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Regular expression for a date. This is for ASP .NET regular expression validator

Posted on 2009-04-28
Medium Priority
Last Modified: 2012-05-06
I need a regular expression for a date. The date can be in one of the three formats
Where the user must enter four digits for the year. "mm" and "dd" are numeric and are mandatory.

mm dd yyyy
Question by:brgdotnet
  • 2
LVL 40

Accepted Solution

mrjoltcola earned 1040 total points
ID: 24256994
You can try it in one fell swoop if you want the capturing groups to always be $1, $2, and $3:

^([01]\d)[-\/ ]([0-3]\d)[-\/ ](\d{4})$

The only thing is this regex will allow different separator characters to be mixed in one date.


To check that, you could break it out into individual regexes or you can capture the separators. If you aren't worried about capturing, then put alternations:

^(([01]\d)-([0-3]\d)-(\d{4})|([01]\d)\/([0-3]\d)\/(\d{4})|([01]\d) ([0-3]\d) (\d{4}))$

In this case, $1 will capture the whole date, but mm, dd and yyyy may be captured in any 3 of the 9 alternate groups.

This regex will filter out a few invalid dates, like months that start with something other than 0 or 1 in the 1st digit, and so forth, but it is not a full date checker.
LVL 40

Expert Comment

ID: 24257016
Or if you really don't care about checking valid digit ranges or capturing, then you can simplify to use \d for all digits and remove parens.

^\d\d[-\/ ]\d\d[-\/ ]\d\d\d\d$


^(\d\d-\d\d-\d\d\d\d|\d\d\/\d\d\/\d\d\d\d|\d\d \d\d \d\d\d\d)$

Assisted Solution

RobbP earned 160 total points
ID: 24258308
Check out this site - for all futures Regex's as its got it all. Much easier than having to fight for expressions. Cheers


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