formatting string in MVC /C#

Question

I have a string 731478718861993983 and I want to get this 73-1478-7188-6199-3983 using C#. How can I format it like this ?

Thanks.

Answer 1

If the position of "-" is always the same then you can try

string s = "731478718861993983";
s = s.Insert(2, "-");
s = s.Insert(7, "-");
s = s.Insert(12, "-");
s = s.Insert(17, "-"); 

Answer 2

Here's how I'd do it; it'll only work if you're storing the numbers as something which isn't a string as they're not able to be used with format strings.

string numbers = "731478718861993983";
string formattedNumbers = String.Format("{0:##-####-####-####-####}", long.Parse(numbers));

Edit: amended code, since you said they were held as a string in your your original question

Answer 3

My first thought is:

String s = "731478718861993983";
s = s.Insert(3,"-");
s = s.Insert(8,"-");
s = s.Insert(13,"-");
s = s.Insert(18,"-");

(don't remember if index is zero-based, in which case you should use my values -1) but there is probably some easier way to do this...

Answer 4

string s = "731478718861993983"
var newString = (string.Format("{0:##-####-####-####-####}", Convert.ToInt64(s));

Answer 5

If you're dealing strictly with a string, you can make a simple Regex.Replace, to capture each group of 4 digits:

string str = "731478718861993983";
str = Regex.Replace(str, "(?!^).{4}", "-$0" ,RegexOptions.RightToLeft);
Console.WriteLine(str);

Note the use of RegexOptions.RightToLeft, to start capturing from the right (so "12345" will be replaced to 1-2345, and not -12345), and the use of (?!^) to avoid adding a dash in the beginning.
You may want to capture only digits - a possible pattern then may be @"\B\d{4}".

Answer 6

If you're dealing with a long number, you can use a NumberFormatInfo to format it:

First, define your NumberFormatInfo (you may want additional parameters, these are the basic 3):

NumberFormatInfo format = new NumberFormatInfo();
format.NumberGroupSeparator = "-";
format.NumberGroupSizes = new[] { 4 };
format.NumberDecimalDigits = 0;        

Next, you can use it on your numbers:

long number = 731478718861993983;
string formatted = number.ToString("n", format);
Console.WriteLine(formatted);

After all, .Net has very good globalization support - you're better served using it!