Bubble sort in PHP

gistfile1.txt

<?php
$arr = array( 5, 3, 2, 8, 4, 1 );
$arr_len = count( $arr );
$swap = TRUE;
while( $swap ) {
    $swap = FALSE;
    for( $i = 0; $i < $arr_len - 1; $i++ ) {
        if( $arr[$i] > $arr[$i + 1] ) {
            $tmp = $arr[$i];
            $arr[$i] = $arr[$i + 1];
            $arr[$i + 1] = $tmp;
            $swap = TRUE;
        }
    }
}