The following code it taken from msdn library but it is failing to compile.
the following code has a header where all the variables used here are stored in header App.h.
please help me with this, i cannot really go further without this problem resolved.

The following lines are giving trouble:

Code:
DialogBox(pApp->getInstance(), MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, pApp->About);
error: 'App::About': function call missing argument list; use '&App::About' to create a pointer to member

Code:
wcex.lpfnWndProc	= &App::WndProc;
error: '=' : cannot convert from 'LRESULT (__stdcall App::* )(HWND,UINT,WPARAM,LPARAM)' to 'WNDPROC'
There is no context in which this conversion is possible
(Removing &did not help)


Here is the complete code:


Code:
#include "stdafx.h"
#include "App.h"


App::App(void)
{
}


App::~App(void)
{
}


//Initializing variables
BOOL App::Init(HINSTANCE hInstance, int cmd)
{
   

   hInst = hInstance; // Store instance handle in our global variable
	
   // Initialize global strings
	LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
	LoadString(hInstance, IDC_FIRSTPAINT, szWindowClass, MAX_LOADSTRING);
	MyRegisterClass(hInstance);

	// Perform application initialization:
	if (!InitInstance (cmd))
	{
		return FALSE;
	}
	return true;
}

//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL App::InitInstance(int nCmdShow)
{
	HWND hWnd;
   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
	   CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInst, this);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}


//Function to run the message loop for the class

int App::RunMessageLoop()
{
	MSG msg;
	HACCEL hAccelTable;

	
	hAccelTable = LoadAccelerators(hInst, MAKEINTRESOURCE(IDC_FIRSTPAINT));

	// Main message loop:
	while (GetMessage(&msg, NULL, 0, 0))
	{
		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
		{
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
	}

	return (int) msg.wParam;
}


//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
ATOM App::MyRegisterClass(HINSTANCE hInstance)
{
	WNDCLASSEX wcex;

	wcex.cbSize = sizeof(WNDCLASSEX);

	wcex.style			= CS_HREDRAW | CS_VREDRAW;
	wcex.lpfnWndProc	= &App::WndProc;
	wcex.cbClsExtra		= 0;
	wcex.cbWndExtra		= 0;
	wcex.hInstance		= hInst;
	wcex.hIcon			= LoadIcon(hInst, MAKEINTRESOURCE(IDI_FIRSTPAINT));
	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
	wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1);
	wcex.lpszMenuName	= MAKEINTRESOURCE(IDC_FIRSTPAINT);
	wcex.lpszClassName	= szWindowClass;
	wcex.hIconSm		= LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

	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 App::WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	App* pApp;



    if (message == WM_CREATE)
    {
        LPCREATESTRUCT pcs = (LPCREATESTRUCT)lParam;
        pApp = (App *)pcs->lpCreateParams;
        ::SetWindowLongPtrW(hWnd,GWLP_USERDATA,PtrToUlong(pApp));

        return TRUE;
    }

    else

    {
        pApp = reinterpret_cast<App *>(static_cast<LONG_PTR>(::GetWindowLongPtrW(hWnd,GWLP_USERDATA)));

	 if (!pApp)
           return DefWindowProc(hWnd, message, wParam, lParam);


	int wmId, wmEvent;
	PAINTSTRUCT ps;
	HDC hdc;

	switch (message)
	{
	case WM_COMMAND:
		wmId    = LOWORD(wParam);
		wmEvent = HIWORD(wParam);
		// Parse the menu selections:
		switch (wmId)
		{
		case IDM_ABOUT:
			DialogBox(pApp->getInstance(), MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, pApp->About);
			break;
		case IDM_EXIT:
			DestroyWindow(hWnd);
			break;
		default:
			return DefWindowProc(hWnd, message, wParam, lParam);
		}
		break;
	case WM_PAINT:
		hdc = BeginPaint(hWnd, &ps);
		// TODO: Add any drawing code here...
		EndPaint(hWnd, &ps);
		break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
	return 0;
}
}


// Message handler for about box.
INT_PTR CALLBACK App::About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
	UNREFERENCED_PARAMETER(lParam);
	switch (message)
	{
	case WM_INITDIALOG:
		return (INT_PTR)TRUE;

	case WM_COMMAND:
		if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
		{
			EndDialog(hDlg, LOWORD(wParam));
			return (INT_PTR)TRUE;
		}
		break;
	}
	return (INT_PTR)FALSE;