Get the last day of a month or the number of days in a month

//Get the last day of a month or the number of days in a month
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;
}