(.)(?!\1)\1
I think this should match any character [c], followed by any character that is not [c], then followed by [c] again.
like 'aba', 'xyx'
But online regexr validator is telling me im wrong. Where is the issue?
Thanks in advance.
CodePudding user response：
You were correctly checking if the second character isn't the same as the first (group), but you forgot to allow a match on the second character otherwise.
(.)(?!\1).\1
https://regex101.com/r/vvapcB/1
If you want to also want the matches to be 3 characters only,
(?=.{3}$)(.)(?!\1).\1