How to exclude a string in the middle of a RegEx string?

regex regex-negation regex-lookarounds negative-lookahead negative-lookbehind
automatix picture automatix · May 5, 2016 · Viewed 8.4k times · Source

I have a lot of PHP class files, that contain methods like findFoo(). I want to find (with the RegEx search of my IDE or with grep) all these occurences, in order to replace them by find(). A proper RegEx for that would be find[a-zA-Z0-9]+\(. But there are some methods (e.g. findBarByBuz()) I'd like to exclude from my search. It's the with "By" or "With" in the name.

How to build a RegEx, that matches strings like "find" + "stringWithoutByAndWithoutWith" + "("?

Answer

anubhava picture anubhava · May 5, 2016

You can use negative lookahead: 

/find(?!\w*(?:by|with))\w+\(/i

RegEx Demo

(?!\w*(?:by|with)) is negative lookahead to fail the match when by or with is found after 0 or more word character. \w is equivalent to [a-zA-Z0-9_].

/i is for case insensitive matching.

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