- var_dump: documentation ( source)
- array_merge_recursive: documentation ( source)
<?php
$a = array('a' => 'a', 'b' => 'b', 'z' => array('c' => 'c', 'd' => 'd'));
$b = array('a' => 'c', 'z' => array('c' => 'e'));
var_dump(array_merge_recursive($a, $b));