"must not match nothing"
I understand that at some level, but my brain is yelling "double negative!!". It might be better to say:
(?!) is the negative look-ahead assertion for the null string. Since the null string matches anything and everything (including nothing), (?!) always fails.
[I was tempted to find a symbolic representation for the null string, but I thougt that would only confuse the issue.]

-QM
--
Quantum Mechanics: The dreams stuff is made of

In reply to Re^5: regex at word boundary by QM
in thread regex at word boundary by mikeraz

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