c# - Replace non-numeric with empty string

Question

Quick add on requirement in our project. A field in our DB to hold a phone number is set to only allow 10 characters. So, if I get passed "(913)-444-5555" or anything else, is there a quick way to run a string through some kind of special replace function that I can pass it a set of characters to allow?

Regex?

Answer 1

Definitely regex:

string CleanPhone(string phone)
{
    Regex digitsOnly = new Regex(@"[^d]");   
    return digitsOnly.Replace(phone, "");
}

or within a class to avoid re-creating the regex all the time:

private static Regex digitsOnly = new Regex(@"[^d]");   

public static string CleanPhone(string phone)
{
    return digitsOnly.Replace(phone, "");
}

Depending on your real-world inputs, you may want some additional logic there to do things like strip out leading 1's (for long distance) or anything trailing an x or X (for extensions).