in reply to regex match triggers "Use of unititialized value ..." warning

$1 and $2 are both defined when the match occurs.

That can't be as there is only one set of capturing parens. The second set of parens are a non-capturing lookahead.

This would probably do what you are trying to achieve: 

s/(?<=\d),(?=\d)/|/g;

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Re^2: regex match triggers "Use of unititialized value ..." warning
by mikeraz (Friar) on Feb 22, 2011 at 13:00 UTC

    Hey future readers,
    If your Perl history has not involved look-ahead and look-behind regexes, this Q&A, especially BrowserUk's A, make for a nice learning opportunity.

    Well, nice if you consider my mis-use something that can be learned from.


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