toolchain/gcc-linaro-6.3.1-2017.02-x8.../share/doc/gfortran/ASSOCIATED.html

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<a name="ASSOCIATED-_002d_002d_002d-Status-of-a-pointer-or-pointer_002ftarget-pair"></a>
<h3 class="section">9.20 <code>ASSOCIATED</code> &mdash; Status of a pointer or pointer/target pair</h3>
<a name="index-ASSOCIATED"></a>
<a name="index-pointer_002c-status"></a>
<a name="index-association-status"></a>

<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p><code>ASSOCIATED(POINTER [, TARGET])</code> determines the status of the pointer
<var>POINTER</var> or if <var>POINTER</var> is associated with the target <var>TARGET</var>.
</p>
</dd>
<dt><em>Standard</em>:</dt>
<dd><p>Fortran 95 and later
</p>
</dd>
<dt><em>Class</em>:</dt>
<dd><p>Inquiry function
</p>
</dd>
<dt><em>Syntax</em>:</dt>
<dd><p><code>RESULT = ASSOCIATED(POINTER [, TARGET])</code>
</p>
</dd>
<dt><em>Arguments</em>:</dt>
<dd><table>
<tr><td width="15%"><var>POINTER</var></td><td width="70%"><var>POINTER</var> shall have the <code>POINTER</code> attribute
and it can be of any type.</td></tr>
<tr><td width="15%"><var>TARGET</var></td><td width="70%">(Optional) <var>TARGET</var> shall be a pointer or
a target.  It must have the same type, kind type parameter, and
array rank as <var>POINTER</var>.</td></tr>
</table>
<p>The association status of neither <var>POINTER</var> nor <var>TARGET</var> shall be
undefined.
</p>
</dd>
<dt><em>Return value</em>:</dt>
<dd><p><code>ASSOCIATED(POINTER)</code> returns a scalar value of type <code>LOGICAL(4)</code>.
There are several cases:
</p><dl compact="compact">
<dt>(A) When the optional <var>TARGET</var> is not present then</dt>
<dd><p><code>ASSOCIATED(POINTER)</code> is true if <var>POINTER</var> is associated with a target; otherwise, it returns false.
</p></dd>
<dt>(B) If <var>TARGET</var> is present and a scalar target, the result is true if</dt>
<dd><p><var>TARGET</var> is not a zero-sized storage sequence and the target associated with <var>POINTER</var> occupies the same storage units.  If <var>POINTER</var> is
disassociated, the result is false.
</p></dd>
<dt>(C) If <var>TARGET</var> is present and an array target, the result is true if</dt>
<dd><p><var>TARGET</var> and <var>POINTER</var> have the same shape, are not zero-sized arrays,
are arrays whose elements are not zero-sized storage sequences, and
<var>TARGET</var> and <var>POINTER</var> occupy the same storage units in array element
order.
As in case(B), the result is false, if <var>POINTER</var> is disassociated.
</p></dd>
<dt>(D) If <var>TARGET</var> is present and an scalar pointer, the result is true</dt>
<dd><p>if <var>TARGET</var> is associated with <var>POINTER</var>, the target associated with
<var>TARGET</var> are not zero-sized storage sequences and occupy the same storage
units.
The result is false, if either <var>TARGET</var> or <var>POINTER</var> is disassociated.
</p></dd>
<dt>(E) If <var>TARGET</var> is present and an array pointer, the result is true if</dt>
<dd><p>target associated with <var>POINTER</var> and the target associated with <var>TARGET</var>
have the same shape, are not zero-sized arrays, are arrays whose elements are
not zero-sized storage sequences, and <var>TARGET</var> and <var>POINTER</var> occupy
the same storage units in array element order.
The result is false, if either <var>TARGET</var> or <var>POINTER</var> is disassociated.
</p></dd>
</dl>

</dd>
<dt><em>Example</em>:</dt>
<dd><div class="smallexample">
<pre class="smallexample">program test_associated
   implicit none
   real, target  :: tgt(2) = (/1., 2./)
   real, pointer :: ptr(:)
   ptr =&gt; tgt
   if (associated(ptr)     .eqv. .false.) call abort
   if (associated(ptr,tgt) .eqv. .false.) call abort
end program test_associated
</pre></div>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="NULL.html#NULL">NULL</a>
</p></dd>
</dl>


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