array-intersect-key.xml

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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.array-intersect-key">
 <refnamediv>
  <refname>array_intersect_key</refname>
  <refpurpose>Computes the intersection of arrays using keys for comparison</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>array</type><methodname>array_intersect_key</methodname>
   <methodparam><type>array</type><parameter>array</parameter></methodparam>
   <methodparam rep="repeat"><type>array</type><parameter>arrays</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>array_intersect_key</function> returns an array
   containing all the entries of <parameter>array</parameter>
   which have keys that are present in all the arguments.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>array</parameter></term>
     <listitem>
      <para>
       The array with master keys to check.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>arrays</parameter></term>
     <listitem>
      <para>
       Arrays to compare keys against.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns an associative array containing all the entries of 
   <parameter>array</parameter> which have keys that are present in all
   arguments.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      &array.changelog.require-only-one;
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>array_intersect_key</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$array1 = array('blue'  => 1, 'red'  => 2, 'green'  => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan'   => 8);

var_dump(array_intersect_key($array1, $array2));
?>
]]>
    </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>array</parameter>.
  </para>
  <para>
   The two keys from the <literal>key =&gt; value</literal> pairs are
   considered equal only if
   <literal>(string) $key1 === (string) $key2 </literal>. In other words
   a strict type check is executed so the string representation must be
   the same.
  </para>
 </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_diff_ukey</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_ukey</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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