Method of calculating the date of

I need to calculate the current date, the end of the day a few months back.

For example
today :2013-10-18 日:2014-6-30
I want to calculate the end of eight months after the day4 months after the end of the day :2014-2-28<-! Main posts under Banner (D4) -><-! Posts under the main text (D5) ->
Reply:
http://blog.csdn.net/liwenfeng1022/article/details/6534176
Reply:
First calculate X months after the month in which month of which year is then judged this month is a big month (31) or Satsuki (30), to determine if it is in February this year is a leap year (29)
Reply:
Ah good detail on the first floor, the top one. .