Regex for NANP phone number with non-repeating last 7 digits
问题 I have to validate a 10 digit (US) phone number in the NANP format (no special characters allowed) in .NET and also check to make sure the last 7 digits of the phone number are non-repeating. So far, I have written the following regex to validate the NANP format ^(?:[2-9][0-8][0-9])([2-9][0-9]{2}[0-9]{4})$ How do I modify this regex to also account for non-repeating last 7 digits? Please note that using two regexes is not an option due to constraints of existing code. Edit: I have to check