array_walk()¶
array_walk() is a PHP native function that applies a closure to every element of an array.
array_walk() use the first argument as the array or object with the elements, the second argument as the callback, and the following subsequent arguments as one argument of that closure each. Any missing value in an array is assigned as null, while a missing argument is a fatal error.
The callback may take two arguments. This way, it may apply modifications that take the key into account. This is unlike array_map().
If the walk has to be reflected in the source array, the first argument of the callback must be a reference, and it should be updated.
Although both methods are very similar, array_walk() and array_map() do no have the same argument order, return value nor behavior.
<?php
function square(&$x, $c) { $x = $x * $x + $c; }
$array = [1,2,3];
array_walk($array, square(...));
print_r($array);
// [1, 5, 11];
?>
See also Taming PHP’s array_walk() Function: A Detailed Guide.
Related : array_map()
