place a comma after each 3 digit in a 9 digit numbe in c#?

Question

Possible Duplicates:
.NET String.Format() to add commas in thousands place for a number
Add comma to numbers every three digits using C#

I want to create a logic in c# too put the comma after each 3 digit int the any 9 digit number, could any body tel me how can i achieve this?

Like i have the following number 123456789 then i want to form it like 123,456,789.

Answer 1

Call ToString and specify "N" as the format string

Answer 2

var formattedString = string.Format("{0:0,0}", 123456789);

Answer 3

double value = 1234567890;
Console.WriteLine(value.ToString("#,#", CultureInfo.InvariantCulture));