//获取某个月的最后一天或某个月的天数
function getMonthLastDay ( $month,$year )
{
	switch ( $month )
	{
	case 4 :
	case 6 :
	case 9 :
	case 11 :
		$days = 30;
		break;
	case 2 :
		if ( $year % 4 == 0 )
		{
			if ( $year % 100 == 0 )
			{
				$days = $year % 400 == 0 ? 29 : 28;
			}
			else
			{
				$days = 29;
			}
		}
		else
		{
			$days = 28;
		}
		break;

	default :
		$days = 31;
		break;
	}
	return $days;
}