#include <windows.h>
#include <d3d8.h>
#include <iostream>
using namespace std;


LRESULT CALLBACK MainMsg(HWND, UINT, LPARAM, WPARAM);
bool RegisterWinClass(HINSTANCE, WNDPROC, LPSTR);
bool CreateWin(HWND&, HINSTANCE, LPSTR, LPSTR);
WPARAM MainLoop();
bool Inti(HWND&);
bool DestroyWin();
void ClearUp();
void Render();


HWND g_hWnd = NULL;
HDC g_hDc = NULL;


LPDIRECT3D8 g_pD3d = NULL;
LPDIRECT3DDEVICE8 g_pD3ddevice = NULL;



int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
				   LPSTR lpstrCmdLine, int iCmdShow)
{
	if(!RegisterWinClass(hInstance, MainMsg, "DXTest"))
	{
		return -1;
	}
	
	CreateWin(g_hWnd, hInstance, "DXTest", "Direct X Test");
    
	Inti(g_hWnd);

	ShowWindow(g_hWnd, SW_SHOWDEFAULT);
	UpdateWindow(g_hWnd);

	return (int)MainLoop();
}


LRESULT CALLBACK MainMsg(HWND hWnd, UINT uiMsg, LPARAM lParam, 
						 WPARAM wParam)
{
	switch(uiMsg)
	{
		case WM_PAINT:
			{
				Render();
				ValidateRect(g_hWnd, NULL);
				break;
            }
		case WM_CREATE:
			{
				break;
			}
		case WM_CLOSE:
			{
				PostQuitMessage(0);
				break;
			}
		case WM_DESTROY:
			{
				break;
			}
		default:
			{
				break;
			}
	}

	return DefWindowProc(hWnd, uiMsg, lParam, wParam);
}


bool RegisterWinClass(HINSTANCE hInstance, WNDPROC wndProc, LPSTR className)
{
	WNDCLASSEX wcx;

	wcx.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
	wcx.cbSize = sizeof(WNDCLASSEX);
	wcx.hInstance = hInstance;
	wcx.lpfnWndProc = wndProc;
	wcx.lpszClassName = className;

	wcx.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wcx.hCursor = LoadCursor(NULL, IDC_ARROW);
	wcx.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wcx.hIconSm = LoadIcon(NULL, IDI_WINLOGO);

	wcx.cbClsExtra = NULL;
	wcx.cbWndExtra = NULL;
	wcx.lpszMenuName = NULL;

	if(!RegisterClassEx(&wcx))
	{
		return false;
	}

	return true;
}


bool CreateWin(HWND &hWnd, HINSTANCE hInstance, LPSTR className, 
			   LPSTR winCaption)
{
	hWnd = CreateWindowEx(NULL,
						  className,
						  winCaption,
						  WS_OVERLAPPEDWINDOW,
						  0,
						  0,
						  CW_USEDEFAULT,
						  CW_USEDEFAULT,
						  NULL,
						  NULL,
						  hInstance,
						  NULL);

	if(!hWnd)
	{
		return false;
	}

	return true;
}


WPARAM MainLoop()
{
	MSG msg;
	bool done = false;

	while(!done)
	{
		if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
		{
			if(msg.message == WM_QUIT)
			{
				done = true;
				break;
			}

			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
		else
		{

		}

	}
	
	ClearUp();

	return msg.wParam;
}

Error:
c:\Dev\WinDXTest\main.cpp(25): error C2664: 'RegisterWinClass' : cannot convert parameter 2 from 'LRESULT (HWND,UINT,LPARAM,WPARAM)' to 'WNDPROC'
 

#include <d3d8.h>#include <iostream>using namespace std;bool RegisterWinClass(HINSTANCE, WNDPROC, LPSTR);bool CreateWin(HWND&, HINSTANCE, LPSTR, LPSTR);LRESULT CALLBACK MainMsg(HWND, UINT, WPARAM, LPARAM);WPARAM MainLoop();bool Inti(HWND&);bool DestroyWin();void ClearUp();void Render();HWND g_hWnd = NULL;HDC g_hDc = NULL;LPDIRECT3D8 g_pD3d = NULL;LPDIRECT3DDEVICE8 g_pD3ddevice = NULL;int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,				   LPSTR lpstrCmdLine, int iCmdShow){	if(!RegisterWinClass(hInstance, MainMsg, "DXTest"))	{		return -1;	}	        //The Error come from CreateWin() funtion...	if(!CreateWin(g_hWnd, hInstance, "DXTest", "DirectXTest"))	{		return -2;	}    	if(!Inti(g_hWnd))	{		return -3;	}	ShowWindow(g_hWnd, SW_SHOWDEFAULT);	UpdateWindow(g_hWnd);			return (int)MainLoop();}bool RegisterWinClass(HINSTANCE hInstance, WNDPROC wndProc, 					  LPSTR className){	WNDCLASSEX wcx;	wcx.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;	wcx.cbSize = sizeof(WNDCLASSEX);	wcx.hInstance = hInstance;	wcx.lpfnWndProc = wndProc;	wcx.lpszClassName = className;	wcx.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);	wcx.hCursor = LoadCursor(NULL, IDC_ARROW);	wcx.hIcon = LoadIcon(NULL, IDI_APPLICATION);	wcx.hIconSm = LoadIcon(NULL, IDI_WINLOGO);	wcx.cbClsExtra = NULL;	wcx.cbWndExtra = NULL;	wcx.lpszMenuName = NULL;	if(!RegisterClassEx(&wcx))	{		return false;	}	return true;}bool CreateWin(HWND &hWnd, HINSTANCE hInstance, LPSTR className, 			   LPSTR winCaption){	hWnd = CreateWindowEx(NULL,						  className,						  winCaption,						  WS_OVERLAPPEDWINDOW,						  0,						  0,						  CW_USEDEFAULT,						  CW_USEDEFAULT,						  NULL,						  NULL,						  hInstance,						  NULL);	if(!hWnd)	{		return false;	}	return true;}

The program ''[1492] WinDXTest.exe: Native'' has exited with code -2 (0xfffffffe).