in reply to Re: Look Ahead:
in thread Look Ahead:

I knew how to match the string but I want to know why it is working like that?Explain me?

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Re^3: Look Ahead:
by rmflow (Beadle) on Apr 02, 2010 at 12:42 UTC
    Because sometimes you need to look ahead without actual matching.

    For example: 
    $num = scalar reverse "1000000000000";
$num =~ s/(\d\d\d(?=\d))/\1,/g;
print scalar reverse $num;

    [download]
    will print 1,000,000,000,000
[reply]
[d/l]

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