date and time operation

Hello everybody ! Does anybody here deal with date and time operation in php ? If you don't mind, please show me they way to do this. I have some date and time functions in ASP and now I have to convert it to PHP. Here are some functions in ASP yr = year(date()) mon = month(date()) currentmonth = cdate(yr & "-" & mon & "- 1") start_week = weekday(currentmonth) nextmonth = cdate(yr & "-" & nextmon & "- 1") first_start_week = dateadd("d", 7, currentmonth) ff_end_week = dateadd("d", -1, first_start_week) diffaweek = datediff("w", first_start_week, nextmonth) day(currentmonth) day(ff_end_week) Do you have any date and time class written in PHP, please share with me Thanks you very much for your attention Thien