Array Functions
PHP Manual

array_reduce

(PHP 4 >= 4.0.5, PHP 5)

array_reduceIteratively reduce the array to a single value using a callback function

Description

mixed array_reduce ( array $array , callable $callback [, mixed $initial = NULL ] )

array_reduce() applies iteratively the callback function to the elements of the array, so as to reduce the array to a single value.

Parameters

array

The input array.

callback
mixed callback ( mixed $carry , mixed $item )
carry

Holds the return value of the previous iteration; in the case of the first iteration it instead holds the value of initial.

item

Holds the value of the current iteration.

initial

If the optional initial is available, it will be used at the beginning of the process, or as a final result in case the array is empty.

Return Values

Returns the resulting value.

If the array is empty and initial is not passed, array_reduce() returns NULL.

Changelog

Version Description
5.3.0 Changed initial to allow mixed, previously integer.

Examples

Example #1 array_reduce() example

<?php
function rsum($v$w)
{
    
$v += $w;
    return 
$v;
}

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

$a = array(12345);
$x = array();
$b array_reduce($a"rsum");
$c array_reduce($a"rmul"10);
$d array_reduce($x"rsum""No data to reduce");
?>

This will result in $b containing 15, $c containing 1200 (= 10*1*2*3*4*5), and $d containing No data to reduce.

See Also


Array Functions
PHP Manual