From: nobu.nokada@...
Date: 2002-05-08T00:26:13+09:00
Subject: Re: RegExp zero-width negative lookahead

Hi,

At Tue, 7 May 2002 23:33:50 +0900,
Lars Christensen wrote:
> I'm puzzled why this doesn't work the way I expect it to.
> 
> "xxoxxxoxx" =~ /(?!x)ox+o(?!x)/      #=> nil (ok)
> "xx oxxxoxx" =~ /(?!x)ox+o(?!x)/     #=> nil (ok)
> "xx oxxxo xx" =~ /(?!x)ox+o(?!x)/    #=> 3 (ok)
> "xxoxxxo xx" =~ /(?!x)ox+o(?!x)/     #=> 2 (huh!?)
> 
> Why is the string matched in the last case?

Already pointed out the reason, however you really want look
behind?

"xxoxxxo xx" =~ /(?<!x)ox+o(?!x)/      #=> nil (with Oniguruma)

-- 
Nobu Nakada