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<refentry xml:id="function.array-diff-ukey" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>array_diff_ukey</refname>
  <refpurpose>Computes the difference of arrays using a callback function on the keys for comparison</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>array</type><methodname>array_diff_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>
   Compares the keys from <parameter>array1</parameter> against the keys
   from <parameter>array2</parameter> and returns the difference.
   This function is like <function>array_diff</function> except the
   comparison is done on the keys instead of the values.
  </para>
  <para>
   Unlike <function>array_diff_key</function> an user supplied callback
   function is used for the indices comparision, not internal function.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>

    <varlistentry>
     <term><parameter>array1</parameter></term>
     <listitem>
      <para>
       The array to compare from
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>array2</parameter></term>
     <listitem>
      <para>
       An array to compare against
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>...</parameter></term>
     <listitem>
      <para>
       More arrays to compare against
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>key_compare_func</parameter></term>
     <listitem>
      <para>
       <type>callback</type> function to use.
       The callback function must return an integer less than, equal
       to, or greater than zero if the first argument is considered to
       be respectively less than, equal to, or greater than the second.
      </para>
     </listitem>
    </varlistentry>

   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns an <type>array</type> containing all the entries from
   <parameter>array1</parameter> that are not present in any of the other arrays.
  </para>
 </refsect1>

<!--
 <refsect1 role="errors">
  &reftitle.errors;
  &errors.no.unusual.errors;
 </refsect1>
-->
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>array_diff_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_diff_ukey($array1, $array2, 'key_compare_func'));
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
array(2) {
  ["red"]=>
  int(2)
  ["purple"]=>
  int(4)
}
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    This function only checks one dimension of a n-dimensional
    array. Of course you can check deeper dimensions by using
    <literal>array_diff_ukey($array1[0], $array2[0], 'callback_func');</literal>.
   </para>
  </note>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>array_diff</function></member>
    <member><function>array_udiff</function></member>
    <member><function>array_diff_assoc</function></member>
    <member><function>array_diff_uassoc</function></member>
    <member><function>array_udiff_assoc</function></member>
    <member><function>array_udiff_uassoc</function></member>
    <member><function>array_diff_key</function></member>
    <member><function>array_intersect</function></member>
    <member><function>array_intersect_assoc</function></member>
    <member><function>array_intersect_uassoc</function></member>
    <member><function>array_intersect_key</function></member>
    <member><function>array_intersect_ukey</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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