- array_map: documentation ( source)
- var_dump: documentation ( source)
- array_filter: documentation ( source)
<?php
var_dump(array_map(function ($a, $b) {return "$b => $a";}, array_filter(['a' => 'b', 1 => 'abc', 'c' => false, 'd' => null, 'e' => 0, 'f' => 'z'])));