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Re: List-to-Range generation

by chipmunk (Parson)
on Jun 12, 2001 at 02:55 UTC ( #87672=note: print w/ replies, xml ) Need Help??

in reply to List-to-Range generation

Woops, it also converts (11,2,3) to "11-3" and (1,2,30) to "1-30". :)

Here's one way to fix it:

sub num2range { local $_ = join ',' => @_; s/(?<!\d)(\d+)(?:,((??{$++1}))(?!\d))+/$1-$+/g; return $_; }
The negative look-behind at the beginning and the negative look-ahead near the end prevent the regex from matching only part of a number, like the second 1 in 11 or the 3 in 30.

Replies are listed 'Best First'.
Re: Re: List-to-Range generation
by japhy (Canon) on Jun 12, 2001 at 04:06 UTC
    D'oh. Thanks. Believe it or not, I use that look-behind and look-ahead method in another regex, to find a number in a string less than a given number.

    japhy -- Perl and Regex Hacker

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