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?

1
122
10/10/2017 10:07:19 AM

Accepted Answer

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).

243
1/22/2009 7:58:04 PM

You can do it easily with regex:

string subject = "(913)-444-5555";
string result = Regex.Replace(subject, "[^0-9]", ""); // result = "9134445555"

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