I've been a Perl programmer since about 1997 and I know a lot about regexes. Not a guru perhaps, but at least a master :) But this I don't get.

I had a string like XT3USI , and I want to test to see if it began with (any char), followed by T, followed by 2 or S. So I used /^.T2|S/

which looked perfect. Reading from L to R, "begins with a char, then a T, then a (2 or an S)". But instead it acted like I had used: /^.T(2|.*S)/

2|S, in my mind, should have alternated chars 2 or S, not 2 or (0-many other chars) followed by S.

I replaced it with /^.(T2|TS)/ which bugs me. But works..

Advice is, as always, appreciated. I use it all the time, but maybe all these years I misunderstood alternation.

In reply to Perl alternation regex looks ok to me? by misterperl

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