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Re: re_search does not find match
From: |
Stepan Kasal |
Subject: |
Re: re_search does not find match |
Date: |
Sun, 23 Feb 2003 09:16:05 +0100 |
User-agent: |
Mutt/1.2.5.1i |
Hello,
I've looked at the following bug-report:
On Tue, Feb 04, 2003 at 01:11:05AM -0500, Patrick Smith wrote:
> char ptrn[] =
> "^(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?).?\\9\\8\\7\\6\\5\\4\\3\\2\\1$";
> char stack[] = "civic";
when experimenting with shortened versions of the pattern, I came to a
conclusion that the regex (current CVS version) works correctly but is
extremely slow. I wasn't patient enough to wait for the result.
The pattern
^(.?)(.?)(.?)(.?)(.?)(.?)(.?).?\7\6\5\4\3\2\1$
works, but is somewhat slow.
Similarilly
^(.)(.?)(.?)(.?)(.?)(.?)(.?)(.?).?\8\7\6\5\4\3\2\1$
works, even though takes some time.
Finally, pattern
^(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.).?\9\8\7\6\5\4\3\2\1$
is really quick.
Is there any reason why the original patters is so evil?
Regards,
Stepan Kasal