C++第六章习题第一题

1.#include <iostream.h>

class Point

{

public:

 Point(float x=0,float y=0);

 void setPoint(float,float);

 float getX() const

 {return x;}

 float getY() const

 {return y;}

 friend ostream & operator<<(ostream &output,Point &);

protected:

 float x,y;

};

Point::Point(float a,float b)

{

 x=a;y=b;

}

void Point::setPoint(float a,float b)

{

 x=a;y=b;

}

ostream & operator<<(ostream &output,Point &p)

{

 output<<"["<<p.x<<","<<p.y<<"]"<<endl;

 return output;

}

class Circle:public Point

{

public:

 Circle(float x,float y,float r):Point(x,y),radius(r){}

 void setRadius(float r)

 {radius=r;}

 float getRadius() const

 {return radius;}

 double area() const

 {

  return 3.1415*radius*radius;

 }

 friend ostream & operator<<(ostream &output,Circle &);

protected:

 float radius;

};

ostream & operator<<(ostream &output,Circle &c)

{

 output<<"Center =["<<c.x<<","<<c.y<<"],r= "<<c.radius<<",area="<<c.area()<<endl;

 return output;

}

class Cylinder:public Circle

{

public:

 Cylinder(float x,float y,float r,float h):Circle(x,y,r),height(h){}

 void setHeight(float h)

 {height=h;}

 float getHeight() const

 {return height;}

 double area() const

 {

  return 2*Circle::area()+2*3.1415*radius*height;

 }

 double volume() const

 {

     return 3.1415*radius*radius*height;

 }

 friend ostream & operator<<(ostream &output,Cylinder &);

protected:

 float height;

};

ostream & operator<<(ostream &output,Cylinder &cy)

{

 output<<"Center=["<<cy.x<<cy.y<<"],r="<<cy.radius<<",h="<<cy.height<<"\narea="<<cy.area()<<",volume="<<cy.volume()<<endl;

 return output;

}

int main()

{

 Cylinder cy1(3.5,6.4,5.2,10);

 cout<<"original 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;

}