例题：请输入一个时间，判断是一天中的哪个时间。逻辑思维比较强的一个题。主要复习一下if else语句

while (true)

            {  

               Console.Write("请输入一个时间(24小时制):");

                  //string   s = Console.ReadLine();

                int hour = Convert.ToInt32(Console .ReadLine ());

                if(hour >= 0 && hour < 6)  

               {  

                   Console.Write("凌晨" + hour + "点");

                }  

               else if(hour >= 6 && hour < 13)

                {

                    Console.Write("上午" + hour + "点");

                }

                else if(hour >= 13 && hour < 19)

                {                    

                 hour = hour - 12;

                    Console.Write("下午" + hour + "点");

                }  

               else if(hour >= 19 && hour < 24)

                {  

                   hour = hour - 12;

                    Console.Write("晚上" + hour + "点");

                }

                else

                {

                    Console.Write("不可识别的时间");

                }

                Console.ReadLine();             }