#include <iostream> /* run this program using the console pauser or add your own getch, system("pause") or input loop */ class A { public: virtual int getMile() { return getPerGallon() * getGallon(); } virtual void setGallon(int gallon) { mGallon = gallon; } virtual int getGallon() { return mGallon; } private: int mGallon; virtual int getPerGallon() { return 20; } }; class B : public A { public: virtual int getPerGallon() { return 35; } }; int main(int argc, char** argv) { B b; A a; b.setGallon(2); a.setGallon(2); std::cout << "B have ride " << b.getMile() << std::endl; std::cout << "A have ride " << a.getMile() << std::endl; /* B have ride 70 A have ride 40 */ return 0; }
虚函数不仅可以定义在public,而且可以声明在protected和private里边
而在派生类里边可以定义在任何限定里边,不一定和父类的限制符相同,比如:父类的在private里,但是子类可以定义在public里