Formatting a Phone number

Question

How can I format a phone number from (###)###-#### to ##########? Is there best way to do that? I can use String.Substring to get each block of numbers and then concatenate them. But, Is there any other sophisticated way of doing it?

score 3 · Accepted Answer · answered May 08 '14 at 15:12

3

How about a simple Regex replace?

string formatted = Regex.Replace(phoneNumberString, "[^0-9]", "");

This is essentially just a white list for numbers only. See this fiddle: http://dotnetfiddle.net/ssdWSd

Input: (123) 456-7890

Output: 1234567890

answered May 08 '14 at 15:12

tnw

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The `+` is unnecessary, as the function will look for all substrings which satisfy the regex specified and replace it. – wei2912 May 08 '14 at 15:14
@wei2912 You're right, fixed. – tnw May 08 '14 at 15:15

score 3 · Answer 2 · answered May 08 '14 at 15:13

3

I'd do it using LINQ:

var result = new String(phoneString.Where(x => Char.IsDigit(x)).ToArray());

While regex also works, this doesn't require any special set up.

answered May 08 '14 at 15:13

Nathan A

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dckuehn · Answer 3 · 2014-05-08T15:33:48.827

0

A simple way would be:

myString = myString.Replace("(", "");
myString = myString.Replace(")", "");
myString = myString.Replace("-", "");

Replace each character with an empty string.

edited May 08 '14 at 15:33

answered May 08 '14 at 15:12

dckuehn

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This won't work as it assumes strings are mutable, which they aren't. – Daniel Kelley May 08 '14 at 15:19
I always forget that. Does my edit work? – dckuehn May 08 '14 at 15:34
It would work now. The -1 is not from me. – Daniel Kelley May 08 '14 at 15:42
It's cool. It was wrong earlier, and whoever it was probably won't come back. I can't believe how often I forget strings aren't mutable in c#. Sometimes it takes me 15 minutes of debugging before it hits me. – dckuehn May 08 '14 at 15:55

score -1 · Answer 4 · answered May 08 '14 at 15:13

Try this:

resultString = Regex.Replace(subjectString, @"^\((\d+)\)(\d+)-(\d+)$", "$1$2$3");

REGEX EXPLANATION

^\((\d+)\)(\d+)-(\d+)$

Assert position at the beginning of the string «^»
Match the character “(” literally «\(»
Match the regex below and capture its match into backreference number 1 «(\d+)»
   Match a single character that is a “digit” (0–9 in any Unicode script) «\d+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Match the character “)” literally «\)»
Match the regex below and capture its match into backreference number 2 «(\d+)»
   Match a single character that is a “digit” (0–9 in any Unicode script) «\d+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Match the character “-” literally «-»
Match the regex below and capture its match into backreference number 3 «(\d+)»
   Match a single character that is a “digit” (0–9 in any Unicode script) «\d+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Assert position at the end of the string, or before the line break at the end of the string, if any (line feed) «$»

$1$2$3

Insert the text that was last matched by capturing group number 1 «$1»
Insert the text that was last matched by capturing group number 2 «$2»
Insert the text that was last matched by capturing group number 3 «$3»

Care to explain the down-vote ? – Pedro Lobito May 08 '14 at 15:14 — Pedro Lobito, May 08 '14 at 15:14

Formatting a Phone number

4 Answers4