多重继承与虚基类

由汽车类派生出轿车类和卡车类，再由轿车类和卡车类多重派生出皮卡类。所谓皮卡指的是轿车的后备箱改为卡车似的后厢，可以兼运少量货物。汽车类可以说明为虚基类，以避免在皮卡类中出现两组汽车类的数据，与未说明为虚基类的情况对比。-Multiple inheritance and virtual base classes derived from the auto class cars and trucks category, then by car and truck classes derived class of multi-pickup class. The so-called pickup means the trunk of a car to truck-like rear compartment, and transported to a small amount of goods. Car class can indicate a virtual base class, to avoid appearing in the pickup category two auto data, and did not state the case for the virtual base class comparison.