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Re: Regex problem - (non)greedy?

by ikegami (Pope)
on Nov 14, 2013 at 14:18 UTC ( #1062589=note: print w/replies, xml ) Need Help??


in reply to Regex problem - (non)greedy?

Why do matches aginst (.*) and (.*?) result in exactly the same result?

Because there's only one ghi.

... /c/ matches "c" (at position 3) /d/ matches "d" /.*/ matches " cd EF ghi jkl" /g/ fails -> backtrack /.*/ matches " cd EF ghi jk" /g/ fails -> backtrack /.*/ matches " cd EF ghi j" /g/ fails -> backtrack ... /.*/ matches " cd EF " /g/ matches "g" /h/ matches "h" /i/ matches "i" -> success
... /c/ matches "c" (at position 3) /d/ matches "d" /.*?/ matches "" /g/ fails -> backtrack /.*?/ matches " " /g/ fails -> backtrack /.*?/ matches " c" /g/ fails -> backtrack ... /.*?/ matches " cd EF " /g/ matches "g" /h/ matches "h" /i/ matches "i" -> success

What needs to be done to get only the "EF" as a result?

(?s:(?!STRING).)* is to STRING as [^CHAR]* is to CHAR.

/cd(?:(?!cd|ghi).)ghi/s

Note: Unlike the trick of adding ^.* to the start of the pattern, this pattern can be used in other patterns.

Note: I think want "EF" instead of " EF ", but it's easier just to trim the whitespaces afterwards.

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[Corion]: marto: Well, I think they go a tour every two years and I think it's hard to even get a connection with the crowd at a 20k people concert... But maybe after this time I'll stop too ;)
[Corion]: I still have to see the Pet Shop Boys live before they stop touring at all
[marto]: yeah, I think that as a group creatively they're done. I can understand how it'd be hard to stop the process, album/tour, album/tour, if that's pretty much all you've ever done :)
[marto]: Corion yes I saw them Pandemonium_Tour
[Corion]: marto: Yeah, and I doubt that they'll ever get back to something like Violator/Songs of Faith and Devotion - it would either alienate their "regular" crowd, or be "too much Violator" ;)
LanX needs to see Freddy Mercury'
[Corion]: marto: Yeah, I have that on DVD even, and I missed them last year because I was in London at the time ironically ;)
[marto]: put me in the mood to listen to this now :)
[Corion]: LanX: Well, grab a shovel :)
[Corion]: Kraftwerk also are still touring (well, only Ralf Hütter and Florian Schneider), but I'm too tight fisted to spend EUR 150+ for standing around two hours ;)

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