0731 函数

函数：能够独立完成某项功能的模块。

函数四要素：输入、输出、函数体、函数名

在程序设计中，常将一些常用的功能模块编写成函数，放在函数库中工公共选用。

Void是没有返回值的，括号内是参数。

Private只能在当前类里面用，public是公共的，可以在整个命名空间里使用。

函数的注释用三个///

函数定义：

  （static/public）  返回类型 函数名（参数类型 参数名，参数类型 参数名）

{

       函数体

}

将main函数写成函数可以写成4种，无参无返，无参有反，有参有反有参无返。

 例 ：累加求和

无参无返

public void LeiJia()

        {

           

            Console.Write("请输入一个正整数：");

            int a = int.Parse(Console.ReadLine());

            int sum = 0;

            for (int i = 1; i <= a; i++)

            {

                sum += i;

            }

            Console.WriteLine(sum);

            Console.ReadLine();

        }

  static void Main(string[] args)

        {

            Program hanshu = new Program();//首先对于所在的类进行初始化

 

            hanshu.LeiJia();

}

无参有反

  public int LeiJia1()//通过return返回一个int类型的值

        {

        

            Console.Write("请输入一个正整数：");

            int a = int.Parse(Console.ReadLine());

            int sum = 0;

            for (int i = 1; i <= a; i++)

            {

                sum += i;

            }

 

            return sum;

        }

 

  static void Main(string[] args)

        {

            Program hanshu = new Program();//首先对于所在的类进行初始化

int sum = hanshu.LeiJia1();

Console .ReadLine();

}

有参有反

public int LeiJia2(int a)

        {

          

            int sum = 0;

            for (int i = 1; i <= a; i++)

            {

                sum += i;

            }

            return sum;

        }

  static void Main(string[] args)

        {

            Program hanshu = new Program();//首先对于所在的类进行初始化

int sum= hanshu.LeiJia2(5);

 

            Console.WriteLine(sum);

            Console.ReadLine();

}

有参无返

public void LeiJia3(int a)

        {

                       int sum = 0;

            for (int i = 1; i <= a; i++)

            {

                sum += i;

            }

            Console.WriteLine(sum);

            Console.ReadLine();

        }

  static void Main(string[] args)

        {

            Program hanshu = new Program();//首先对于所在的类进行初始化

hanshu.LeiJia3(5);      

  }

 

 

猜拳

            Console.Write("请输入您出什么拳（剪刀、石头、布）：");

            string shu = Console.ReadLine();

 

            if (shu == "剪刀" || shu == "石头" || shu == "布")

            {

                int ren = 0;

                switch (shu)

                {

                    case "剪刀":

                        ren = 1;

                        break;

                    case "石头":

                        ren = 2;

                        break;

                    case "布":

                        ren = 3;

                        break;

                }

                Random ran = new Random();

                int dian = ran.Next(1, 4);

                switch (dian)

                {

                    case 1:

                        Console.WriteLine("电脑出剪刀");

                        break;

                    case 2:

                        Console.WriteLine("电脑出石头");

                        break;

                    case 3:

                        Console.WriteLine("电脑出布");

                        break;

                }

                int jie = ren - dian;

                if (jie == 0)

                {

                    Console.WriteLine("本轮平局！");

                }

                else if (jie == 1 || jie == -2)

                {

                    Console.WriteLine("本轮胜出！");

                }

                else

                {

                    Console.WriteLine("本轮失败！");

                }

            }

            else

            {

                Console.WriteLine("输入有误！");

            }

 

            Console.ReadLine();

 

 

            输入过程中若出错，重新返回输入界面。

            for (int i = 1; i > 0; i++)

            {

                Console.Write("请输入是或者不是！");

                string ss = Console.ReadLine();

                if (ss == "是" || ss == "不是")

                {

                    break;

                }

                else

                {

                    Console.WriteLine("输入有误！请重新输入！");

                }

 }