Reputation: 3898

Regex: Matching on an exclusive either/or

I want a regex that will match for strings of RACE or RACE_1, but not RACE_2 and RACE_3. I've been on Rubular for a while now trying to figure it out, but can't seem to get all the conditions I need met. Help is appreciated.

Upvotes: 1

Answers (4)

Walls

Reputation: 4010

You can use: (\bRACE(_[1])?\b)

It requires the one copy of RACE, and then 0 -> N occurrences of the _[1]. In the square brackets you can include any number you want. EXAMPLE: (\bRACE(_[12345])?\b) will match up to RACE_5. You can then customize it to even skip numbers if you want [1245] for RACE_1, RACE_2, RACE_4, RACE_5 but not RACE_3.

Upvotes: 2

zanegray

Reputation: 768

/RACE(?!_)|RACE_1/

Its a bit of a hack but might fit your needs

EDIT: Here might be a more specific one that works better /RACE(?!_\d)|RACE_1/

In both cases, you use negative lookahead to enforce that RACE cannot be followed by _ and a number, but then specifically allow it with the or statement following.

Also, if you plan on only searching for instances of said matches that are whole words, prepend/append with \b to designate word boundaries.

/\bRACE(?!_\d)|RACE_1\b/

Upvotes: 1