Calculating Age in Years in PHP

Well calculating age in PHP seems to be not that big thing Date calculation is something wich would be a good topic for Programming for Beginners Lesson 2 It is not that much used cause Databases give a lot of nice date calculating functions like MySQL DateDiff or similar function on other Database. PHP has not had a DateDiff function from home until PHP 5.3, unfortunatelle the PHP Version on server was 5.2.4 so i could not use the PHP DateDiff Function from the new DateTime Functions. Cause i was a bit lazy i thought it might be easy to find a usefull function to calculate Age in PHP but anything i found was a bunch of useless forum discussions and not 100% correct working answers so i wrote an own one. The problem is 365 days is not the correct number of days for a year. Every 4 years there are 366 cause of the leap year But every 100 years there is no leap year. Like 1900 But every 400 years there is. Like 2000 So for every 4 years of age, this method gets wrong one more day. A more correct calculation would be Could still have some combinations were it returns a wrong result, so the first example is still better. Maybe i gonna past a full datediff function later once, otherwise upgrade to PHP 5.3, so as i will do soon.