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;
}