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<title>Issue 566: array forms of unformatted input function undefined for zero-element arrays</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="566"><a href="lwg-defects.html#566">566</a>. array forms of unformatted input function undefined for zero-element arrays</h3>
<p><b>Section:</b> 31.7.5.4 <a href="https://wg21.link/istream.unformatted">[istream.unformatted]</a> <b>Status:</b> <a href="lwg-active.html#CD1">CD1</a>
 <b>Submitter:</b> Martin Sebor <b>Opened:</b> 2006-02-23 <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#istream.unformatted">issues</a> in [istream.unformatted].</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 array forms of unformatted input functions don't have well-defined
semantics for zero-element  arrays in a couple of  cases. The affected
ones (<code>istream::get()</code> and  <code>getline()</code>) are supposed to
terminate when <code>(n - 1)</code> characters are stored, which obviously
can never be true when <code>(n == 0)</code> to start with.

        </p>


<p id="res-566"><b>Proposed resolution:</b></p>
        <p>

I  propose  the following  changes  (references  are  relative to  the
Working Draft (document N1804).

        </p>
        <p>

Change 27.6.1.3, p8 (<code>istream::get()</code>), bullet 1 as follows:

        </p>
        <blockquote>
            <p>

<ins>if  <code>(n  &lt; 1)</code>  is  true  or  </ins> <code>(n  -  1)</code>
characters are stored;

            </p>
        </blockquote>
        <p>

Similarly, change  27.6.1.3, p18 (<code>istream::getline()</code>), bullet
3 as follows:

        </p>
        <blockquote>
            <p>

<ins><code>(n &lt; 1)</code> is  true or </ins><code>(n - 1)</code> characters
are     stored     (in    which     case     the    function     calls
<code>setstate(failbit)</code>).

            </p>
        </blockquote>
        <p>

Finally, change p21 as follows:

        </p>
        <blockquote>
            <p>

In any  case, <ins>provided  <code>(n &gt; 0)</code>  is true,  </ins>it then
stores  a null  character  (using charT())  into  the next  successive
location of the array.

            </p>
        </blockquote>





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