format a string to usa phone number in vb.net

Question

just as the question says. I get numbers like 2125550938 or 20298277625552. these should change to (212) 555-0938 and (202) 982-7762 x 5552 respectively. this is in vb.net

Answer 1

Dim newNumber As New String
If number.Length = 10 Then
   newNumber = "(" & number.Substring(0, 3) & ") " & number.Substring(2, 3) & "-" & number.Substring(5, 4)
ElseIf number.Length = 14 Then
    newNumber = "(" & number.Substring(0, 3) & ") " & number.Substring(2, 3) & "-" & number.Substring(5, 4) & " x " & number.Substring(9)
End if 

Answer 2

for kyra - the error i am getting is "Index and length must refer to a location within the string. Parameter name: length" newnumber = 2125122121

Answer 3

I would probably go with an implementation of regular expressions, something like this:

    Dim phoneNumbers() As String = {"2125550938", _
        "20298277625552", _
        "2025551212378", _
        "202555131345943"}

    Dim ext As String = ""

    Dim r As New Regex("^(?<AC>\d{3})(?<First>\d{3})(?<Last>\d{4})(?<Ext>\d*$)")
    Dim m As Match

    For i As Int32 = 0 To (phoneNumbers.Length - 1)
        m = r.Match(phoneNumbers(i))
        If m.Groups("Ext").Length > 0 Then
            ext = " x " & CStr(m.Groups("Ext").Value)
        Else
            ext = ""
        End If
        Console.WriteLine("({0}) {1}-{2}{3}", _
            CStr(m.Groups("AC").Value), _
            CStr(m.Groups("First").Value), _
            CStr(m.Groups("Last").Value), ext)
    Next

    Console.Read()

This would allow for phone numbers without extensions or with a variable length extension.

Hope that helps. - Jeff