#include <iostream>
using namespace std;
class shape
{public:
virtual float area() const {return 0.0;}
virtual float volume() const {return 0.0;}
virtual void shapename() const =0;
};

class point:public shape
{public:
point(float,float);
void setpoint(float,float);
float getX()const {return x;}
float getY()const {return y;}
virtual void shapename() const{cout<<"point:";}
friend ostream & operator << (ostream &,const 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,const point &p)
{
output<<"["<<p.x<<","<<p.y<<"]";
return output;
}
class circle:public point
{public:
circle(float,float,float);
void setRadius(float);
float getradius()const;
virtual float area() const;
virtual void shapename()const {cout<<"circle:";}
friend ostream&operator<<(ostream &,const circle &);
protected:
float radius;
};
circle::circle(float a,float b,float r):point(a,b),radius(r){}
void circle::setRadius(float r){radius=r;}
float circle::getRadius()const{return radius;}
float circle::area()const {return 3.14*radius*radius;}

ostream&operator<<(ostream &output,const circle &c)
{output<<"["<<c.x<<","<<c.y<<"],r="<<c.radius;
return output;
}
class cylinder:public circle
{public :
cylinder(float x,float y,float r,float h);
void setheight(float);
virtual float area()const;
virtual float volume()const;;
virtual void shapename()const{cout<<"cylinder:";}
friend ostream&operator<<(ostream &,const cylinder&);
protected:
float height;
};
cylinder::cylinder(float a,float b,float r,float h):circle(a,b,r),height(h){}
void cylinder::getheight(flaot h){height=h;}
float cylinder::area()const
{return 2*circle::area()+2*3.14*radius*height;}
float cylinder::volume()const
{return circle::area()*height;}
ostream&operator<<(ostream &output,const cylinder &cy)
{output<<"["<<cy.x<<","<<cy.y<<"],r="<<cy.radius<<",h="<<cy.height;
return output;
}
int main()
{point point(3.2,4.3);
circle circle(2.4,1.2,5.6);
cylinder cylinder(3.2,4.4,5.4,4.6);
point.shapename();
cout<<point<<endl;
circle.shapename();
cout<<circle<<endl;
cylinder.shapename();
cout<<cylinder<<endl<<endl;
shape *pt;
pt=&point;
pt->shapename();
cout<<"x="<<point.getX()<<",y="<<point.getY()<<"\area="<<pt->area()
<<"\nvolume="<<pt->volume()<<"\n\n";
pt=&circle;
pt->shapename();
cout<<"x="<<circle.getX()<<",y="<<circle.getY()<<"\narea="<<pt->area()
<<"\nvolume="<<pt->volume()<<"\n\n";
pt=&cylinder;
pt->shapename();
cout<<"x="<<circle.getX()<<",y="<<circle.getY()<<"\narea="<<pt->area()
<<"\nvolume="<<pt->volume()<<"\n\n";
return 0;
}
找了半天不知道错在哪啊 我按书上打的啊
大家帮我看看

呵呵，你可真喜欢偷懒，以后调试吧。

程序代码：

#include <iostream>
using namespace std;
class shape
{
public:
    virtual float area() const {return 0.0;}
    virtual float volume() const {return 0.0;}
    virtual void  shapename() const =0;
};

class point:public shape
{
public:
    point(float,float);
    void setpoint(float,float);
    float getX()const {return x;}
    float getY()const {return y;}
    virtual void shapename() const{cout<<\"point:\";}
    friend ostream&operator<<(ostream &output,const point &p)
    {
        output<<\"[\"<<p.x<<\",\"<<p.y<<\"]\";
        return output;
    }
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;
}

class circle:public point
{
public:
    circle(float,float,float);
    void setRadius(float);
    float getRadius()const;
    virtual float area() const;
    virtual void shapename()const {cout<<\"circle:\";}
    friend ostream&operator<<(ostream &output,const circle &c)
    {
        output<<\"[\"<<c.x<<\",\"<<c.y<<\"],r=\"<<c.radius;
        return output;
    }
protected:
    float radius;
};
circle::circle(float a,float b,float r)
: point(a,b)
, radius(r)
{
    
}
void circle::setRadius(float r)
{
    radius=r;
}
float circle::getRadius()const
{
    return radius;
}
float circle::area()const
{
    return 3.14*radius*radius;
}

class cylinder:public circle
{
public :
    cylinder(float x,float y,float r,float h);
    void setheight(float);
    virtual float area()const;
    virtual float volume()const;;
    virtual void shapename()const{cout<<\"cylinder:\";}
    friend ostream&operator<<(ostream &output,const cylinder &cy)
    {
        output<<\"[\"<<cy.x<<\",\"<<cy.y<<\"],r=\"<<cy.radius<<\",h=\"<<cy.height;
        return output;
    }
protected:
    float height;
};
cylinder::cylinder(float a,float b,float r,float h)
: circle(a,b,r)
, height(h)
{
    
}
void cylinder::setheight(float h)
{
    height=h;
}
float cylinder::area()const
{
    return 2*circle::area()+2*3.14*radius*height;
}
float cylinder::volume()const
{
    return circle::area()*height;
}
int main()
{
    point point(3.2f,4.3f);
    circle circle(2.4f,1.2f,5.6f);
    cylinder cylinder(3.2f,4.4f,5.4f,4.6f);
    point.shapename();
    cout<<point<<endl;
    circle.shapename();
    cout<<circle<<endl;
    cylinder.shapename();
    cout<<cylinder<<endl<<endl;
    shape *pt;
    pt=&point;
    pt->shapename();
    cout<<\"x=\"<<point.getX()<<\",y=\"<<point.getY()<<\"\area=\"<<pt->area()
        <<\"\nvolume=\"<<pt->volume()<<\"\n\n\";
    pt=&circle;
    pt->shapename();
    cout<<\"x=\"<<circle.getX()<<\",y=\"<<circle.getY()<<\"\narea=\"<<pt->area()
        <<\"\nvolume=\"<<pt->volume()<<\"\n\n\";
    pt=&cylinder;
    pt->shapename();
    cout<<\"x=\"<<circle.getX()<<\",y=\"<<circle.getY()<<\"\narea=\"<<pt->area()
        <<\"\nvolume=\"<<pt->volume()<<\"\n\n\";
    return 0;
}