继续上面的学习，这次的是流程控制，用dowhile，代码如下，还是用语言选择来作为事例的。
using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication9
{
        class Program
        {
                static void Main(string[] args)
                {
                        Console.WriteLine("欢迎进入语言选择：");

                        string Language;
                        do    
                        {
                                Console.WriteLine("==================>");
                                Language = Console.ReadLine();
                                switch(Language)
                                {
                                        case "C":
                                                selectC();
                                                break;
                                        case "Delphi":
                                                selectDelphi();
                                                break;
                                        case "Java":
                                                selectJava();
                                                break;
                                        default :
                                                selectDefault();
                                                break;                                
                                }                                
                        } while(Language!="exit");//这边的（！=）不能写成（<>），我第一次写的时候就习惯性写错了


                }

                private static int selectDelphi()
                {
                        Console.WriteLine("你选择的是Delphi语言");
                        return 0;
                }
                private static int selectJava()
                {
                        Console.WriteLine("你选择的是Java");
                        return 0;
                }
                private static int selectC()
                {
                        Console.WriteLine("你选择的是C语言");
                        return 0;
                }
                private static int selectDefault()
                {
                        Console.WriteLine("你的选择只有三个：");
                        Console.WriteLine("C");
                        Console.WriteLine("Java");
                        Console.WriteLine("Delphi");
                        Console.WriteLine("exit为退出");
                        Console.WriteLine("=================>");
                        return 0;    
                }
        }

}