<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.11 $ -->
<!-- splitted from ./en/functions/array.xml, last change in rev 1.2 -->
<refentry xml:id="function.array-reduce" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>array_reduce</refname>
  <refpurpose>Iteratively reduce the array to a single value using a callback function</refpurpose>
 </refnamediv>
 <refsect1>
  <title>Description</title>
  <methodsynopsis>
   <type>mixed</type><methodname>array_reduce</methodname>
   <methodparam><type>array</type><parameter>input</parameter></methodparam>
   <methodparam><type>callback</type><parameter>function</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>initial</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>array_reduce</function> applies iteratively the
   <parameter>function</parameter> function to the elements of the
   array <parameter>input</parameter>, so as to reduce the array to
   a single value. If the optional <parameter>initial</parameter> is
   available, it will be used at the beginning of the process, or as
   a final result in case the array is empty.
   If the array is empty and <parameter>initial</parameter> is not passed,
   <function>array_reduce</function> returns &null;.
  </para>
  <para>
   <example>
    <title><function>array_reduce</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
function rsum($v, $w)
{
    $v += $w;
    return $v;
}

function rmul($v, $w)
{
    $v *= $w;
    return $v;
}

$a = array(1, 2, 3, 4, 5);
$x = array();
$b = array_reduce($a, "rsum");
$c = array_reduce($a, "rmul", 10);
$d = array_reduce($x, "rsum", 1);
?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   This will result in <varname>$b</varname> containing
   <literal>15</literal>, <varname>$c</varname> containing
   <literal>1200</literal> (= 10*1*2*3*4*5), and
   <varname>$d</varname> containing <literal>1</literal>.
  </para>
  <para>
   See also <function>array_filter</function>,
   <function>array_map</function>,
   <function>array_unique</function>, and
   <function>array_count_values</function>.
  </para>
 </refsect1>
</refentry>

<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"../../../../manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->