From: Martin DeMello <martindemello@...>
Date: 2002-12-01T16:42:01+09:00
Subject: Re: Regular expressions from the end of a string

the Bare <grrr@wild.net> wrote:
> Hi:
> 
> Is there anyway to have a regular expression match from the end of a 
> string?  I would like to match something like the following:
> 
> TextThatIWantToMatchThatMayHaveNumbersAndHyphensInIt-0123.EXT
> 
> The hyphen may or may not be there.  For example, from 
> "TK-23-ab-355.bnd" I would want to find "TK-23-ab".
> 
> Because, the text I want to match may have numbers in it, it seems to me 
> that I somehow have to match from the end of the string. I want to I've 
> tried expressions like the following:
> 
> match = /^(.*)[^0-9]*[0-9]+\.(jpg|gif)$/i.match(filename)
> 
> But it didn't work (of course!).  Is there anyway to do what I want 
> without actually reversing the string?

Since you want all the rest of the string, how about 
match = filename.gsub(/-?\d+\.(jpg|gif)$/,'')

Or to match it with a regex, add a (.*?) in front
match = /(.*?)-?\d+\.(jpg|gif)$/.match(filename)
which will capture your string in match[1]

The .*? is a non-greedy match, so it'll match only until the rest of the
regex does. \d is the digit character class (saves writing [0-9]). The
gsub's a lot more efficient, though.

And here's the sexeger page I referred to earlier:
http://japhy.perlmonk.org/sexeger/sexeger.html

martin