Ошибки Линкера

//stdafx.cpp
#include "stdafx.h"
struct pos
{
    UINT x, y, size;
    pos(){}
    pos(UINT _x, UINT _y, UINT _s) : x(_x), y(_y), size(_s){}
};
class UNIT
{
protected:
    UINT value;
    bool color;
    pos position;
public:
    UNIT(){}
    UNIT(UINT val, bool col, UINT _x, UINT _y) : value(val), color(col) { position.x = _x; position.y = _y; }
 
    pos get_pos()
    {
        return position;
    }
 
    virtual pos* generate_steps() const;
    virtual void go2(UINT _x, UINT _y);
};
 
struct PAWN : public UNIT
{
    PAWN() : UNIT(2, 0, 0, 0){}
    PAWN(bool _col, UINT _x, UINT _y) : UNIT(2, _col, _x, _y){}
    pos* generate_steps()
    {
        if (color == WHITE)
        if (position.y == 2)
        {
            pos* a = new pos[2];
            a[0] = pos(position.x, 3, 2);
            a[1] = pos(position.x, 4, 2);
            return a;
        }
        else
        {
            pos* a = new pos(position.x, position.y + 1, 1);
            return a;
        }
        else if (position.y == 7)
        {
            pos* a = new pos[2];
            a[0] = pos(position.x, 6, 2);
            a[1] = pos(position.x, 5, 2);
        }
        else
        {
            pos* a = new pos(position.x, position.y - 1, 1);
            return a;
        }
    }
    
};
static UNIT* chessboard[8][8];
void UNIT::go2(UINT _x, UINT _y)
    {
        chessboard[_x][_y] = this;
        delete chessboard[position.x][position.y];
    }
//Win32Project7.cpp
#include "stdafx.h"
#include "stdafx.cpp"
// Global Variables:
HINSTANCE hInst;                                // current instance
TCHAR szTitle[] = "MyWindow";                   // The title bar text
TCHAR szMainWindow[] = "MyWindow";          // the main window class name
// Forward declarations of functions included in this code module:
ATOM MyRegisterClass(HINSTANCE hInstance, LPCSTR, WNDPROC);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
 
int APIENTRY _tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow)
{
    MSG msg;
    HWND hWnd;
    MyRegisterClass(hInstance, szMainWindow, WndProc);
 
    hWnd = CreateWindow(szMainWindow, szTitle, WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);
 
    if (!hWnd)
    {
        return FALSE;
    }
 
    ShowWindow(hWnd, nCmdShow);
 
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
 
    return (int)msg.wParam;
}
 
 
 
//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
ATOM MyRegisterClass(HINSTANCE hInstance, LPCSTR szClassname, WNDPROC Proc)
{
    WNDCLASSEX wcex;
    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = Proc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon(hInstance, IDI_APPLICATION);
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = szClassname;
    wcex.hIconSm = LoadIcon(wcex.hInstance, IDI_APPLICATION);
 
    return RegisterClassEx(&wcex);
}
 
//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND  - process the application menu
//  WM_PAINT    - Paint the main window
//  WM_DESTROY  - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static HWND hWnd2;
    static RECT wnd, cl;
    static int x, y;
 
    switch (message)
    {
    case WM_CREATE:
        chessboard[1][2] = new PAWN(WHITE, 1, 2);
        chessboard[2][2] = new PAWN(WHITE, 2, 2);
        chessboard[3][2] = new PAWN(WHITE, 3, 2);
        chessboard[4][2] = new PAWN(WHITE, 4, 2);
        chessboard[5][2] = new PAWN(WHITE, 5, 2);
        chessboard[6][2] = new PAWN(WHITE, 6, 2);
        chessboard[7][2] = new PAWN(WHITE, 7, 2);
        chessboard[8][2] = new PAWN(WHITE, 8, 2);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}
 
//
// stdafx.h : include file for standard system include files,
// or project specific include files that are used frequently, but
// are changed infrequently
//
#define BLACK 1
#define WHITE 0
 
#pragma once
// Windows Header Files:
#include <windows.h>
#include "resource.h"
 
// C RunTime Header Files
#include <stdlib.h>
#include <malloc.h>
#include <memory.h>
#include <tchar.h>
 
 
// TODO: reference additional headers your program requires here