函数输出多个返回值

   public int chengfa(int a, int b, out int c, out int d)
        {
            int i = a * b;
            c = a - b;
            d = a + b;
            return i;
        }

        static void Main(string[] args)
        {
            int c;
            int d;
            int i = new Program().chengfa(4, 5, out c, out d);
            Console.WriteLine(i);
            Console.WriteLine(c);
            Console.WriteLine(d);
        }