一个C++小程序，请大家帮帮忙哈。。。谢谢
怎么将私有数据传到派生类，让派生类函数成员实用。
#include<iostream.h>
const double PI=3.1415;
class Shape
{
public:
Shape(int l,int w,int r):length(r),width(w),radius(r){}
virtual void getArea()=0;
virtual void getPerim()=0;
virtual int getl()=0;
virtual int getw()=0;
virtual int getr()=0;
private:
int length,width,radius;
};
class Rectangle:public Shape
{
public:
Rectangle(int i,int j,int k):Shape(i,j,k){}
void getArea();
void getPerim();
int getl(){return length;}
int getw(){return width;}
int getr(){return radius;}
};
void Rectangle::getArea()
{
int area;
area=getl()*getw();
cout<<"Rectangle area is:"<<area<<endl;
}
void Rectangle::getPerim()
{
int perim;
perim=getl()+getl()+getw()+getw();
cout<<"Recatanle perim is:"<<perim<<endl;
}
class Circle:public Shape
{
public:
Circle(int i,int j,int k):Shape(i,j,k){}
void getArea();
void getPerim();
int getl(){return length;}
int getw(){return width;}
int getr(){return radius;}
};
void Circle::getArea()
{
double area;
area=PI*getr()*getr();
cout<<"Circle area is:"<<area<<endl;
}
void Circle::getPerim()
{
double perim;
perim=2*PI*getr();
cout<<"Circle perim is:"<<perim<<endl;
}
void fun(Shape *ptr)
{
ptr->getArea();
ptr->getPerim();
}
int main()
{
int x,y,z;
cout<<"please input length and width:";cin>>x>>y;
cout<<"please input radius:";cin>>z;
Rectangle R(x,y,z);
Circle C(x,y,z);
fun(&R);
fun(&C);
return 0;
}