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How to Regular Expression match not having a constant at the end of a string (.net validator)

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+4 A:

(?> … ) is the syntax for an atomic grouping. And the syntax for look-ahead assertion is just (?! … ).

Edit Try this regular expression instead:

.*$(?<!-CONST)

The .*$ will consume everything and the look-behind assertion will exclude those that end with a -CONST.

Edit Just for completeness’ sake: If your regular expression language does not allow look-behinds, you can also use this one using a look-ahead assertion:

^(.{0,5}|.*(?!-CONST).{5})$

Or using just alternations:

^(.{0,5}|.*([^-].{5}|-([^C].{4}|C([^O].{3}|O([^N].{2}|N([^S].|S[^T]))))))$

Gumbo 2009-11-20 20:08:49

both ValidationExpression=".+(?!-CONST)$" and ValidationExpression="(?!-CONST)$" did not work.

Hogan 2009-11-20 21:06:58

@Hogan: You will need a look-behind assertion since there is nothing after the end of the string.

Gumbo 2009-11-20 21:16:27

Ah, I think the last one will work Gumbo -- The long list of [^x] almost worked, but not on strings smaller than 5 characters... using the | (ors) to make that work should be good. I will try it on Monday. Thanks! I've not had any luck with the (? style operators, I think they are borked in IE's JavaScript.

Hogan 2009-11-20 22:58:10

@Hogan: The first alternation branch `.{0,5}` takes care of strings with up to five characters.

Gumbo 2009-11-20 23:20:47

Just tested -- ^(.{0,5}|.*(?!-CONST).{5})$ worked - thanks Gumbo.

Hogan 2009-11-23 17:43:51

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How to Regular Expression match not having a constant at the end of a string (.net validator)

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