array_walk()

array_walk(...$args): bool

Parameters

Name	Type	Description
$a	array	array to walk
$fn	closure	callback fn(value, key) — receives COPIES, not references

true; calls $fn for every element.

$n = 0;
array_walk([10, 20, 30], fn($v, $k) use (&$n) => $n = $n + $v);
echo $n;