array-walk-recursive.xml

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<refentry xml:id="function.array-walk-recursive" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>array_walk_recursive</refname>
  <refpurpose>Apply a user function recursively to every member of an array</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>true</type><methodname>array_walk_recursive</methodname>
   <methodparam><type class="union"><type>array</type><type>object</type></type><parameter role="reference">array</parameter></methodparam>
   <methodparam><type>callable</type><parameter>callback</parameter></methodparam>
   <methodparam choice="opt"><type>mixed</type><parameter>arg</parameter><initializer>&null;</initializer></methodparam>
  </methodsynopsis>
  <para>
   Applies the user-defined <parameter>callback</parameter> function to each
   element of the <parameter>array</parameter>. This function will recurse
   into deeper arrays.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>array</parameter></term>
     <listitem>
      <para>
       The input array.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>callback</parameter></term>
     <listitem>
      <para>
       Typically, <parameter>callback</parameter> takes on two parameters.
       The <parameter>array</parameter> parameter's value being the first, and
       the key/index second.
      </para>
      <note>
       <para>
        If <parameter>callback</parameter> needs to be working with the
        actual values of the array, specify the first parameter of
        <parameter>callback</parameter> as a
        <link linkend="language.references">reference</link>. Then,
        any changes made to those elements will be made in the
        original array itself.
       </para>
      </note>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>arg</parameter></term>
     <listitem>
      <para>
       If the optional <parameter>arg</parameter> parameter is supplied,
       it will be passed as the third parameter to the
       <parameter>callback</parameter>.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>


 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.true.always;
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      &return.type.true;
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>array_walk_recursive</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$sweet = array('a' => 'apple', 'b' => 'banana');
$fruits = array('sweet' => $sweet, 'sour' => 'lemon');

function test_print($item, $key)
{
    echo "$key holds $item\n";
}

array_walk_recursive($fruits, 'test_print');
?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
a holds apple
b holds banana
sour holds lemon
]]>
    </screen>
    <para>
     You may notice that the key '<literal>sweet</literal>' is never displayed. Any key that holds an
     <type>array</type> will not be passed to the function.
    </para>
   </example>
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>array_walk</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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