//去掉DEFAULT这句话就没有问题。。。。。。
//添加上就会有:
//错误 CS0163: 控制不能从一个 case 标签(“default:”)贯穿到另一个 case 标签
using System;
using System.Collections.Generic;
using System.Text;

namespace onmethod
{
    class onemethod
    {
        static void Main(string[] args)
        {
            string mychoies;
            onemethod om = new onemethod();
            do
            {
                mychoies = om.getchoice();
                //根据选择出的结果做决定
                switch (mychoies)
                {
                    case "A":
                    case "a":
                        Console.WriteLine(" 你想添加一个书签");
                        break;
                    case "D":
                    case "d":
                        Console.WriteLine("你想 删除一个书签");
                        break;
                    case "M":
                    case "m":
                        Console.WriteLine("你想整理书签");
                        break;
                    case "Q":
                    case "q":
                        Console.WriteLine("再见");
                        break;
                    case "V":
                    case "v":
                        Console.WriteLine("你想浏览书签");
                        break;
                    default :
                        Console.WriteLine("不存在这个命令");
                }
                //让用户查看结果
                Console.WriteLine("按任意键继续。。。。");
                Console.ReadLine();
            } while (mychoies != "Q" && mychoies != "q");
        }
        string getchoice()
        {
            string mychoice;
            //打印菜单
            Console.WriteLine("我的一个收藏地址是：\n");
            Console.WriteLine("A-添加一个新书签\n");
            Console.WriteLine("D-删除一个书签\n");
            Console.WriteLine("M-整理书签\n");
            Console.WriteLine("V-整理书签\n");
            Console.WriteLine(" Q-推出\n");
            Console.WriteLine(" 选择：A,D,M,V,Q");
            mychoice = Console.ReadLine();
            return mychoice;
        }
    }
}