The notation is another kind of special parenthesis, starting with (? as in this example: (? \d+)bar This kind of parenthesis "locks up "the part of the pattern it contains once it has matched, and a failure further intoThe notation is another kind of special parenthesis, starting with (? as in this example: (? \d+)bar This kind of parenthesis "locks up" the part of the pattern it contains once it has matched, and a failure further into the pattern is prevented from backtracking into it.
any "non-word" character