How do I start a program with arguments when debugging?

I would suggest using the directives like the following:

        static void Main(string[] args)
        {
#if DEBUG
            args = new[] { "A" };
#endif

            Console.WriteLine(args[0]);
        }

Good luck!

Go to Project-><Projectname> Properties. Then click on the Debug tab, and fill in your arguments in the textbox called Command line arguments.