第16章继承16.1继承概述16.1继承概述2.派生类的声明语法class派生类名：访问控制基类名{数据成员和成员函数声明}；例如，汽车类vehicle和其派生类小车类car的定义：classvehicle{intwheels;//车轮数floatweight;//汽车重量public:voidinitialize(intin_wheels,floatin_weight);//初始化数据成员intget_wheels();//获取车轮数floatget_weight();//获取车重floatget_loading();//车轮承重}；classcar:vehicle//缺省声明，私有继承{intpassenger_load://载客量public:voidinitialize(intin_wheels,floatin_weight,intpeople=4);intpassengers();//返回载客数}；派生类对基类成员可以有不同的访问方式：派生类可以覆盖基类成员派生类不能访问基类私有成员公有继承基类的公有段和保护段成员访问权对派生类保持不变私有继承基类的公有段和保护段成员成为派生类的私有成员如果派生类定义了与基类同名的成员，称派生类的成员覆盖了基类的同名成员若要在派生类中使用基类同名成员，可以显式地使用类名限定符：类名::成员例：classbase{public:inta,b;};classderived:publicbase{public:intb,c;};voidf(){derivedd;d.a=1;d.base::b=2;//base::b使用的是base类的数据成员bd.b=3;//这里使用的是derived类的数据成员bd.c=4;};例：classX{public:voidget_ij();voidput_ij();private:inti,j;};classY:publicX{public:intget_k();voidmake_k();private:intk;};voidY::make_k();{k=i*j;//非法};classX{public:voidget_ij();voidput_ij();};classY:publicX{public:intget_k();voidmake_k();private:intk;};voidY::make_k();{};3.公有继承例：//ex16_1classX{protected:inti,j;public:voidget_ij(){cout<<“Entertwonumbers:”;cin>>i>>j;};voidput_ij(){cout<<i<<“”<<j<<‘\n’;};};classY:publicX{intk;public:intget_k(){returnk;};voidmake_k(){k=i*j;};//使用基类成员i，j};classZ:publicY{public:voidf(){i=2;j=3;};//使用基类成员i，j};main(){Yvar1;Zvar2;var1.get_ij();var1.put_ij();var1.make_k();var2.f();var2.put_ij();}例：//ex16_1classX{protected:inti,j;public:voidget_ij(){cout<<“Entertwonumbers:”;cin>>i>>j;};voidput_ij(){cout<<i<<“”<<j<<‘\n’;};};classY:publicX{intk;public:intget_k(){returnk;};voidmake_k(){k=i*j;};//使用基类成员i，j};classZ:publicY{public:voidf(){i=2;j=3;};//使用基类成员i，j};main(){Yvar1;Zvar2;var1.get_ij();var1.put_ij();var1.make_k();var2.f();var2.put_ij();}4.私有继承保护继承//ex16_2classX{protected:inti,j;public:voidget_ij(){cout<<“Entertwonumbers:”;cin>>i>>j;};voidput_ij(){cout<<i<<“”<<j<<‘\n’;};};class