(一) 實現(xiàn)登錄功能

1. 需求說明
   (1) . 輸入注冊時的用戶名和密碼，登錄成功，提示歡迎信息
   (2) . 如果用戶名和密碼輸入錯誤，提示用戶繼續(xù)輸入，最多有3次輸入機會
   int max = 99999;
   int min = 1000;
   Random rd = new Random();
   rd.Next(min, max);
   int a = 0;
   string user = "";
   string key = "";
   string b = "";
   Console.WriteLine("*****歡迎進入獎客富翁系統(tǒng)*****");
   Console.WriteLine(" 1.注冊");
   Console.WriteLine(" 2.登錄");
   Console.WriteLine(" 3.抽獎");
   Console.WriteLine("******************************");
   Console.WriteLine("請選擇菜單：");
   a = Convert.ToInt32(Console.ReadLine());
   switch (a)
   {
   case 1:
   Console.WriteLine("[獎客富翁系統(tǒng)>注冊]");
   Console.WriteLine("請?zhí)顚懹脩糇孕畔?");
   Console.WriteLine("用戶名:");
   user = Console.ReadLine();
   Console.WriteLine("密碼:");
   key = Console.ReadLine();
   Console.WriteLine("注冊成功，請記好你的會員卡號");
   Console.WriteLine("用戶名\t\t密碼\t\t會員卡號");
   Console.WriteLine("{0}\t\t{1}\t\t{2}", user, key, rd.Next(min, max));
   Console.WriteLine("繼續(xù)嗎?(y/n)");
   b = Console.ReadLine();
   break;
   case 2:
   Console.WriteLine("[獎客富翁系統(tǒng)>登錄]");
   user = "admin";
   key = "123456";
   int i = 2;
   while (i > -1)
   {
   Console.WriteLine("請輸入用戶名:");
   string yonghu = Console.ReadLine();
   Console.WriteLine("請輸入密碼:");
   string mima = Console.ReadLine();
   if (user == yonghu & key == mima & i > 0)
   {
   Console.WriteLine("歡迎您:{0}", yonghu);
   break;
   }
   else
   {
   if (i > -1)
   {
   Console.WriteLine("你還剩{0}次機會", i);
   i--;
   continue;
   }
   else
   {
   Console.WriteLine("你的機會用完了");
   break;
   }
   }
   }
   break;
   case 3:
   Console.WriteLine("[獎客富翁系統(tǒng)>抽獎]");
   break;
   }
   Console.WriteLine("繼續(xù)嗎？（y/n）");
   b = Console.ReadLine(); switch (b)
   {
   case "n":
   Console.WriteLine("系統(tǒng)退出，謝謝使用");
   break;
   case "y":
   Console.WriteLine("");
   break;
   }
   Console.ReadKey();