What are the best places to learn regular expression (PHP)?

Question

What are the best places to learn regular expression (PHP)?

Answer 1

http://www.regular-expressions.info and RegExr.

^{RegExr is also available for download.}

Answer 2

The best way is to test things out. I believe playing around with it is the best teacher. Try some of the online regex testers out there:

http://rubular.com is one of the best.

There's a bit of small documentation underneath. However, if you need more you could go to:

http://www.regular-expressions.info

Answer 3

Mastering Regular Expressions, Third Edition -- really good book; this is where I learnt them (for Python). It has practically everything you'll need that's regex related. The first couple of chapters are like tutorials for regexes and then you have a chapter each for regex flavours in some popular languages (PHP?). Overall, I'd say this book rocks!

Answer 4

There are lots of uses for regular expressions, make sure the resources include how to do regular expression replaces and to get multiple groups from the same expressions.

Oh yeah, and: http://stackoverflow.com/questions/tagged/regex

Answer 5

perldoc perlre and perldoc perlrequick

Answer 6

Kodos is a great python based tool for testing regex's. I've used it on Windows with great success. I've used regular-expressions.info more than I care to admit

Answer 7

Another good regex tool is RegexBuddy. It understands several flavors and dialekts of regular expressions and can be used to construct and debug them.