Question : Need to allow a hyphens ("-") for user names in text field

I have this for a Regular Expression for a user name text field: [0-9a-zA-Z]{6,20}

However, found out that users wanted to add a hyphen or "-" to user names. How can I adjust my regular expression  [0-9a-zA-Z]{6,20} to allow the hyphens or "-"?

Answer : Need to allow a hyphens ("-") for user names in text field

You would need to escape the hyphen with a backslash within the character set brackets:

   [0-9a-zA-Z\-]{6,20}