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Asked: 2026-05-10T15:17:21+00:00

I’m trying to write a regular expression that validates a date. The regex needs

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

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.

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1 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.

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