Regex to restrict a string for no more than 5 consecutive numeric characters and no more than 8 numeric characters in total

Question

I'm trying to build a regex that restricts a string for no more than 5 consecutive numeric characters and no more than 8 numeric characters in total.

For example :

I was able to create this till now: /^((\d{0,5}[a-zA-Z]+\d{0,5})+|\d{0,5})$/

Many thanks in advance

JvdV · Accepted Answer · 2021-08-23 08:52:19Z

1

A negative lookahead with some alternation might be helpfull here:

^(?!.*\d{6}|(?:.*\d){9})[A-Za-z\d]+$

See an online demo

^ - Start-line anchor.
(?! - Open negative lookahead:
- .*\d{6} - 0+ Chars other than newline followed by 6 digits.
- | - Or:
- (?:.*\d){9} - A non-capture group of 0+ chars other than newline followed by a single digit matched 9 times.
- ) - Close negative lookahead.
[A-Za-z\d]+ - Match 1+ alphanumeric characters.
$ - End-line anchor.

answered Aug 23, 2021 at 8:52

JvdV

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