Get number days of monh

function daysOfMonth($month, $year) {
    $arr = array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
    if ($year % 400 == 0) $arr[1] = 29;
    elseif ($year % 4 == 0 && $year % 400 != 0) $arr[1] = 28;
    elseif ($year % 4 == 0) $arr[1] = 29;
    return $arr[$month-1];
}