RegEx Questions 1

[ietprofessional]

Hi Everyone,

I couldn't find a regex forum so I'm trusting my fellow asp.net-er will have this type of knowledge.

I'm trying to validate a date field before I put it into a database. Does anyone have a regex for dates formatted in all of these ways 3/3/2005, 03/3/2005, 3/03/2005 and 03/03/2005.

Thanks!!!!!

 

[cappmgr]

I know I did not make this one. Probably from

http://regexlib.com/

validationexpression="((^(10|12|0?[13578])([/])(3[01]|[12][0-9]|0?[1-9])([/])((1[8-9]\d{2})|([2-9]\d{3}))$)|(^(11|0?[469])([/])(30|[12][0-9]|0?[1-9])([/])((1[8-9]\d{2})|([2-9]\d{3}))$)|(^(0?2)([/])(2[0-8]|1[0-9]|0?[1-9])([/])((1[8-9]\d{2})|([2-9]\d{3}))$)|(^(0?2)([/])(29)([/])([2468][048]00)$)|(^(0?2)([/])(29)([/])([3579][26]00)$)|(^(0?2)([/])(29)([/])([1][89][0][48])$)|(^(0?2)([/])(29)([/])([2-9][0-9][0][48])$)|(^(0?2)([/])(29)([/])([1][89][2468][048])$)|(^(0?2)([/])(29)([/])([2-9][0-9][2468][048])$)|(^(0?2)([/])(29)([/])([1][89][13579][26])$)|(^(0?2)([/])(29)([/])([2-9][0-9][13579][26])$))"

Marty

 

[ietprofessional]

Are you serious Marty?

 

[cappmgr]

The regex is straight forward, where this person got really sharp is figuring out leap years. I'll break down the first one. If you remember than ^ is the beginning of the string, $ is the end of the string, ? means optional(zero or one), | means OR, and () is a group, [] contain an explicit set of characters to match, {} holds the length(s) and \ is an ecscape character here it is \d which means digit it's easy to follow.
The first one is looking for dates that can have 31 days.

((^(10|12|0?[13578])([/])(3[01]|[12][0-9]|0?[1-9])([/])((1[8-9]\d{2})|([2-9]\d{3}))$)

It's matching the beginning to the end of the string with the ^ and the $
first group (10|12|0?[13578])
10 or 12 or an optional 0 infront of 1,3,5,7,8.
second group ([/]) /
third group (3[01]|[12][0-9]|0?[1-9])
3 followed by a 0 or 1
or
1 or 2 followed by 0,1,2,3,4,5,6,7,8,9
or an optional 0 followed by 1,2,3,4,5,6,7,8,9
fourth group ([/]) /
fifth group ((1[8-9]\d{2})|([2-9]\d{3}))
1 followed by 8 or 9 followed by two digits
or 2,3,4,5,6,7,8,9 followed by three digits.

That's as much as I have ever looked at it, if you ever write some Perl you'll see some regex's that will blow your mind.

Marty