Regex – Phone Numbers

Here is a useful RegEx (.Net) expression to find U.S. phone numbers:

^(?:(?:[\+]?(?<CountryCode>[\d]{1,3}(?:[ ]+|[\-.])))?[(]?(?<AreaCode>[\d]{3})[\-/)]?(?:[ ]+)?)?
(?<Number>(?<Number1>[a-zA-Z0-9]{3})
(?:[\-. ]?)
(?<Number2>[a-zA-Z0-9]{4,}))
(?:[ \-](?:(?:[xX]|ext)[ \-](?<extn>\d{2,5})))?
$

It finds the following formats of numbers:

313-625-6860
(301) 621-6862
1234567890
111 222 3333
(111)-222-3333
1-800-333-4444
327-6116
1-800-REGEXLIB
(610) 310-5555 x 55
(610) 310-5555 ext 55
1 610 310 5555 ext-555
+1 610 310 5555 ext-555

The regex breaks down the phone number into the following groups:

Here is how the Regulator’s RegEx analyzer explains it:

^ (anchor to start of string)
Non-capturing Group
  Non-capturing Group
    Any character in "\+"
    ? (zero or one time)
    Capture to <CountryCode>
      Any character in "\d"
      At least 1, but not more than 3 times
      Non-capturing Group
        Any character in " "
        + (one or more times)
                or
        Any character in "\-."
      End Capture
    End Capture
  End Capture
  ? (zero or one time)
  Any character in "("
  ? (zero or one time)
  Capture to <AreaCode>
    Any character in "\d"
    Exactly 3 times
  End Capture
  Any character in "\-/)"
  ? (zero or one time)
  Non-capturing Group
    Any character in " "
    + (one or more times)
  End Capture
  ? (zero or one time)
End Capture
? (zero or one time)


Capture to <Number1>
  Any character in "a-zA-Z0-9"
  Exactly 3 times
End Capture


Non-capturing Group
  Any character in "\-. "
  ? (zero or one time)
End Capture


Capture to <Number2>
  Any character in "a-zA-Z0-9"
  At least 4 times
End Capture


Non-capturing Group
  Any character in " \-"
  Non-capturing Group
    Non-capturing Group
      Any character in "xX"
            or
      ext
    End Capture
    Any character in " \-"
    Capture to <extn>
      Any digit 
      At least 2, but not more than 5 times
    End Capture
  End Capture
End Capture
? (zero or one time)

$ (anchor to end of string)

And here is the code to use it:

private void Test()
        {
            string regex = "^(?:(?:[\\+]?(?<CountryCode>[\\d]{1,3}(?:[ ]+|[\\-.])))?[(]?(?<AreaCode>[\\d]{3})[\\-/" +
")]?(?:[ ]+)?)?\r\n(?<Number>(?<Number1>[a-zA-Z0-9]{3})\r\n(?:[\\-. ]?)\r\n(?<Number2>[a" +
"-zA-Z0-9]{4,}))\r\n(?:[ \\-](?:(?:[xX]|ext)[ \\-](?<extn>\\d{2,5})))?\r\n$";
            System.Text.RegularExpressions.RegexOptions options = ((System.Text.RegularExpressions.RegexOptions.IgnorePatternWhitespace | System.Text.RegularExpressions.RegexOptions.Multiline) 
                        | System.Text.RegularExpressions.RegexOptions.IgnoreCase);
            System.Text.RegularExpressions.Regex reg = new System.Text.RegularExpressions.Regex(regex, options);
        }