- var_dump: documentation ( source)
- array_intersect_key: documentation ( source)
- array_flip: documentation ( source)
- array_filter: documentation ( source)
- array_keys: documentation ( source)
<?php
$a = array(
0 => "apple",
"b" => "banana",
3 => "cow",
"wrench" => "duck"
);
$b = array_intersect_key($a, array_flip(array_filter(array_keys($a), 'is_string')));
var_dump($b);