获取下个月的月份

//获取下个月的月份  
public function getNextMonthDays($date){
	$timestamp=strtotime($date);  
	$arr=getdate($timestamp);  
	if($arr['mon'] == 12){  
		$year=$arr['year'] +1;  
		$month=$arr['mon'] -11; 
		$firstday=$year.'-0'.$month.'-01';  
		$lastday=date('Y-m',strtotime("$firstday +1 month -1 day"));  
	}else{  
		$firstday=date('Y-m',strtotime(date('Y',$timestamp).'-'.(date('m',$timestamp)+1).'-01'));  
		$lastday=date('Y-m',strtotime("$firstday +1 month -1 day"));
	}  
	return $lastday;  
}