Question

error C2504: 'Circle' : base class undefined

工程建的是win32 console application
#include "iostream.h"
const double PI=3.14;
class Circle
{ double radius;
public: Circle(double r)
{radius=r;
double CircleArea(void){return PI*raidus*raidus;}
};
class Rectangle
{ double length,width;
public: Rectangle(double x,double y){length=x,width=y;}
double RecArea(void){return length*width;}
};

class Graph:public Circle,public Rectangle //在这提示error C2504: 'Circle' : base class undefined
{ public: Graph(double r,double x,double y):Circle(r).Rectangle(x,y){}
void ShowArea(void)
{double TotalArea;
TotalArea=CircleArea()+RecArea();
cout<<"the Area of Graph is"<<TotalArea<<endl;
}
};

void main()
{ double x,y,r;
cout<<"r=";cin>>r;
cout<<"x=",cin>>y;
cout<<"y=";cin>>y;
Graph g(r,x,y);
g.ShowArea();
}

Answer 1

#include "iostream.h"
const double PI=3.14;

class Circle
{ double radius;
public: Circle(double r)
{radius=r;}
double CircleArea(void){return PI*radius*radius;}
};
class Rectangle
{ double length,width;
public: Rectangle(double x,double y){length=x,width=y;}
double RecArea(void){return length*width;}
};

class Graph:public Circle,public Rectangle
{ public: Graph(double r,double x,double y):Circle(r),Rectangle(x,y){}
void ShowArea(void)
{double TotalArea;
TotalArea=CircleArea()+RecArea();
cout<<"the Area of Graph is"<<TotalArea<<endl;
}
};

void main()
{ double x,y,r;
cout<<"r=";cin>>r;
cout<<"x=",cin>>x;
cout<<"y=";cin>>y;
Graph g(r,x,y);
g.ShowArea();
}