- var_dump: documentation ( source)
- array_intersect_key: documentation ( source)
- array_keys: documentation ( source)
<?php
$foo = ['foo' => 'bar', 'bar', 'red'];
$bar = ['foo' => 'foo', 'bar' => 'bar', 'green' => 'green'];
var_dump(array_intersect_key($foo, $bar));
var_dump(array_keys($foo));