From: dblack@...
Date: 2002-09-08T06:23:30+09:00
Subject: Re: Regular expression question

Hi --

On Sun, 8 Sep 2002, Rich Kilmer wrote:

> As I don't have my copy of Mastering Regular Expressions at home, and
> I'm not that good with them (yet :-) I question for the RegEx gurus:

Answering questions addressed to gurus is usually a guarantee that
I'll get it wrong, but I'll try anyway :-)

> if I want to match "dec" at the beginning of a string how would I do
> that:
>
> /\Adec/
>
> matches on string "decimal" and "dec" basically I want 'dec' not
> followed by [A-Za-z0-9_-] but anything else is ok (including 'dec' being
> the entire string)

You want a negative lookahead:

  /\Adec(?![A-Za-z0-9_-])/

You can shorten it to:

  /\Adec(?![\w-])/

the difference being that \w is locale-dependent (which is quite
likely good, if you want to avoid all alphanumeric characters).


David

-- 
David Alan Black                      | Register for RubyConf 2002!
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