任务：通过此系统可以实现如下功能：

录入：可以录入航班情况（数据可以存储在一个数据文件中，数据结构、具体数据自定）

查询：可以查询某个航线的情况（如，输入航班号，查询起降时间，起飞抵达城市，航班票价，票价折扣，确定航班是否满仓）；

可以输入起飞抵达城市，查询飞机航班情况；

订票：（订票情况可以存在一个数据文件中，结构自己设定）

可以订票，如果该航班已经无票，可以提供相关可选择航班；

退票：可退票，退票后修改相关数据文件；

客户资料有姓名，证件号，订票数量及航班情况，订单要有编号。

修改航班信息：当航班信息改变可以修改航班数据文件-task : the system can achieve the following functions : recording : Input can flights (data can be stored in a data file, the data structure, specific data set) Inquiries : Inquiries can be a route (for example, the importation of flight, take-off and landing time inquiries, arrived in town to take off, flight fares, discount fares, flights to determine whether the Mancang); can import arrived in town to take off, inquiries flights; booking : (booking situation may exist a data file, the structure of their own creation) could booking, if the flight has no vote, can provide the option of flights; Refund : Refund available, a refund after the revision of relevant data files; Customer information name, documents, booking flights and the number of orders have numbered. Revised flight informati