regex - Regular Expression to match valid dates

Question

I'm trying to write a regular expression that validates a date. The regex needs to match the following

• M/D/YYYY
• MM/DD/YYYY
• Single digit months can start with a leading zero (eg: 03/12/2008)
• Single digit days can start with a leading zero (eg: 3/02/2008)
• CANNOT include February 30 or February 31 (eg: 2/31/2008)

So far I have

^(([1-9]|1[012])[-/.]([1-9]|[12][0-9]|3[01])[-/.](19|20)dd)|((1[012]|0[1-9])(3[01]|2d|1d|0[1-9])(19|20)dd)|((1[012]|0[1-9])[-/.](3[01]|2d|1d|0[1-9])[-/.](19|20)dd)$

This matches properly EXCEPT it still includes 2/30/2008 & 2/31/2008.

Does anyone have a better suggestion?

Edit: I found the answer on RegExLib

^((((0[13578])|([13578])|(1[02]))[/](([1-9])|([0-2][0-9])|(3[01])))|(((0[469])|([469])|(11))[/](([1-9])|([0-2][0-9])|(30)))|((2|02)[/](([1-9])|([0-2][0-9]))))[/]d{4}$|^d{4}$

It matches all valid months that follow the MM/DD/YYYY format.

Thanks everyone for the help.

Answer 1

This is not an appropriate use of regular expressions. You'd be better off using

[0-9]{2}/[0-9]{2}/[0-9]{4}

and then checking ranges in a higher-level language.