From: Axel Etzold <AEtzold@...>
Date: 2007-05-15T04:46:47+09:00
Subject: Re: Regex problem, probably simple

Dear Jim,

assuming that you have the following in webpage "a0.html":

...
<id=xxx>
...
<a href=??????>
... 

,

you can run the following script:

my_page=IO.readlines("a0.html").to_s
r1=/<id=xxx>/
r2=/(?=<a href=[^>]+>)/
r3=/<a href=([^>]+)>/
text=my_page.split(r1)
text2=text[1..-1].join.split(r2)[1]
ref=r3.match(text2)
p 'the first link was : ' + ref[1]

I read in the entire page into a string my_page,
split that into an Array at the first occurrence of
regexp r1, join it back again into a string,
then split that into an array using regexp r2, which keeps the
delimiter (of form <a href=[^>]+> ...that's what the (?= .. ) syntax is for) , rather than dropping it, as in the first split.
If there is text before the first occurrence of r3, 
you'll find it in the first element of the splitted string:

 text[1..-1].join.split(r2)[0],

and the first occurrence of r3 is in the second element

text2.

If you want more information about Regexps, you'll might
find this helpful:

http://www.regular-expressions.info/ruby.html

Best regards,

Axel 
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