For all the "why" people, here's my guess as to why. A regular expression is just a program. It has a start point, then tries to do somethings, back tracks, and returns true if the regexp holds true for some part of the string, depending on how the regexp is written.

By inverting it, you may get a more optimized regexp. It is easier to solve some problems and get an answer. Sometimes it's faster to say what the answer isn't and go by that.

----
Give me strength for today.. I will not talk it away..
Just for a moment.. It will burn through the clouds.. and shine down on me.

In reply to Re: Regex::Reverse tricky test cases by exussum0
in thread Regex::Reverse tricky test cases by Roy Johnson

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