How to validate a user name with regex?

Question

This seems to match the rules I have defined, but I only starting learning regex tonight, so I am wondering if it is correct.

Rules:

• Usernames can cons

Answer 1

In my opinion, adding a limited scope to this model would be better

[a-zA-Z0-9]+([_ -]?[a-zA-Z0-9]){5,40}$