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  <refentry id="function.array-intersect-ukey">
   <refnamediv>
    <refname>array_intersect_ukey</refname>
    <refpurpose>Computes the intersection of arrays using a callback function on the keys for comparison</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
     <methodsynopsis>
      <type>array</type><methodname>array_intersect_ukey</methodname>
      <methodparam><type>array</type><parameter>array1</parameter></methodparam>
      <methodparam><type>array</type><parameter>array2</parameter></methodparam>
      <methodparam choice="opt"><type>array</type><parameter>...</parameter></methodparam>
      <methodparam><type>callback</type><parameter>key_compare_func</parameter></methodparam>
     </methodsynopsis>
    <para>
     <function>array_intersect_ukey</function> returns an array
     containing all the values of <parameter>array1</parameter>
     which have matching keys that are present in all the arguments.
    </para>
    <para>
     This comparison is done by a user supplied callback function.
     It must return an integer less than, equal to, or greater than zero if the
     first key is considered to be respectively less than, equal to, or
     greater than the second.
    </para>
    <para>
     <example>
      <title><function>array_intersect_ukey</function> example</title>
      <programlisting role="php">
<![CDATA[
<?php
function key_compare_func($key1, $key2)
{
    if ($key1 == $key2)
        return 0;
    else if ($key1 > $key2)
        return 1;
    else
        return -1;
}

$array1 = array('blue'  => 1, 'red'  => 2, 'green'  => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan'   => 8);

var_dump(array_intersect_ukey($array1, $array2, 'key_compare_func'));
?>
]]>
      </programlisting>
      &example.outputs;
      <screen>
<![CDATA[
array(2) {
  ["blue"]=>
  int(1)
  ["green"]=>
  int(3)
})
]]>
      </screen>
     </example>
    </para>
    <para>
     In our example you see that only the keys <literal>'blue'</literal>
     and <literal>'green'</literal> are present in both arrays and thus
     returned. Also notice that the values for the keys
     <literal>'blue'</literal> and <literal>'green'</literal> differ between
     the two arrays. A match still occurs because only the keys are checked.
     The values returned are those of <parameter>array1</parameter>.
    </para>
    <para>
     See also <function>array_diff</function>,
     <function>array_udiff</function>
     <function>array_diff_assoc</function>,
     <function>array_diff_uassoc</function>,
     <function>array_udiff_assoc</function>,
     <function>array_udiff_uassoc</function>,
     <function>array_diff_key</function>,
     <function>array_diff_ukey</function>,
     <function>array_intersect</function>,
     <function>array_intersect_assoc</function>,
     <function>array_intersect_uassoc</function> and
     <function>array_intersect_key</function>.
    </para>
   </refsect1>
  </refentry>

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