Regex – What regex can match sequences of the same character


A friend asked me this and I was stumped: Is there a way to craft a regular expression that matches a sequence of the same character? E.g., match on 'aaa', 'bbb', but not 'abc'?


Wouldn't do the trick as it would match 'abc'.


Wouldn't do the trick as it wouldn't match 'bbb', 'ccc', etc.

Best Solution

Sure thing! Grouping and references are your friends:


Will match 2 or more occurences of the same character. For word constituent characters only, use \w instead of ., i.e.: