Given: 

while(<>) {
    s/(\d),(?=\d)/$1|$2/g;
    print;
}

[download]
This triggers a warning of Use of uninitialized value in concatenation (.) or string whenever the regex matches.

Which I don't comprehend:
$_ is defined
$1 and $2 are both defined when the match occurs.
So why does the warning trigger?


Be Appropriate && Follow Your Curiosity

In reply to regex match triggers "Use of unititialized value ..." warning by mikeraz

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