function cal_hours_in_month($year, $month) {
    $first = mktime(0, 0, 0, $month, 1, $year);
    $last = mktime(23, 59, 00, $month+1, 0, $year);

    return ($last - $first) / 3600;
}

function cal_hours_in_month($calendar,$month,$year ) {
    return cal_days_in_month($calendar ,$month ,$year) * 24;
}