in reply to Re: To find, this not preceded by that, use (?<!pattern)(?!pattern) (or not)
in thread To find, this not preceded by that, use negative look-behind with negative look-ahead , use (?<!pattern) with (?!pattern), (?<!pattern)(?!pattern)

Would "foobar" be "\S{3} not preceded by 'bar'"? Is that what you are trying to find?

Yes it would. I thought this much was clear.

I see now the wording of (?!pattern) is what confused me

If you are looking for a "bar" that isn't preceded by a "foo", /(?!foo)bar/ will not do what you want. That's because the (?!foo) is just saying that the next thing cannot be "foo" -- and it's not, it's a "bar", so "foobar" will match. Use look-behind instead (see below).

And I'm certain now, that I only tried s/((?!bar)\S{3,})/\U$1/g ; without \b

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