[调研报告]C++实验三报告.docVIP

1.声明一个基类Shape，在次基础上派生出Rectangle和Circle，二者都有GetArea（）函数计算对象的面积。使用Rectangle创建一个派生类Square。 程序清单： #includeiostream.h const double PI=3.14; class Shape //定义基类 { public: Shape(){}; virtual double GetArea() const{return 0.0;} //定义虚函数 }; class Rectangle:public Shape //定义派生类 { public: Rectangle(double l,double w) {len=l;wid=w;} virtual double GetArea() const{return len*wid;} protected: double len,wid; }; class Circle:public Shape //定义派生类 { public: Circle(double r){R=r;} virtual double GetArea() const{return PI*R*R;} protected: double R; }; class Square:public Rectangle //定义派生类 { public: Square(double a):Rectangle(a,a){} virtual double GetArea() const{return len*wid;} }; void func(Shape p) //形参为基类的引用 { coutp.GetArea()endl; } int main() { Rectangle r(1.32,4); coutArea of Rectangle is:; func(r); Circle c(12.3); coutArea of Circle is:; func(c); Square s(11); coutArea of Square is:; func(s); return 0; } 2.声明一个object类，有数据成员weight及相应的操作函数，由此派生出box类，增加数据成员height和width及相应的操作函数，声明一个box对象，实现并测试这些类，同时观察构造函数和析构函数的调用顺序。 #include iostream using namespace std; class object { private: float weight; public: object():weight(0) { cout the constructor of object is called. endl; } ~object() { cout the destructor of object is called. endl; } float getweight() { return weight; } void setweight(float newweight) { weight = newweight; } }; class box: public object { private: float hight,width; public: box():hight(0),width(0) { cout the constructor of box is called. endl; } ~box(){ cout the destructor of box is called. endl; } float gethight() { return hight; } void sethight(float newhight){ hight = newhight; } float getwidth() { return width; } void setwidth(float newwidth){ width = newwidth; } }; int main(){ box box1; cout the weight is box1.getweight() endl; cout the hight is box1.gethight() endl; cout the width is box1.getwidth() en