From: Pit Capitain <pit.capitain@...>
Date: 2002-05-20T08:14:55+09:00
Subject: Re: Need Multiline Regexp Help

Hi Jim,

> I am having trouble understanding
> what is happening. Can someone help?
> 
> irb(main):003:0> s="fred\nhello"
> "fred\nhello"
> irb(main):005:0> s.scan(/f.*[^l]/m) 
> ["fred\nhello"]   ## I thought [^l] would not match 'l'

The RE searches for an "f" followed by as many characters
(-> "red\nhell") followed by one character that isn't "l" (-> "o").

> irb(main):006:0> s.scan(/(f.*)[^l]/m)
> [["fred\nhell"]]  ## Again, why the match of 'll'

See above. It returns the sub-expression, which is everything up to 
the last "o".

> irb(main):009:0> s.scan(/(f.*)[^lo]/m)
> [["fred\nh"]]     ## Why adding a second char changes the result?

In this RE, the last character should be something which is neither 
"l" nor "o", so this matches the "e" in hello. The sub-expression in 
parenthesis returns everything up to this last character, which is 
"fred\nh".

If you want to look for an "f" followed by anything but an "l", you�d 
have to specify /f[^l]*/.

Hope that helps.

Regards,
Pit