CODEWITHSUNDEEP
python-3.xregex
user12551055
user12551055

Reputation:

python regex validator for repetitive character

I am struggling to write regex pattern. I want, It must NOT have or more consecutive repeated digits.

5133-3367-8912-3456 
so it should return false, Consecutive digits are repeating 4 or more times


5123-4567-8912-3456
and it should return True

my code now: re.match('[0-9]{4}', string)

I can do with many way in python but i want to do with regex as my case is very different.

Can anyone please help me in this case?

Upvotes: 1

Views: 120

Answers (2)

Lieven Keersmaekers
Lieven Keersmaekers

Reputation: 58431

If you remove all hyphens first, you can use a positive lookahead to search for a repeating pattern for a specified number of times.

if re.search(r"(\d)(?=\1{3})", string):
    # Successful match -> This would be your false case
else:
    # Match attempt failed -> This would be your true case

Upvotes: 0

anubhava
anubhava

Reputation: 784938

You may use this regex in python with a negative lookahead:

^(?![\d-]*(\d)(?:-?\1){3})\d+(?:-\d+)*$

RegEx Demo

RegEx Details:

  • ^: Start
  • (?![\d-]*(\d)(?:-?\1){3}): Negative lookahead to fail the match when we find 4 repeats of the same digit optionally preceded by a single -
  • \d+(?:-\d+)*: Match digits sets delimited by -
  • $: End

Upvotes: 1

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