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

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...