- var_dump: documentation ( source)
- array_replace_recursive: documentation ( source)
<?php
$array1 = ['foo' => ['a' => 1, 'b' => 2], 'bar' => 1];
$array2 = ['foo' => ['c' => 3, 'a' => 4, 'd' => 4], 'bar' => 2];
var_dump(array_replace_recursive($array1, $array2));