Error identifier "hwnd" undifined i look up to google but nothing found can somebody explain me how to fix it

#include <windows.h>
#include <stdlib.h>
#include <string.h>
#include <tchar.h>

// Global variables

// The main window class name.
static TCHAR szWindowClass[] = _T("win32app");

// The string that appears in the application's title bar.
static TCHAR szTitle[] = _T("Win32 Guided Tour Application");

HINSTANCE hInst;

// Forward declarations of functions included in this code module:
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance,
     HINSTANCE hPrevInstance,
     LPSTR lpCmdLine,
     int nCmdShow)
{
    WNDCLASSEX wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style    = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra  = 0;
    wcex.cbWndExtra  = 0;
    wcex.hInstance  = hInstance;
    wcex.hIcon    = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
    wcex.hCursor  = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;
    wcex.lpszClassName  = szWindowClass;
    wcex.hIconSm  = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_APPLICATION));

    if (!RegisterClassEx(&wcex))
    {
  MessageBox(NULL,
    _T("Call to RegisterClassEx failed!"),
    _T("Win32 Guided Tour"),
    NULL);

  return 1;
    }

    hInst = hInstance; // Store instance handle in our global variable

    // The parameters to CreateWindow explained:
    // szWindowClass: the name of the application
    // szTitle: the text that appears in the title bar
    // WS_OVERLAPPEDWINDOW: the type of window to create
    // CW_USEDEFAULT, CW_USEDEFAULT: initial position (x, y)
    // 500, 100: initial size (width, length)
    // NULL: the parent of this window
    // NULL: this application does not have a menu bar
    // hInstance: the first parameter from WinMain
    // NULL: not used in this application
    HWND hWnd = CreateWindow(
  szWindowClass,
  szTitle,
  WS_OVERLAPPEDWINDOW,
  CW_USEDEFAULT, CW_USEDEFAULT,
  500, 500,
  NULL,
  NULL,
  hInstance,
  NULL
    );

    if (!hWnd)
    {
  MessageBox(NULL,
    _T("Call to CreateWindow failed!"),
    _T("Win32 Guided Tour"),
    NULL);

  return 1;
    }

    // The parameters to ShowWindow explained:
    // hWnd: the value returned from CreateWindow
    // nCmdShow: the fourth parameter from WinMain
    ShowWindow(hWnd,
  nCmdShow);
    UpdateWindow(hWnd);

    // Main message loop:
    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0))
    {
  TranslateMessage(&msg);
  DispatchMessage(&msg);
    }

    return (int) msg.wParam;
}

//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  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)
{

    switch (message)
    {
    case WM_CREATE:
            CreateWindow(TEXT("button"), TEXT("Hello world"),
                WS_VISIBLE | WS_CHILD,
                10, 10, 80, 25,
                hwnd,(HWMENU) 1, NULL, NULL
                );
  // Here your application is laid out.
  // For this introduction, we just print out "Hello, World!"
  // in the top left corner.
  // End application-specific layout section.

  break;
    case WM_DESTROY:
  PostQuitMessage(0);
  break;
    default:
  return DefWindowProc(hWnd, message, wParam, lParam);
  break;
    }

    return 0;
}