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Re: Regexp Confuzzelemt

by akho (Hermit)
on Apr 27, 2007 at 21:41 UTC ( #612461=note: print w/ replies, xml ) Need Help??


in reply to Regexp Confuzzelemt

Regular expressions are greedy by default. That means (.*[^\?]) first matches the whole input for .*, backtracks one character and matches "c" for [^\?].

You want #(.*?)\? (the '?' makes the .* non-greedy).

#([^?]*) also works, of course. But it also matches "TTT" in "aaaaaaaa#TTT" (note that there is no question mark).


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Re^2: Regexp Confuzzelemt
by ikegami (Pope) on Apr 28, 2007 at 02:37 UTC

    But it also matches "TTT" in "aaaaaaaa#TTT"

    That's a difference you introduced. If you put the \? back in, it won't.
    /#(.*?)\?/
    is equivalent to
    /#([^?]*)\?/

    The latter is safer. It's easy to introduced problems when using non-greedy quantifiers. They're not as resilient. For example, you can safely embed the greedy regexp in a larger regexp, but you can't safely embed the non-greedy regexp in a larger regexp.

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