If you're interested in the details of differences between the various engines for regular expressions, I really recommend Jeffrey Friedl's Mastering Regular Expressions. That other website also has other stuff I see and is not only centered about the book. I guess that on the Tools, Utilities and Programming Languages page there is a comparison somewhere.

Update: I fell for a slight variation in the URL - http://regex.info/, Jeffrey Friedl's site is about the book which I recommend, while http://regexp.info is some more generic regular expression site.

In reply to Re: Slightly Off Topic: Differences with Regular Expressions in other languages by Corion
in thread Slightly Off Topic: Differences with Regular Expressions in other languages by Cap'n Steve

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