递归

 class Program
    {
        public void digui(int i)
        {
            Console.Write("hello"+i);
            if (i == 10)
            {
                return;
            }
            i++;
            digui(i);
        }


        public int ganyang(int cun)
        {
            if (cun == 7)
            {
                return 2;
            }

            int sum = (ganyang(cun + 1) + 1) * 2;

            return sum;
        }

        //

        static void Main(string[] args)
        {

            new Program().digui(0);

            Console.WriteLine(new Program().ganyang(0));
            Console.ReadLine();
        }
    }