Date Validation, Kinda'

Howdy, Has anyone written any date validation function or sequence. I have looked around, but haven't found anything. I am cobbling togather something, but was hoping to not have to re-invent the wheel. The date is formatted YYYYMMDD and is input by the user; $userCentury = substr($userDate, 0, 2); //must be 20 (no problem) $userYear = substr($userDate, 2, 2); //must be 03 or better $userMonth = substr($userDate, 4, 2); // 01-12 $userDay = substr($userDate, 6, 2); // 01-31 It doesn't matter if the month is 02 and they have entered 31 as the day. If any one of the four conditions is not true it gives them a warning. Anyone done this before? Thanks! Jay