(?!(?:\n\n).) matches the empty string, and doing that many times (*) doesn't make sense.

You probably want (?:(?!\n\n).)* instead.

But it's hard to tell without seeing the expected result.

my $s = do {local $/, <DATA>};

That's pretty useless since you haven't defined any __DATA__ section.

In reply to Re: Negative Look Ahead issue by moritz
in thread Negative Look Ahead issue by prasadbabu

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