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Re^2: Strange regex to test for newlines: /.*\z/

by betterworld (Deacon)
on May 21, 2007 at 12:33 UTC ( #616541=note: print w/ replies, xml ) Need Help??


in reply to Re: Strange regex to test for newlines: /.*\z/
in thread Strange regex to test for newlines: /.*\z/

It works because . does not match newlines by default.

That's what I meant by "horizontal characters". But as "." has an asterisk after it, the regex should also match if "." does not match, shouldn't it?


Comment on Re^2: Strange regex to test for newlines: /.*\z/
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Re^3: Strange regex to test for newlines: /.*\z/
by jettero (Monsignor) on May 21, 2007 at 15:27 UTC
    It would work if you used $ instead. \z specifically asks for the end of the string and . won't match the \ns without a /s on the end. So .* and \z aren't adjacent in your first example — without the /s.

    It probably would work with "\n" because .* could match 0 chars. But in your example, it already matched several chars before the \n which it refuses to slurp, so it (meaning the DFA) can't get to the \z at the end.

    Of course, the more I think about it... you might argue that the .* should backtrack, skip over the \n and continue to match the 0 chars right before the \z. I believe \z has a special meaning though. It's not really matching characters. It's more of a border on things, like \b, so I suspect there really aren't 0 characters before it because it's not really there.

    UPDATE: I'm completely convinced this is a bug based on "id-616551" below.

    -Paul

Re^3: Strange regex to test for newlines: /.*\z/
by Joost (Canon) on May 21, 2007 at 12:37 UTC

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