array_reduce

(PHP 4 >= 4.0.5, PHP 5, PHP 7)

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

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 )

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.

Returns:

Returns the resulting value.

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

Changelog:

5.3.0

Changed initial to allow mixed, previously integer.

Examples:

array_reduce() example

<?php
function sum($carry, $item)
{
    $carry += $item;
    return $carry;
}
 
function product($carry, $item)
{
    $carry *= $item;
    return $carry;
}
 
$a = array(1, 2, 3, 4, 5);
$x = array();
 
var_dump(array_reduce($a, "sum")); // int(15)
var_dump(array_reduce($a, "product", 10)); // int(1200), because: 10*1*2*3*4*5
var_dump(array_reduce($x, "sum", "No data to reduce")); // string(17) "No data to reduce"
?>