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<title>Issue 2270: Inconsistent to_string overloads</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#NAD">NAD</a> status.</em></p>
<h3 id="2270"><a href="lwg-closed.html#2270">2270</a>. Inconsistent <code>to_string</code> overloads</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#NAD">NAD</a>
 <b>Submitter:</b> Raf Schietekat <b>Opened:</b> 2013-07-02 <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#NAD">NAD</a> status.</p>
<p><b>Discussion:</b></p>
<p>
For internal consistency, <code>to_string()</code> should either list all relevant types (including <code>bool</code>, <code>char</code>, etc.), 
or only those that are the destination types of integral or floating-point promotion (<code>float</code> not being among them).
<p/>
A defensible reason for having (or rather keeping) the <code>float</code> overloads anyway could be to exactly mirror the adjacent 
sets of <code>stoX()</code> function overloads (even without round-trip fidelity for floating-point numbers).
<p/>
Unfortunately, that reveals a bigger issue than redundant overloads: the glaring and indefensible omission of an overloaded 
function <code>stoui()</code>. Adding that is not as trivial as removing redundant overloads, of course, because it requires 
everybody to take action. Still, it is the preferable remedy for the present situation.
<p/>
As far as I can tell from easily accessible information, C++ has already created the precedent with <code>stoi()</code>, which 
is not the equivalent of a pair of functions <code>strtoi()</code>/<code>wcstoi()</code> in C, but it would be if such functions 
existed. The function <code>atoi()</code> may look similar, but it does not qualify because it is as different from a 
hypothetical <code>strtoi()</code> as <code>atol()</code> currently is from <code>strtol()</code>, with the latter two both Standard C. 
It is only logical to act on this one-sided precedent by completing the set. Whether or not Standard C leads the way 
(or follows suit) is immaterial, but an invitation could be extended.
</p>

<p><i>[2013-09 Chicago]</i></p>

<p>
These overloads were very carefully and experimentally determined to be the minimal set, when all (known) promotion and
conversion scenarios were considered.  Removing superfluous-looking overloads is likely to result in ambiguities.
</p>



<p id="res-2270"><b>Proposed resolution:</b></p>

<p>This wording is relative to N3691.</p>

<ol>
<li><p>Modify 27.4 <a href="https://wg21.link/string.classes">[string.classes]</a>, header <code>&lt;string&gt;</code> synopsis, as indicated:</p>

<blockquote><pre>
#include &lt;initializer_list&gt;

namespace std {
  [&hellip;]
  string to_string(int val);
  string to_string(unsigned val);
  string to_string(long val);
  string to_string(unsigned long val);
  string to_string(long long val);
  string to_string(unsigned long long val);
  <del>string to_string(float val);</del>
  string to_string(double val);
  string to_string(long double val);
  [&hellip;]

  [&hellip;]
  wstring to_wstring(int val);
  wstring to_wstring(unsigned val);
  wstring to_wstring(long val);
  wstring to_wstring(unsigned long val);
  wstring to_wstring(long long val);
  wstring to_wstring(unsigned long long val);
  <del>wstring to_wstring(float val);</del>
  wstring to_wstring(double val);
  wstring to_wstring(long double val);
  [&hellip;]
}
</pre></blockquote>
</li>

<li><p>Modify 27.4.5 <a href="https://wg21.link/string.conversions">[string.conversions]</a> p7+14 as indicated:</p>

<blockquote>
<pre>
string to_string(int val);
string to_string(unsigned val);
string to_string(long val);
string to_string(unsigned long val);
string to_string(long long val);
string to_string(unsigned long long val);
<del>string to_string(float val);</del>
string to_string(double val);
string to_string(long double val);
</pre>
<blockquote>
<p>
-7- <i>Returns:</i> Each function returns a <code>string</code> 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 of
<code>"%d"</code>, <code>"%u"</code>, <code>"%ld"</code>, <code>"%lu"</code>, <code>"%lld"</code>, <code>"%llu"</code>, <del><code>"%f"</code>,</del> 
<code>"%f"</code>, or <code>"%Lf"</code>, respectively, where <code>buf</code> designates an internal character buffer of sufficient size.
<p/>
[&hellip;]
</p>
</blockquote>
<pre>
wstring to_wstring(int val);
wstring to_wstring(unsigned val);
wstring to_wstring(long val);
wstring to_wstring(unsigned long val);
wstring to_wstring(long long val);
wstring to_wstring(unsigned long long val);
<del>wstring to_wstring(float val);</del>
wstring to_wstring(double val);
wstring to_wstring(long double val);
</pre>
<blockquote>
<p>
-14- <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>swprintf(buf, buffsz, fmt, val)</code> with a format specifier of
<code>L"%d"</code>, <code>L"%u"</code>, <code>L"%ld"</code>, <code>L"%lu"</code>, <code>L"%lld"</code>, <code>L"%llu"</code>, <del><code>L"%f"</code>,</del> 
<code>L"%f"</code>, or <code>L"%Lf"</code>, respectively, where <code>buf</code> designates an internal character buffer of sufficient 
size <code>buffsz</code>.
</p>
</blockquote>
</blockquote>
</li>
</ol>






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