#include<iostream> using namespace std; class CPoint { private: double x,y; public : CPoint (double i,double j); double Getx(); double Gety(); double Setpoint(double i,double j); }; class CShape { public: CPoint point; virtual double Area() { return 0.0; } }; class CCircle:public CShape { public: float r; CCircle(CPoint p1,float r=2):r(r){} double Area() { return 3.14*r*r; } }; class CRect:public CShape { public: double x; double y; CRect(CPoint p1,double x=2,double y=1):x(x),y(y) {} double Area() { return x*y; } }; class CEll:public CShape { double x; double y; CEll(CPoint p1,double x=2,double y=1); double Area() { return 3.14*x*y; } }; int main() { return 0; }有什么问题？怎么改正？

这段代码存在一个问题，即CEll类的构造函数是私有的，无法在main函数中创建CEll对象。需要将CEll类的构造函数改为公有的。

修改后的代码如下：

#include<iostream> 
using namespace std; 

class CPoint { 
private:     
    double x,y; 
public :     
    CPoint (double i,double j);     
    double Getx();     
    double Gety();     
    double Setpoint(double i,double j); 
}; 

class CShape { 
public:     
    CPoint point;     
    virtual double Area()     
    {         
        return 0.0;     
    } 
}; 

class CCircle:public CShape { 
public:     
    float r;     
    CCircle(CPoint p1,float r=2):r(r){}     
    double Area()     
    {         
        return 3.14*r*r;     
    } 
}; 

class CRect:public CShape { 
public:     
    double x;     
    double y;     
    CRect(CPoint p1,double x=2,double y=1):x(x),y(y) {}     
    double Area()     
    {         
        return x*y;     
    } 
}; 

class CEll:public CShape {     
public:
    double x;     
    double y;     
    CEll(CPoint p1,double x=2,double y=1):x(x),y(y){}     
    double Area()     
    {         
        return 3.14*x*y;     
    } 
}; 

int main() {     
    return 0; 
}