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<title>Issue 573: C++0x file positioning should handle modern file sizes</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="573"><a href="lwg-closed.html#573">573</a>. C++0x file positioning should handle modern file sizes</h3>
<p><b>Section:</b> 31.5.3 <a href="https://wg21.link/fpos">[fpos]</a> <b>Status:</b> <a href="lwg-active.html#NAD">NAD</a>
 <b>Submitter:</b> Beman Dawes <b>Opened:</b> 2006-04-12 <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#fpos">issues</a> in [fpos].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD">NAD</a> status.</p>
<p><b>Discussion:</b></p>
<p>
There are two deficiencies related to file sizes:
</p>
<ol>
<li>It doesn't appear that the Standard Library is specified in
      a way that handles modern file sizes, which are often too
      large to be represented by an unsigned long.</li>

<li>The <code>std::fpos</code> class does not currently have the ability to
      set/get file positions.</li>
</ol>
<p>
The Dinkumware implementation of the Standard Library as shipped with the Microsoft compiler copes with these issues by:
</p>
<ol style="list-style-type:upper-alpha">
<li>Defining <code>fpos_t</code> be <code>long long</code>, which is large enough to
      represent any file position likely in the foreseeable future.</li>

<li>Adding member functions to class <code>fpos</code>. For example,
<blockquote><pre>
fpos_t seekpos() const;
</pre></blockquote>
</li>
</ol>
<p>
Because there are so many types relating to file positions and offsets (<code>fpos_t</code>,
<code>fpos</code>, <code>pos_type</code>, <code>off_type</code>, <code>streamoff</code>, <code>streamsize</code>, 
<code>streampos</code>, <code>wstreampos</code>, and perhaps more), it is difficult to know if 
the Dinkumware extensions are sufficient. But they seem a useful starting place for 
discussions, and they do represent existing practice.
</p>

<p><i>[
Kona (2007): We need a paper. It would be nice if someone proposed
clarifications to the definitions of <code>pos_type</code> and <code>off_type</code>. Currently
these definitions are horrible. Proposed Disposition: Open
]</i></p>


<p><i>[
2009-07 Frankfurt
]</i></p>


<blockquote>
<p>
This is the subject of paper N2926.
</p>
<p>
If we choose to take any action, we will move the paper, so the issue can be closed.
</p>
<p>
Move to NAD.
</p>
</blockquote>



<p id="res-573"><b>Proposed resolution:</b></p>
<p>
</p>





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