Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
With PCRE, how can you construct an expression that will only match if a string is not found.
If I were using grep (which I’m not) I would want the -v option.
A more concrete example: I want my regexp to match iff string foo is not in the string. So it would match bar would but not foobar.
Okay, I have refined my regular expression based on the solution you came up with (which erroneously matches strings that start with ‘test’).
This regular expression will match only strings that do not contain foo. The first lookahead will deny strings beginning with ‘foo’, and the second will make sure that foo isn’t found elsewhere in the string.