How to disallow consecutive five digits and more using regex?

Question

I would like to disallow if the string contains consecutive five digits and more like: 12345, 11111, 123456.

I have got success in disallowing any number in string using

Answer 1

The regex matching 5 consecutive digits is \d{5}.

To disallow such a string (actually, even more consecutive digits), at any position in the source string, this regex should be put:

• inside a negative lookup: (?!...),
• after a regex matching any number (zero or more) of any chars .*? (reluctant variant).

After this negative lookup, there should be a regex matching the whole string: .+ (I assume that you are not interested in an empty string, so I put +, not *).

The whole regex above should be preceded with ^ and followed with $ anchors.

So the whole regex can be: ^(?!.*?\d{5}).+$