函数及其调用

class Program
    {
        public void dayin()
        {
            Console.WriteLine("hollo world");
        }
        /// <summary>
        /// 累加求和
        /// </summary>
        /// <param name="n"></param>
        /// <returns></returns>
        public int leijia(int n)
        {
            int sum = 0;
            for (int i = 1; i <= n;i++ )
            {
                sum += i;
            }
            return sum;
        }
        /// <summary>
        /// 输入一个数判断是不是质数
        /// </summary>
        /// <param name="n"></param>
        /// <returns></returns>
        public void zhishu(int n)
        {
            int count = 0;
            for (int i = 1; i <= n;i++ )
            {
                if(n%i==0)
                {
                    count++;
                }
            }
            if (count == 2)
            {
                Console.WriteLine("质数");
            }
            else
            {
                Console.WriteLine("不是质数");
            }
        }

        /// <summary>
        /// 求阶乘及其的和
        /// </summary>
        /// <param name="n"></param>
        /// <returns></returns>
        public void jiecheng(int n)
        {
            int jiecheng = 1;
            int he = 0;
            for (int i = 1; i <=n; i++)
            {
                jiecheng *= i;
                he = he + jiecheng;
            }
            Console.WriteLine("阶乘是"+jiecheng+"阶乘的和是"+he);
        }
        /// <summary>
        /// 猜拳三局两胜
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        public void caiquan()
        {

            int renying = 0;
            int diannaoying = 0;
            for (int i = 1; i <= 3; i++)
            {
                Console.Write("请输入人出拳（0-剪刀，1-石头，2-布）a=");
                int a = int.Parse(Console.ReadLine());
                Random r = new Random();
                int b = r.Next(3);
                Console.WriteLine("电脑出拳（0-剪刀，1-石头，2-布）b=" + b);

                if (a - b == 1 || a - b == -2)
                {
                    renying++;
                   Console.WriteLine("人赢一局");
                }
                else if (a == b)
                {
                    Console.WriteLine("平局");
                    i--;
                    continue;
                }
                else
                {
                    diannaoying++;
                    Console.WriteLine("电脑赢一局");
                }
                if (renying >= 2)
                {
                    Console.WriteLine("三局两胜人赢");
                    break;
                }
                else if (diannaoying >= 2)
                {
                    Console.WriteLine("三局两胜电脑赢");
                    break;
                }
            }
        }
        //主函数
        static void Main(string[] args)
        {
            while (true)
            {
                new Program().dayin();
                Console.WriteLine("请输入一个正整数");
                int n = int.Parse(Console.ReadLine());

                int jieguo = new Program().leijia(n);
                Console.WriteLine(jieguo);
                new Program().zhishu(n);
                new Program().jiecheng(n);
                new Program().caiquan();
                Console.ReadLine();
            }
        }
    }