Flutter - Validate a phone number using Regex

Question

In my Flutter mobile app, I am trying to validate a phone number using regex. Below are the conditions.

1. Phone numbers must contain 10 digits.
2. In case country code us used, it can be 12 digits. (example country codes: +12, 012)
3. No space or no characters allowed between digits

In simple terms, here is are the only "valid" phone numbers

0776233475, +94776233475, 094776233475

Below is what I tried, but it do not work.

String _phoneNumberValidator(String value) {     Pattern pattern =         r'/^\(?(\d{3})\)?[- ]?(\d{3})[- ]?(\d{4})$/';     RegExp regex = new RegExp(pattern);     if (!regex.hasMatch(value))       return 'Enter Valid Phone Number';     else       return null;   } 

How can I solve this?

Answer 1

You could make the first part optional matching either a + or 0 followed by a 9. Then match 10 digits:

^(?:[+0]9)?[0-9]{10}$ 

• ^ Start of string
• (?:[+0]9)? Optionally match a + or 0 followed by 9
• [0-9]{10} Match 10 digits
• $ End of string

Regex demo