Help with error C2504

[kostis]

Hello guys,
I am getting a compile error: "...\polygon.h(13): error C2504: 'node' : base class undefined"

#ifndef _NODE_H_
#define _NODE_H_
#include <iostream>
using namespace std;

class node
{
public:
node();
virtual ~node();
//
virtual void draw()=0;
};

#endif

---------------------

#ifndef _POLYGON_H_
#define _POLYGON_H_
#include <iostream>
#include <vector>
using namespace std;

struct Vec{
float x;
float y;
float z;
};

class polygon : public node { //derived class(from base class)
private:
float vertices;
float red,green,blue;
vector <Vec> points;
float xi,yi,zi;
public:
polygon();
~polygon();
void draw();

polygon(const polygon&);
friend istream& operator>>(istream& in, polygon& d);
//friend istream& operator >>(istream& in,shape& color,shape& ;
};

#endif

---------------------------------

#include <fstream>
#include "polygon.h"
using namespace std;

polygon :: polygon()
{

}

istream& operator>>(istream& in, polygon& d)
{
in >> d.red >> d.blue >> d.green;
in >> d.vertices;
Vec t;
for (int i=0;i<d.vertices;i++){
in >> t.x >> t.y >> t.z;
d.points.push_back(t);
}
return in;
}

---------------------------------


I have searched for it, but I was confused and I couldn't find what was wrong.

Please help me out...

Thanks,
Kostis

[hamsterman]

You don't include node.h in polygon.h, so the latter has no knowledge of the former.

[kostis]

After including the node.h into polygon.h I am getting some new errors:

polygon.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall node::~node(void)" (??1node@@UAE@XZ) referenced in function __unwindfunclet$??0polygon@@QAE@XZ$0
1>polygon.obj : error LNK2019: unresolved external symbol "public: __thiscall node::node(void)" (??0node@@QAE@XZ) referenced in function "public: __thiscall polygon::polygon(void)" (??0polygon@@QAE@XZ)
1>polygon.obj : error LNK2001: unresolved external symbol "public: virtual void __thiscall polygon::draw(void)" (?draw@polygon@@UAEXXZ)
1>polygon.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall polygon::~polygon(void)" (??1polygon@@UAE@XZ) referenced in function "public: virtual void * __thiscall polygon::`scalar deleting destructor'(unsigned int)" (??_Gpolygon@@UAEPAXI@Z)