Question

In my C# application, I use a regular expression to validate the basic format of a US phone number to make sure that the user isn’t just entering bogus data. Then, I strip out everything except numbers, so this:

[phone] x1234

becomes

12345678901234

in the database. In various parts of my application, however, I would like to convert this normalized phone number back to

[phone] x1234

What’s the best way to do such a thing? (Don’t worry about accounting for international phone number formats, by the way.)

Answer 1

String.Format('{0:(###) ###-#### x ###}', double.Parse('1234567890123')) 

Will result in [phone] x 123