What's the point of these regex'es?

Question

I'm trying to solve a regex puzzle, and portions of the regexes keep consisting of pieces like this:

([^Xa-ehY]|[^f-zW])

or

([^2]|[^D-Za]|[D-Ze-f])

These confuse me.

Take the first one, for example: [^Xa-ehY]|[^f-zW]). Doesn't this mean "not Xa-ehY OR not f-zW"? And doesn't that equate to "any character"? Take e for example. It wouldn't match the first one, but it would match the second. W would not match the second, but it would match the first.

Same with ([^2]|[^D-Za]|[D-Ze-f]). This means "not 2 OR not D-Ze-f OR D-Ze-f", right? Which again amounts to "any character."

Am I missing something? Is this just a convoluted substitution for a single . regex?

Answer 1

You can throw a bunch of text at them in a regex tester to see if any characters overlap. It's pretty crude, but your first example (\[^Xa-ehY\]|\[^f-zW\]) overlaps on the letter 'h'. The second example does look like it should match anything.

Answer 2

Since it is a puzzle you should look closer.

[^Xa-ehY]|[^f-zW] is not the same as . since they intersect at h (f-z contains h) so it would be the same as [^h]

Answer 3

I think there are some characters that overlap. E.g. in the first on the lowercase h wouldn't match either side.

Admittedly the second one looks like it is just "."