compare array using key and a call back function

 <?php

function key_compare_func($key1, $key2)

{

    if ($key1 != $key2)

        return 1;

    

}

$array1 = array('blue'  => 1, 'red'  => 2, 'green'  => 3, 'purple' => 4);

$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan'   => 8);

print_r(array_diff_ukey($array1, $array2, 'key_compare_func'));

---------------------------------------------------

Array ( [red] => 2 [purple] => 4 )