Regex c# shouldnt match Boolean Operators

Question

Hi,

I'm trying to write a regex which should be able to identify boolean expressions.

I need to avoid cases like IF(AND AND AND). The name of the variable shouldn't be one of the following operators (OR;AND;XOR).

I tried to use [^(OR)] but this wasn't helpful. My Regex looks like this:

(?:<Name> [A-Za-z0-9])

Is there any chance to write a Regex which could find a string like OR and then don't match it?

Thanks for your help.

Orri

Answer 1

Try a negative lookahead:

(?<Name>\b(?!(?:and|x?or)\b)[A-Za-z0-9]+)

This assumes you're trying to match a single literal, like "IF(this AND this)". The regex checks before taking letters, if all it sees is "and" "or" or "xor", it fails.

Also, make sure you have the right RegexOptions set - you probably want IgnoreCase on, and unless you have IgnorePatternWhitespace the space in your original pattern might fail a match, there is no space in if(var1, for example.

Answer 2

Hi, thx u Kobi, i tried your solution and it works fine. Is there any other ways to do stuff like this may one for dummies. I want to write readable code