From: Rick DeNatale <rick.denatale@...>
Date: 2007-05-05T03:50:03+09:00
Subject: Re: Regular expression - first two alphabets of a string

On 5/4/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> On 03.05.2007 20:30, Rick DeNatale wrote:

> >
> > Or use a negative lookahead:
> > irb(main):001:0> re = /^(?!aa)/
> > => /^(?!aa)/
> > irb(main):002:0> "aa xyz".match(re)
> > => nil
> > irb(main):003:0> "axyz".match(re)
> > => #<MatchData:0xb7baf3e4>
> > irb(main):004:0> "a yz".match(re)
> > => #<MatchData:0xb7bacb1c>
>
> What exactly do you gain by using lookahead instead of a normal match?

The OP was asking for an RE which matched anything which DIDN'T start with aa.

The proposal using if else got it backwards.

Of course you could also just negate the results of the match and use

!str.match(/aa/)

If you just wanted a test.



-- 
Rick DeNatale

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