this post was submitted on 31 Oct 2024
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^.?$|^(..+?)\1+$

Matches strings of any character repeated a non-prime number of times

https://www.youtube.com/watch?v=5vbk0TwkokM

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[–] S_H_K@lemmy.dbzer0.com 4 points 6 days ago (1 children)

No cookie for me I just tried it in Notepad++ and VS code and it matches lines of one characer (first group I think) or the starting of a line that is an at least 2 characters string repeated twice (second group it seems)
so the second group matches abab
abcabc abcdeabce abcdefabcdef

Nothing about prime numbers really only first repetition gets a match. Very interesting Honestly I used regex from years and never had to retort to something like this ever. I can only imagine it useful to check for a password complexity to not be repeated strings like I do for sites that I just want in and use a yopmail.com mail to register a fake user.

[–] NateNate60@lemmy.world 1 points 6 days ago (1 children)

"at least 2 characters repeated [at least] twice" implies the string's length is divisible by a number greater than 1.

[–] S_H_K@lemmy.dbzer0.com 1 points 5 days ago

Yes but the match goes for the first repetition the rest of the string isn't matched no matter the length, again don't find anything about prime numbers unless I checked something wrong. There is another guy who got it right it seems.