-defects.html#772">772</a>. Impossible return clause in [string.conversions]</h3>
<p><b>Section:</b> 27.4.5 <a href="https://wg21.link/string.conversions">[string.conversions]</a> <b>Status:</b> <a href="lwg-active.html#CD1">CD1</a>
 <b>Submitter:</b> Daniel Kr&uuml;gler <b>Opened:</b> 2008-01-13 <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#string.conversions">issues</a> in [string.conversions].</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 return clause 27.4.5 <a href="https://wg21.link/string.conversions">[string.conversions]</a> paragraph 15 of the new <code>to_wstring</code>
overloads says:
</p>

<blockquote><p>
<i>Returns:</i> each function returns a <code>wstring</code> object holding the character
representation of the value of its argument that would be generated by
calling <code>wsprintf(buf, fmt, val)</code> with a format specifier of <code>L"%lld"</code>, <code>L"%ulld"</code>,
or <code>L"%f"</code>, respectively.
</p></blockquote>

<p>
Problem is: There does not exist any <code>wsprintf</code> function in C99 (I checked
the 2nd edition of ISO 9899, and the first and the second corrigenda from
2001-09-01 and 2004-11-15). What probably meant here is the function
<code>swprintf</code> from <code>&lt;wchar.h&gt;&#47;&lt;cwchar&gt;</code>, but this has the non-equivalent
declaration:
</p>

<blockquote><pre>
int swprintf(wchar_t * restrict s, size_t n,
const wchar_t * restrict format, ...);
</pre></blockquote>

<p>
therefore the paragraph needs to mention the <code>size_t</code> parameter <code>n</code>.
</p>



<p id="res-772"><b>Proposed resolution:</b></p>
<p>
Change the current wording of 27.4.5 <a href="https://wg21.link/string.conversions">[string.conversions]</a> p. 15 to:
</p>

<blockquote><p>
<i>Returns:</i> <del>e</del><ins>E</ins>ach function returns a
<code>wstring</code> object holding the character representation of the
value of its argument that would be generated by calling
<code><del>ws</del><ins>sw</ins>printf(buf, <ins>bufsz,</ins> fmt,
val)</code> with a format specifier <ins><code>fmt</code></ins> of <code>L"%lld"</code>,
<code>L"%ulld"</code>, or <code>L"%f"</code>, respectively<ins>, where <code>buf</code>
designates an internal character buffer of sufficient size <code>bufsz</code></ins>.
</p></blockquote>

<p>
[Hint to the editor: The resolution also adds to mention the name of
the format specifier "fmt"]
</p>

<p>
I also would like to remark that the current wording of it's equivalent
paragraph 7 should also mention the meaning of <code>buf</code> and <code>fmt</code>.
</p>

<p>
Change the current wording of 27.4.5 <a href="https://wg21.link/string.conversions">[string.conversions]</a> p. 7 to:
</p>

<blockquote><p>
<i>Returns:</i> <del>e</del><ins>E</ins>ach function returns a string object holding the
character representation of the value of its argument that would be
generated by calling <code>sprintf(buf, fmt, val)</code> with a format specifier <ins><code>fmt</code></ins> of
<code>"%lld"</code>, <code>"%ulld"</code>, or <code>"%f"</code>, respectively<ins>, where <code>buf</code> designates an internal
character buffer of sufficient size</ins>.
</p></blockquote>






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