Write a PHP script to get an array containing all the entries of an array which have the keys that are present in another array

<?php
$first_array = array('c1' => 'Red', 'c2' => 'Green', 'c3' => 'White', 'c4' => 'Black'); 
$second_array = array('c2', 'c4'); 
print_r(array_intersect_key($first_array, array_flip($second_array)));
?>

Sample Output:

Array                                                       
(                                                           
    [c2] => Green                                           
    [c4] => Black                                           
)