函数和小练习

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace 练习函数
{
    class Program
    {
        //阶乘累加求和
        //1.又返回值 ，并且有参数
        public int jie(int z)
        {
            int sum = 0;
            int jie = 1;
            for (int i = 1; i <= z; i++)
            {
                jie *= i;
                sum += jie;
            }
            return sum;

        }
        static void Main(string[] args)
        {
            Program hanshu = new Program();

            Console.Write("输入一个整数:");
            int a = int.Parse(Console.ReadLine());
            hanshu.jie(a);
            int sum = hanshu.jie(a);
            Console.WriteLine(sum);
            Console.ReadLine();
        }

        //2.有返还值，没有参数
        public int jie1()
        {
            Console.Write("输入一个整数");
            int a = int.Parse(Console.ReadLine());
            int sum = 0;
            int jie = 1;
            for (int i = 1; i <= a; i++)
            {
                jie *= i;
                sum += jie;
            }
            return sum;

        }
        static void Main(string[] args)
        {
            Program hanshu = new Program();
            int sum = hanshu.jie1();

            Console.WriteLine(sum);
            Console.ReadLine();


        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Hanshu
{
    class Program
    {
        //没有返回值，没有参数
        public void aa()
        {
            Console.WriteLine("Hello world!");
        }

        //没有返回值，没有参数
        public void Leijia()
        {
            //累加求和
            Console.Write("请输入一个整数：");
            int a = int.Parse(Console.ReadLine());
            int sum = 0;
            for (int i = 1; i <= a; i++)
            {
                sum += i;
            }
            Console.WriteLine(sum);
        }
        
        //没有返回值，有参数
        public void Leijia(int z)
        {
            int sum = 0;
            for (int i = 1; i <= z; i++)
            {
                sum += i;
            }
            Console.WriteLine(sum);
        }

        //有返回值，并且有参数
        public int Leijia1(int z)
        {
            int sum = 0;
            for (int i = 1; i <= z; i++)
            {
                sum += i;
            }
            return sum;
        }
        //有返回值，没有参数
        public int Leijia2()
        {
            Console.Write("请输入一个整数：");
            int a = int.Parse(Console.ReadLine());
            int sum = 0;
            for (int i = 1; i <= a; i++)
            {
                sum += i;
            }
                return sum;
        }

        /// <summary>
        /// 两个值进行比较，返回较大的，若相等，返回任意一个
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public double MAX(double a,double b)
        {
            if (a > b)
            {
                return a;
            }
            else
            {
                return b;
            }
        }



        static void Main(string[] args)
        {
            //初始化这个类，是为了调用这个类里面的函数
            Program hanshu = new Program();
            //hanshu.aa();
            //函数必须经过调用才能执行


            //hanshu.Leijia();

            //Random ran = new Random();
            //int aa =ran.Next(10);



            //累加求和
            //Console.Write("请输入一个整数：");
            //int a = int.Parse(Console.ReadLine());
            ////hanshu.Leijia(a);

            //int sum= hanshu.Leijia1(a);
            //Console.WriteLine(sum);

            //int sum= hanshu.Leijia2();
            //Console.WriteLine(sum);

            double a = 4, b = 7, c = 2;
            Console.WriteLine(hanshu.MAX(hanshu.MAX(a,b),c));




                Console.ReadLine();
        }
    }
}