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<title>The GNU Fortran Compiler: COUNT</title>

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<a name="COUNT-_002d_002d_002d-Count-function"></a>
<h3 class="section">9.78 <code>COUNT</code> &mdash; Count function</h3>
<a name="index-COUNT"></a>
<a name="index-array_002c-conditionally-count-elements"></a>
<a name="index-array_002c-element-counting"></a>
<a name="index-array_002c-number-of-elements"></a>

<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd>
<p>Counts the number of <code>.TRUE.</code> elements in a logical <var>MASK</var>,
or, if the <var>DIM</var> argument is supplied, counts the number of
elements along each row of the array in the <var>DIM</var> direction.
If the array has zero size, or all of the elements of <var>MASK</var> are
<code>.FALSE.</code>, then the result is <code>0</code>.
</p>
</dd>
<dt><em>Standard</em>:</dt>
<dd><p>Fortran 95 and later, with <var>KIND</var> argument Fortran 2003 and later
</p>
</dd>
<dt><em>Class</em>:</dt>
<dd><p>Transformational function
</p>
</dd>
<dt><em>Syntax</em>:</dt>
<dd><p><code>RESULT = COUNT(MASK [, DIM, KIND])</code>
</p>
</dd>
<dt><em>Arguments</em>:</dt>
<dd><table>
<tr><td width="15%"><var>MASK</var></td><td width="70%">The type shall be <code>LOGICAL</code>.</td></tr>
<tr><td width="15%"><var>DIM</var></td><td width="70%">(Optional) The type shall be <code>INTEGER</code>.</td></tr>
<tr><td width="15%"><var>KIND</var></td><td width="70%">(Optional) An <code>INTEGER</code> initialization
expression indicating the kind parameter of the result.</td></tr>
</table>

</dd>
<dt><em>Return value</em>:</dt>
<dd><p>The return value is of type <code>INTEGER</code> and of kind <var>KIND</var>. If
<var>KIND</var> is absent, the return value is of default integer kind.
If <var>DIM</var> is present, the result is an array with a rank one less
than the rank of <var>ARRAY</var>, and a size corresponding to the shape
of <var>ARRAY</var> with the <var>DIM</var> dimension removed.
</p>
</dd>
<dt><em>Example</em>:</dt>
<dd><div class="smallexample">
<pre class="smallexample">program test_count
    integer, dimension(2,3) :: a, b
    logical, dimension(2,3) :: mask
    a = reshape( (/ 1, 2, 3, 4, 5, 6 /), (/ 2, 3 /))
    b = reshape( (/ 0, 7, 3, 4, 5, 8 /), (/ 2, 3 /))
    print '(3i3)', a(1,:)
    print '(3i3)', a(2,:)
    print *
    print '(3i3)', b(1,:)
    print '(3i3)', b(2,:)
    print *
    mask = a.ne.b
    print '(3l3)', mask(1,:)
    print '(3l3)', mask(2,:)
    print *
    print '(3i3)', count(mask)
    print *
    print '(3i3)', count(mask, 1)
    print *
    print '(3i3)', count(mask, 2)
end program test_count
</pre></div>
</dd>
</dl>


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