一个关于停车场的管理系统，统计车辆进出的记录-One on the car park management systems, statistical records of vehicles entering and leaving

简易二手车管理系统 可添加删除车辆、修改车辆具体信息（车型、厂家、型号、购入时间、购入价格、是否售出、售出价格）、将车辆信息保存到外部文档、从外部文档读取车辆信息-System Design Class car: includes car’s self-attributes, such as its number, logo, price.etc. Class DataStream: includes 2 methods, readData() and saveDa