有一个汽车类vehicle，它具有一个需传递参数的构造函数，类中的数据成员——车轮个数wheels和车重weight放在保护段protected中；它有一个返回车轮个数的公有函数get_wheels，有一个返回车重的公有函数get_weight，有一个计算每个车轮的承载重量（车重除以车轮数）的公有函数wheel_load，一个公有的打印函数print，它将输出vehicle的车轮数和重量。

小车类car是它的私有派生类，包含一个私有数据成员载客量passenger_load，定义小车类的构造函数，一个获得载客量数目的公有成员函数get_passengers，一个公有的打印函数，它将输出小车的车轮数、重量和载客量。

卡车类truck也是它的私有派生类，包含两个私有数据成员载客量passenger_load和载重量payload，定义卡车类的构造函数，一个获得卡车载客量的公有函数get_passengers，一个获得卡车载重效率的公有函数efficiency（计算方法为载重量/（载重量+卡车本身的重量），一个公有的打印函数print，它将输出卡车的车轮数、重量、载客量和卡车载重效率）。

在car类和truck类中均可以直接访问vehicle类中的wheels和weight。

主函数中定义小车类对象car1(4,1000,5)，卡车类对象tru1(10,5000,3,34000)，然后调用car1和tru1的print函数。-There is a car class vehicle, it has a need to pass parameters to the constructor, the class data members- the number of wheels and vehicle wheels, heavy weight on the protection of the protected segment　it has a number of public functions to return the wheel get_wheels, there is a return to the public function of vehicle weight get_weight, there is a calculation of the weight of each wheel load (vehicle weight divided by the number of wheels) in the public function of wheel_load, a public print function of print, it will output the number and weight of vehicle wheels.

Car class car is its private derived class that contains a private data member patronage passenger_load, the definition of small car class constructor, a number of public access to patronage member functions get_passengers, a public print function, it will output trolley wheel number, weight and capacity.

Pickup truck is also its private derived class contains two private data members of the load carrying capacity p