Buble sort in php

buble_sort.php

function bubble_sort($sortarr) {
    // Bubble sorting
    $array_count = count($sortarr);
    for($x = 0; $x < $array_count; $x++){
        for($a = 0 ;  $a < $array_count - 1 ; $a++){
            if($a < $array_count ){
                if($sortarr[$a] > $sortarr[$a + 1]) swap($sortarr, $a, $a+1);
            }
        }
    }
    return $sortarr;    
}

function swap(&$arr, $a, $b) {
    $tmp = $arr[$a];
    $arr[$a] = $arr[$b];
    $arr[$b] = $tmp;
}