例题：机选双色球，用到集合，集合里的sort排序，for循环，.Next随机数。知识点很多

 while (true)  

           {

                Random r = new Random();//定义随机数  

               ArrayList red = new ArrayList();//集合类型可以放入

                while (true)

                {

                    if (red.Count == 6)//红球包含六个数

                    {

                        break;//选出六个数就会选择跳出

                    }

                    else

                    {

                        int temp = r.Next(1, 34);//随机选出一个红球

                        if (red.Contains(temp))//选出的红球和上一个红球重复  

                       {

                        }

                        else

                        {

                            red.Add(temp);//如果重复则不要，如果不重复则加入红球中

                        }

                    }  

               }  

               red.Sort();

                Console.Write("红球为;");//输出红球  

               for (int i = 0; i < red.Count; i++)//用循环不断的选出一组组红球

                {

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

                }  

               Console.Write("篮球为" + r.Next(1, 17));//篮球只有一个，所以随机选一个就行

                Console.ReadLine();