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Subject: Regular expression for years after a given one
From: Jose Alves de Castro <jcastro@telbit.pt>
To: fwp@perl.org
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Date: 01 Jun 2004 10:52:55 +0100
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Yesterday, a friend of mine was toying around with some Perl code, when
he got to a function which would only accept a regular expression. He
said:

"How can I say that I want every single year after the one I have? It's
impossible..."

To which I replied:

"Nothing is impossible! Especially in Perl! ;-) " (ok, maybe these
weren't my words at the time, but they seem cool now, right? :-) )

So after a couple of minutes, this is what I came up with:


$year = 2004; # I'm stating it directly to improve clarity

$year =~/(\d)(\d)(\d)(\d)/;

($c,$d,$e,$f) = ($4+1,$3+1,$2+1,$1+1);

$regex =
qr/^\d*(?:${1}${2}${3}[$c-9]|${1}$2[$d-9]\d|$1[$e-9]\d{2}|[$f-9]\d{3})$/;


and that does the trick :-)

Thought I should share this with you guys :-) Thoughts are welcome :-)


BTW: This was made so it would work with $year consisting of four
digits... any care to make it generic? :-)


Regards,

jac

-- 
José Alves de Castro <jcastro@telbit.pt>
Telbit - Tecnologias de Informação

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