Sort Array without PHP Function

function cmp($a1, $b1)
{
    if ($a1 == $b1)
    {
        return 0;
    }
    return ($a1 < $b1) ? -1 : 1;
}
$a = array('10.00', '5.00', '6.00');
usort($a, "cmp");
print_r($a);