From: Brian Candler <b.candler@...>
Date: 2008-11-27T23:44:33+09:00
Subject: Re: reg exp

Hai anh Le wrote:
> Hi every body. I'm a newbie in Ruby and have problem with reg exp.
> 
> In one string as example "The device 13c include something as in Fig. 2a
> and 3b", I want to detect some numbers have style "13c" and ignore
> others number have style "2a and 3b"
> 
> I use /(\d+[a-z]*)( [^a][^n][^d] )(\d)+[a-z]*/ but it not ok. Can
> someone help me plz?

Tricky. I suggest:

  str.scan(/\d+[a-z]?(?: and \d+[a-z]?)?/).reject { |e| /and/ =~ e }

I thought about lookahead assertions, e.g. (?! and \d+), but since these 
don't consume characters the 3b is likely to be matched later as a 
standalone number.

Details at http://www.ruby-doc.org/docs/ProgrammingRuby/ - click on "The 
Ruby Language" in the contents, and scroll down to Extensions.
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