From: dblack@...
Date: 2002-12-19T14:19:50+09:00
Subject: Re: How to include some text and exclude other in one regular expression?

Hi --

On Thu, 19 Dec 2002, Greg Millam wrote:

> On Thu, 19 Dec 2002, Usano wrote:
>
> > I would like to match "file 1 of 2" or "1 of 2", but not "day 1 of 2".
> >
> > I can match "file 1 of 2" with...
> >
> > 	/(file)? *\d+ *of *\d+/
> >
> > I wonder if (in the same regex), I can prevent a match to "day 1 of
> > 2"?  The above expression will match this by just ignoring the word
> > "day".
> >
> > Can this be done?
>
> /^(file)?\s*(\d+)\s*of\s*(\d+)$/
>
> \s is any white space character.
> adding ^ and $ to the beginning and end of the expression make it match
> the entire string. since /1 or 2/ will match "day 1 or 2" "file 1 or 2" or
> "In 2002, 1 or 2 people answered this email"
> /^1 or 2$/ makes it match only "1 or 2", with nothing before or after.

Not quite:

  irb(main):001:0> /^1 or 2$/.match("hi there\n1 or 2\nbye!")
  #<MatchData:0x401f05e0>

^ matches beginning of line and $ matches end of line.  \A
matches beginning of entire string, and \z matches end of string (or
\Z, which is end of string minus terminating newline, if any).


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav