求大神帮忙看看程序那里出错了

#include
using namespace std;
class ClsShape
{
public:
    virtual float area() const {return 0.0;}
    virtual float perimeter() const {return 0.0;}
    virtual float volume() const = 0;
};
class ClsRect:public ClsShape
{
public:
    ClsRect(float l , float w):length(l),width(w){};
    float area() const;
    float perimeter() const;
protected:
    float length;
    float width;
};
float ClsRect::area() const
{
    return length * width ;
}
float ClsRect::perimeter() const
{
    return 2 * (length + width);
}
class ClsCub : public ClsRect
{
public:
    ClsCub(float h, float l, float w) : ClsRect(l,w)
    {
        height = h;
    }
    float area() const;
    float perimeter() const;
    float volume() const;
private:
    float height;
};
float ClsCub::area() const
{
    return 2 * (length * width + width * height + length * height);
}
float ClsCub::perimeter() const
{
    return 4 * (length + width + height);
}
float ClsCub::volume() const
{
    return length * width * height;
}
int main()
{
    //...
    return 0;
}