CODEWITHSUNDEEP
regex
shiv1m
shiv1m

Reputation: 3

RegEx minimum 4 characters with no repetition

Trying to create a regex where a field should contain minimum 4 characters(only alphabets [a-zA-Z]) where

  1. first 4 alphabets should not repeat. eg aaaa,zzzz not acceptable
  2. first 4 characters should not contain space, numbers, special characters
  3. afterwhich anything is fine

I tried following expression but 1 case is failing which is (a123,a@#!): ^(?=.{1,4}$)(([a-zA-Z]){1,4}\2?(?!\2))+[a-zA-Z0-9!@#$&()\-`.+,"]

Upvotes: 0

Views: 67

Answers (1)

The fourth bird
The fourth bird

Reputation: 163517

You might write the pattern as:

^(?!(.)\1{3})[a-zA-Z]{4}.*

Explanantion

  • ^ Start of string
  • (?!(.)\1{3}) Negative lookahead, assert not 4 of the same characters
  • [a-zA-Z]{4} Match 4 chars a-z A-Z
  • .* Match the rest of the line

Regex demo

Upvotes: 1

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