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<a name="qsort_002d_002d_002dsort-an-array"></a>
<h3 class="section">2.32 <code>qsort</code>&mdash;sort an array</h3>
<a name="index-qsort"></a>
<p><strong>Synopsis</strong>
</p><div class="example">
<pre class="example">#include &lt;stdlib.h&gt;
void qsort(void *<var>base</var>, size_t <var>nmemb</var>, size_t <var>size</var>,
    int (*<var>compar</var>)(const void *, const void *) );

</pre></div>
<p><strong>Description</strong><br>
<code>qsort</code> sorts an array (beginning at <var>base</var>) of <var>nmemb</var> objects.
<var>size</var> describes the size of each element of the array.
</p>
<p>You must supply a pointer to a comparison function, using the argument
shown as <var>compar</var>.  (This permits sorting objects of unknown
properties.)  Define the comparison function to accept two arguments,
each a pointer to an element of the array starting at <var>base</var>.  The
result of <code>(*<var>compar</var>)</code> must be negative if the first argument is
less than the second, zero if the two arguments match, and positive if
the first argument is greater than the second (where &ldquo;less than&rdquo; and
&ldquo;greater than&rdquo; refer to whatever arbitrary ordering is appropriate).
</p>
<p>The array is sorted in place; that is, when <code>qsort</code> returns, the
array elements beginning at <var>base</var> have been reordered.
</p>
<br>
<p><strong>Returns</strong><br>
<code>qsort</code> does not return a result.
</p>
<br>
<p><strong>Portability</strong><br>
<code>qsort</code> is required by ANSI (without specifying the sorting algorithm).
</p>
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