regex lookbehind search seems not fully functional

[bjornborg]

Everything version: 1.4.1.935 (x64)
I created a file "aaaxxxbbbxxx", and search the file using regex:"(?<=b{3})xxx", it works fine, I can see "aaaxxxbbbxxx" file in result.
But if I use regex "(?<=b*)xxx", there's no result.

[ovg]

AFAIK this regex flavor doesn't support variable length in lookbehind

[void]

Everything uses PCRE.

Each top-level branch of a lookbehind must be of a fixed length.

https://www.pcre.org/current/doc/html/pcre2syntax.html#SEC19

[NotNull]

regex "(?<=b*)xxx"

I don't understand this regex. How is this functionally different from "(?<=b)xxx" ? (without the *).
Where could this be useful?

[bjornborg]

Everything uses PCRE.

Each top-level branch of a lookbehind must be of a fixed length.

https://www.pcre.org/current/doc/html/pcre2syntax.html#SEC19

OK, I see, thanks a lot.

[NotNull]

I don't understand this regex.

I'm a bit slow ... This regex is useful for more complex situations like "(?<=b*c*d*)xxx"