{ passenger_load=number; payload=max_load; }
double truck::efficiency() { return payload/(payload+weight); }
void main() { vehicle bicycle; bicycle.initialize(2,25); cout<<\ cout<<\ cout<<\ car audi; audi.initialize(4,3500.0,5); cout<<\ cout<<\ cout<<\ truck jief; jief.initialize(18,12500.0); jief.init_truck(2,33675.0);
cout<<\ cout<<\ cout<<\}
[基本要求]
? 上机录入、调试上面程序。
? 运行程序，观察运行结果是否正确且满足题意要求。
? 将class car: public vehicle和class truck: public vehicle分别改为： class car: private vehicle和class truck: private vehicle 程序运行结果有无变化，为什么？ [分析与思考]
? 定义并实现vehicle类、car类和truck类的构造函数，完成vehicle类、car类和truck类的数据成员初始化工作。
? 将vehicle中数据成员wheels和weight改为private性质，如何修改程序以达到相同的输出结果。
（2）下面程序对应图1所示的类层次继承结构: #include
class person {
protected:
char name[20];
in-service_graduate int birth_year;
public:
person(char *na, int year) { strcpy(name,na); birth_year=year; }
int cal_age(int this_year) {
return this_year-birth_year; } };
class graduate :public person {
protected: int grade;
char specialty[20]; public:
graduate(char *na, int y, int g, char *spec):person(na,y) { grade=g; strcpy(specialty,spec); }
void display(int this_year) { cout<<\ graduate age grade specialty\\n\ cout< class teacher :public person { protected: char title[15]; char specialty[20]; public: teacher(char *na, int y, char *ti, char *spec):person(na,y) { strcpy(title,ti); teacher graduate strcpy(specialty,spec); } void display(int this_year) { cout<<\ teacher age title specialty\\n\ cout< }; class in_service_graduate:public teacher, public graduate { public: in_service_graduate(char *na, int y, char *ti, char *spec1, int g, char *spec2): teacher(na, y, ti, spec1), graduate(na, y, g, spec2) { } void display(int this_year) { cout<<\ age title work_specialty grade study_specialty\\n\cout< } }; void main() { graduate gr(\ teacher te(\ in_service_graduate sg(\ gr.display(2002); cout< sg.display(2002); } [基本要求] ? 阅读程序，完成in_service_graduate类中的display()函数的程序。 ? 上机录入、调试上面程序。 ? 运行程序，观察运行结果是否正确且满足题意要求。 [分析与思考] ? 在上面程序中类person中的数据成员name和birth_year在in_service_graduate类中有两个副本，请使用虚基类使它们在in_service_graduate类中只有一个副本。注意同时修改程序的其他相关部分。 4.源代码 1. #include protected: int wheels; double weight; public: vehicle(int x,double y){wheels=x;weight=y;} int get_wheels() { return wheels; } double get_weight() { return weight; } double wheel_loading() { return weight/wheels; } }; class car: public vehicle { private: int passenger_load; public:car(int x,double y,int z=4):vehicle(x,y) {passenger_load=z;} // void initialize(int whls, double wght, int people=4 ); int passengers() { return passenger_load; } }; class truck: public vehicle { private: int passenger_load; double payload; public: truck(int x,double y,int z=2,double w=24000.0):vehicle(x,y) {passenger_load=z;payload=w;} // void init_truck(int number =2, double max_load =24000.0); double efficiency(); int passengers() { return passenger_load; } }; double truck::efficiency() { return payload/(payload+weight); }