From: Tony De <tonydema@...>
Date: 2008-03-29T16:16:59+09:00
Subject: Re: Regular Expression help

David A. Black wrote:
> Hi --
> 
> On Sat, 29 Mar 2008, Tony De wrote:
> 
>> count on it being enclosed in paren's.  Although I can expect the right
>> paren to always be there.
>>
>> So here's my regex exp:
>> sourceip = line.scan(/\b(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\b/)
>> And as you might expect, it is pulling both IP addresses.  Is there a
>> way I can adjust the expression to grab the second IP testing for the
>> ")" or is there another method I can use?  Short of dissecting the
>> entire string backwards and testing whether I have a number or a char,
>> decimal and at most 3 chars from it, etc?
> 
> What you want is an IP address, possibly followed by ')' and
> definitely coming at the end of the string (give or take a newline
> character after it). That can be expressed like this:
> 
>    /((\d{1,3}\.){3}\d{1,3})(?=\)?\Z)/
> 
> I've got 3 occurences of (\d{1,3}\.), followed by the same thing
> without a dot. I've stipulated that this submatch be "looking at"
> (i.e., positioned just before) an optional ')' followed by the end of
> the string. (\Z gives you end of string, ignoring a possible terminal
> newline.)
> 
> With your line, it gives you:
> 
> irb(main):039:0> line[re]   # re.match(line)[0], or whatever
> => "222.222.222.22"
> 
> 
> David

David, you rock.  I'll give it a try.  Those expressions make my head 
hurt.  But I've been taking in 
http://www.regular-expressions.info/tutorial.html.  It seems to cover a 
lot of foundation and application.  Thanks again!

tonyd
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