Question

I have a string and want to add some hypens in the middle. I know I can use Substring or something, but want to be sure that I can not use String.Format or other native function to do the job.

String.Format("{0:###-###}", "ABCDEF"); //  <-- does not work

Answer 1

Or you can use the Insert method from string such as below

Console.WriteLine("ABCDEF".Insert(3, "-"));

You can work out the insert position instead of hard coding above by simply divide the length/2