Linker Error: Abstract base and 2 derived classes in singleton pattern

Hello all,

This is my first message to the group.

I have a question where i derive 2 child classes which are of
singleton pattern from an abstract base class.

Code:

//********************************************** test1.h
*******************************//
#include <iostream>
using namespace std;

class CPolygon {
 protected:
   int width, height;
 public:
   CPolygon(){};
   virtual ~CPolygon(){};
   void set_values (int a, int b)
     { width=a; height=b; }
   virtual int area (void) = 0;
   void printarea (void)
     { cout << this->area() << endl; }

 };

class CRectangle: public CPolygon {
 public:
   int area (void)
     { return (width * height); }
   static CRectangle* GetInstance()
     { if (!rectanglePtr) rectanglePtr = new CRectangle(); return
rectanglePtr; }
 ~CRectangle();
 protected:
       CRectangle();
       static CRectangle* rectanglePtr;
       CRectangle(CRectangle const&){};
       CRectangle& operator=(CRectangle&){};
 };

CRectangle* CRectangle::rectanglePtr = NULL;

class CTriangle: public CPolygon {
 public:
   int area (void)
     { return (width * height / 2); }

   static CTriangle* GetInstance()
     { if (!trianglePtr) trianglePtr = new CTriangle(); return
trianglePtr; }
 ~CTriangle();
 protected:
   CTriangle();
   static CTriangle* trianglePtr;
   CTriangle(CTriangle const&){}
   CTriangle& operator=(CTriangle&){};
 };

CTriangle* CTriangle::trianglePtr = NULL;

//******************************************* test1.cpp
*******************//
#include "test1.h"

int main (void)
{
 CPolygon *ppoly1 = CRectangle::GetInstance();
 CTriangle *ppoly2 = CTriangle::GetInstance();
 ppoly1->set_values (4,5);
 ppoly2->set_values (4,5);
 ppoly1->printarea();
 ppoly2->printarea();
 delete ppoly1;
 delete ppoly2;
 return 0;
}

so when i compile and link them

this is the error am looking at ....

[root@Krea-TV-DT1 IMGAdapter]# g++ -o test1.out test1.o
test1.o: In function `CRectangle::GetInstance()':
test1.cpp:
(.text._ZN10CRectangle11GetInstanceEv[CRectangle::GetInstance()]+0xa):
undefined reference to `CRectangle::rectanglePtr'
test1.cpp:
(.text._ZN10CRectangle11GetInstanceEv[CRectangle::GetInstance()]
+0x26): undefined reference to `CRectangle::CRectangle()'
test1.cpp:
(.text._ZN10CRectangle11GetInstanceEv[CRectangle::GetInstance()]
+0x47): undefined reference to `CRectangle::rectanglePtr'
test1.cpp:
(.text._ZN10CRectangle11GetInstanceEv[CRectangle::GetInstance()]
+0x4c): undefined reference to `CRectangle::rectanglePtr'
test1.o: In function `CTriangle::GetInstance()':
test1.cpp:
(.text._ZN9CTriangle11GetInstanceEv[CTriangle::GetInstance()]
+0xa): undefined reference to `CTriangle::trianglePtr'
test1.cpp:
(.text._ZN9CTriangle11GetInstanceEv[CTriangle::GetInstance()]
+0x26): undefined reference to `CTriangle::CTriangle()'
test1.cpp:
(.text._ZN9CTriangle11GetInstanceEv[CTriangle::GetInstance()]
+0x47): undefined reference to `CTriangle::trianglePtr'
test1.cpp:
(.text._ZN9CTriangle11GetInstanceEv[CTriangle::GetInstance()]
+0x4c): undefined reference to `CTriangle::trianglePtr'
collect2: ld returned 1 exit status

Please let me know as to what mistake am i doing .

Thanks,

Vinesh.S