array ( 0 => 'index.php', 1 => 'PHP Manual', ), 'head' => array ( 0 => 'UTF-8', 1 => 'en', ), 'this' => array ( 0 => 'function.array-reduce.php', 1 => 'array_reduce', ), 'up' => array ( 0 => 'ref.array.php', 1 => 'Array Functions', ), 'prev' => array ( 0 => 'function.array-rand.php', 1 => 'array_rand', ), 'next' => array ( 0 => 'function.array-replace-recursive.php', 1 => 'array_replace_recursive', ), 'alternatives' => array ( ), 'source' => array ( 'lang' => 'en', 'path' => 'reference/array/functions/array-reduce.xml', ), ); $setup["toc"] = $TOC; $setup["toc_deprecated"] = $TOC_DEPRECATED; $setup["parents"] = $PARENTS; manual_setup($setup); ?>
(PHP 4 >= 4.0.5, PHP 5, PHP 7, PHP 8)
array_reduce — Iteratively reduce the array to a single value using a callback function
array_reduce() applies iteratively the
callback
function to the elements of the
array
, so as to reduce the array to
a single value.
array
The input array.
callback
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.
Returns the resulting value.
If the array is empty and initial
is not passed,
array_reduce() returns null
.
Version | Description |
---|---|
8.0.0 |
If callback expects a parameter to be passed
by reference, this function will now emit an E_WARNING .
|
Example #1 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"
?>