Keep Duplicates while Using array_diff

Question

I am using array_diff() to take values out of array1 which are found in array2. The issue is it removes all occurrences from array1, as the PHP documentations makes note of.

Answer 1

Write some function that removes elements from first array one by one, something like:

function array_diff_once($array1, $array2) {
    foreach($array2 as $a) {
        $pos = array_search($a, $array1);
        if($pos !== false) {
            unset($array1[$pos]);
        }
    }

    return $array1;
}

$a = array('a', 'b', 'a', 'c', 'a', 'b');
$b = array('a', 'b', 'c');

print_r( array_diff_once($a, $b) );