第六章习题汇总

1.

#include <iostream>     using namespace std;  #include "cylinder.h"#include "point.cpp"#include "circle.cpp"#include "cylinder.cpp"int main(){Cylinder cy1(3.5,6.4,5.2,10); cout<<"\noriginal cylinder:\nx="<<cy1.getX()<<", y="<<cy1.getY()<<", r="<<cy1.getRadius()<<", h="<<cy1.getHeight()<<"\narea="<<cy1.area()<<", volume="<<cy1.volume()<<endl; cy1.setHeight(15); cy1.setRadius(7.5); cy1.setPoint(5,5); cout<<"\nnew cylinder:\n"<<cy1; Point &pRef=cy1; cout<<"\npRef as a point:"<<pRef; Circle &cRef=cy1; cout<<"\ncRef as a Circle:"<<cRef; return 0;}

3.

(1)#include <iostream>using namespace std;class Point{public:  Point(float a,float b):x(a),y(b){}  ~Point(){cout<<"executing Point destructor"<<endl;} private:  float x;  float y;};class Circle:public Point{public: Circle(float a,float b,float r):Point(a,b),radius(r){}  ~Circle(){cout<<"executing Circle destructor"<<endl;} private:  float radius;};int main(){Point *p=new Circle(2.5,1.8,4.5); delete p; return 0;}

(2)#include <iostream>using namespace std;class Point{public:  Point(float a,float b):x(a),y(b){}  ~Point(){cout<<"executing Point destructor"<<endl;} private:  float x;  float y;};class Circle:public Point{public:Circle(int a,int b,int r):Point(a,b),radius(r){}  ~Circle(){cout<<"executing Circle destructor"<<endl;} private:  float radius;};int main(){Point *p=new Circle(2.5,1.8,4.5); Circle *pt=new Circle(2.5,1.8,4.5); delete pt; return 0;}

(3)#include <iostream>using namespace std;class Point{public:  Point(float a,float b):x(a),y(b){}  virtual ~Point(){cout<<"executing Point destructor"<<endl;} private:  float x;  float y;};class Circle:public Point{public:Circle(float a,float b,float r):Point(a,b),radius(r){}  virtual ~Circle(){cout<<"executing Circle destructor"<<endl;} private:float radius;};void main(){Point *p=new Circle(2.5,1.8,4.5); delete p;}

 

 

4.#include <iostream>using namespace std;class Shape{public:virtual double area() const =0;            };class Circle:public Shape{public:Circle(double r):radius(r){}                                      virtual double area() const {return 3.14159*radius*radius;};   protected:  double radius;                                                 }; class Rectangle:public Shape{public: Rectangle(double w,double h):width(w),height(h){}                virtual double area() const {return width*height;}             protected:  double width,height;                                           };class Triangle:public Shape{public:  Triangle(double w,double h):width(w),height(h){}                  virtual double area() const {return 0.5*width*height;}           protected:  double width,height;                                            };void printArea(const Shape &s){cout<<s.area()<<endl;}                                        int main(){ Circle circle(1);                                             cout<<"圆的面积为:";           printArea(circle);                                            Rectangle rectangle(3,4);                                     cout<<"矩形的面积为：";                                      printArea(rectangle);                                             Triangle triangle(4,5);  cout<<"三角形的面积为："; printArea(triangle);          return 0;}

5.#include <iostream>using namespace std;class Shape{public: virtual double area() const =0;                                };class Circle:public Shape{public:Circle(double r):radius(r){}                                       virtual double area() const {return 3.14159*radius*radius;};    protected:  double radius;                                                 };class Square:public Shape{public:  Square(double s):side(s){}                                   virtual double area() const {return side*side;}              protected:  double side;};class Rectangle:public Shape{public: Rectangle(double w,double h):width(w),height(h){}               virtual double area() const {return width*height;}               protected:  double width,height;                                           };class Trapezoid:public Shape{public:  Trapezoid(double t,double b,double h):top(t),bottom(t),height(h){}   virtual double area() const {return 0.5*(top+bottom)*height;}      protected:  double top,bottom,height;                                        };class Triangle:public Shape{public:  Triangle(double w,double h):width(w),height(h){}                  virtual double area()const {return 0.5*width*height;}           protected:  double width,height;                                         };int main(){ Circle circle(1);                                           Square square(2);                                               Rectangle rectangle(3,4);                                     Trapezoid trapezoid(2,4,3);                                 Triangle triangle(4,5);                                       Shape *pt[5]={&circle,&square,&rectangle,&trapezoid,&triangle};                                                 double areas=0.0;                                      for(int i=0;i<5;i++)  {areas=areas+pt[i]->area();} cout<<"总面积为："<<areas<<endl; return 0;}