c++ - Undefined reference to vtable while implementing virtual functions

I try to implement examples of "C++ An Introduction To
Programming" by Jesse Liberty and Tim Keogh but on implementing pure virtual functions
is compiling but not building. It is giving the error : undefined reference to 'vtable
for circle'

I have tried substituting the
variable itsRadius for a virtual function
GetItsRadius to see if it would work but it started giving me
the same errors in the switch statement but for Rectangle and
Square and also the same error as before for
circle.

Here
is the code:

#include
            

using namespace std;

enum
            BOOL { FALSE, TRUE };

class Shape
{


            public:
 Shape(){}
 ~Shape(){}
 virtual long GetArea() =
            0; // error
 virtual long GetPerim()= 0;
 virtual void Draw() =
            0;
 private:
};

void
            Shape::Draw()

{
 cout << "Abstract drawing
            mechanism!\n";
}

class Circle : public
            Shape
{
 public:
 Circle(int
            radius):itsRadius(radius){}
 ~Circle(){}
 long GetArea() { return 3
            * itsRadius * itsRadius; }

 long GetPerim() { return 9 * itsRadius;
            }
 void Draw();
 private:
 int itsRadius;
 int
            itsCircumference;
};

class Rectangle : public
            Shape
{
 public:

 Rectangle(int len, int
            width):
 itsLength(len), itsWidth(width){}

            ~Rectangle(){}
 long GetArea() { return itsLength * itsWidth; }

            long GetPerim() { return 2*itsLength + 2*itsWidth; }
 virtual int GetLength()
            { itsLength; }
 virtual int GetWidth() { itsWidth; }
 void
            Draw();
 private:
 int itsWidth;

 int
            itsLength;
};

void
            Rectangle::Draw()
{
 for (int i = 0; i
            {
 for (int j = 0; j cout << "x
            ";


 cout << "\n";
 }

            Shape::Draw();
}

class Square : public
            Rectangle
{
 public:
 Square(int len);

            Square(int len, int width);

 ~Square(){}
 long GetPerim()
            {return 4 * GetLength();}
};

Square::Square(int
            len):
 Rectangle(len,len)
{}

Square::Square(int
            len, int width):
 Rectangle(len,width)

{
 if
            (GetLength() != GetWidth())
 cout << "Error, not a square... a
            Rectangle??\n";
}

void startof()
{

            int choice;
 BOOL fQuit = FALSE;
 Shape *
            sp;


 while (1)
 {
 cout <<
            "(1)Circle (2)Rectangle (3)Square (0)Quit: \n";
 cin >>
            choice;

 switch (choice)
 {
 case 1: sp = new
            Circle(5);
 break;

 case 2: sp = new
            Rectangle(4,6);
 break;
 case 3: sp = new Square (5);

            break;
 default: fQuit = TRUE;
 break;
 }
 if
            (fQuit)
 break;


 sp->Draw();

            cout << "\n";
 }
}


int
            main()
{

            startof();
}