例题：把机选双色球做成函数题。public定义函数，可以定义多种类型，也可以定义集合，学习函数题多一种方法。

public ArrayList jixuanqiu(ArrayList red)   //定义一个集合类型的函数

        {

            Random r = new Random();  //机选6个红球的过程并排序

            while (true)

            {

                if (red.Count == 6)

                {

                    break;

                }

                else

                {

                    int temp = r.Next(1, 34);

                    if (!red.Contains(temp))

                    {

                        red.Add(temp);

                    }

                }

            }  

           red.Sort();

            return red;

        }  

       static void Main(string[] args)

        {

                      while (true)

            {

                 Random r = new Random();

                ArrayList red = new ArrayList();

                new Program().jixuanqiu(red);

           //输出函数                

                Console.Write("红球为：");

                for (int i = 0; i < 6; i++)

                {  

                   Console.Write(red[i] + " ");

                }

                Console.Write("蓝球为：" + r.Next(1, 17));

                Console.ReadLine();

            }