Php/docs/function.array-reduce

• PHP Manual
• Array Functions
• Iteratively reduce the array to a single value using a callback function

array_reduce

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

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

Description

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

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

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

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.

Examples

Example #1 array_reduce() example

<?phpfunction 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($a, "product", 10)); // int(1200), because: 10*1*2*3*4*5var_dump(array_reduce($x, "sum", "No data to reduce")); // string(17) "No data to reduce"?>

See Also

• array_filter() - Filters elements of an array using a callback function
• array_map() - Applies the callback to the elements of the given arrays
• array_unique() - Removes duplicate values from an array
• array_count_values() - Counts all the values of an array