Regular expression to match string without repeated characters

Question

I'm looking for a simple regular expression to match the string where no repeated characters. Example:

Why do you want this as a regex instead of just coding it out? — bmargulies, Aug 08 '15 at 19:40
I can`t negative regex match. App validator accept only positive matching. — Andrey M, Aug 08 '15 at 19:55
What do you mean by no repeated characters? Did you mean no repeating letters, because `JHMCU26809C211501` repeats `1`? And if yes - then what is wrong with `JHMCU268091111111`? — ndnenkov, Aug 08 '15 at 19:56
None of your outcomes match the stated problem. Why is that? — , Aug 08 '15 at 20:49

score 19 · Accepted Answer · answered Aug 08 '15 at 20:04

19

You may do negation through negative lookahead.

^(?!.*(\w)\1{3,}).+$

answered Aug 08 '15 at 20:04

Avinash Raj

If it is three times or more, it would be ^(?!.*(\w)\1{2,}).+$ – David Welborn Dec 30 '21 at 23:07

score 0 · Answer 2 · answered Aug 08 '15 at 20:54

0

If its a duplicate 3 or more times in a row, this is the fastest
way to do it. (no phony demo provided)

^(?:(.)(?!\1{2}))+$

 ^ 
 (?:
      ( . )                         # (1)
      (?! \1{2} )
 )+
 $

answered Aug 08 '15 at 20:54

2 Answers2