php date() and mktime() example

This can be more reliable than simply adding or subtracting the number of seconds in a day or month to a timestamp because of daylight saving time.

 <?php  
 $tomorrow = mktime(0, 0, 0, date("m") , date("d")+1, date("Y"));  
 $lastmonth = mktime(0, 0, 0, date("m")-1, date("d"),  date("Y"));  
 $nextyear = mktime(0, 0, 0, date("m"),  date("d"),  date("Y")+1);  
 ?>