C++ MFC有进程没有界面

#include <Windows.h>                     //Windows程序需要包含Windows的头文件
#include <stdio.h>

//可以通过MSDN查看回调函数的声明方式
LRESULT CALLBACK WinQinProc(HWND hwnd,
       UINT uMsg,
       WPARAM wParam,
       LPARAM lParam
);




//WinMain.通过查看MSDN找到声明方式
int __stdcall WinMain( HINSTANCE hInstance,
   HINSTANCE hPrevInstance,
   LPSTR lpCmdLine,
   int nCmdShow
)
{
 //设计一个窗口类
 WNDCLASS wndcls;
 wndcls.cbClsExtra = 0;
 wndcls.cbWndExtra = 0;
 wndcls.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);     //白色的刷子
 wndcls.hCursor = LoadCursor(NULL, IDC_CROSS);      //十字形光标。因为标准的，所以第一个参数为NULL
 wndcls.hIcon = LoadIcon(NULL, IDI_APPLICATION);   //窗口上面是应用程序的图标
 wndcls.hInstance = hInstance;
 wndcls.lpfnWndProc = WinQinProc;                             //窗口过程函数。回调函数
 wndcls.lpszClassName = "qinwg";                                //类名
 wndcls.lpszMenuName = NULL;                                   //没有菜单
 wndcls.style = CS_HREDRAW | CS_VREDRAW;          //CS：类的样式---水平重绘、垂直重绘

 //注册窗口
 RegisterClass(&wndcls);

 //创建窗口
 HWND hwnd;
 hwnd = CreateWindow("qinwg", "qinwg's Program",WS_OVERLAPPEDWINDOW,
  50,50,600,400, NULL,NULL,hInstance,NULL);

 //显示窗口
 ShowWindow(hwnd, SW_SHOWNORMAL);
 UpdateWindow(hwnd);

 //消息循环机制
 MSG msg;
 //GetMessage取到WM_QUIT消息时，返回值为0，退出循环
 while (GetMessage(&msg, NULL, NULL, NULL))    //第二个参数为NULL，表示接受所有窗口消息
 {
  TranslateMessage(&msg);
  DispatchMessage(&msg);
 }

 return 0;
}


//窗口过程函数实现过程
LRESULT CALLBACK WinQinProc(HWND hwnd,
       UINT uMsg,
       WPARAM wParam,
       LPARAM lParam
)
{
 HDC hDC;                              //Device Context的句柄
 switch(uMsg)                       //针对不同消息处理过程
 {
 case WM_PAINT:                  //窗口重绘时，触发的消息
  PAINTSTRUCT ps;
  hDC=BeginPaint(hwnd, &ps);              //BeginPaint/EndPaint只能用在WM_PAINT消息中
  TextOut(hDC, 50, 50, "This is first MFC Program!", strlen( "This is first MFC Program!"));
  EndPaint(hwnd, &ps);
  break;
 case WM_CHAR:                 //按下键盘字母键响应消息
  char cArry[20];
  memset(cArry, 0, 20);
  sprintf(cArry, "char is %d", wParam);
  MessageBox(hwnd, cArry, "WM_CHAR", MB_OKCANCEL);
  break;
 case WM_LBUTTONDOWN:
  MessageBox(hwnd, "LeftMouse Click", "WM_LBUTTONDOWN", MB_OKCANCEL);
  hDC = GetDC(hwnd);
  TextOut(hDC, 50, 100, "MFC Program!", strlen( "MFC Program!"));
  ReleaseDC(hwnd,hDC);
  break;
 case WM_CLOSE:
  if (IDOK == MessageBox(hwnd, "是否真的要退出？", "提示", MB_OKCANCEL))
  {
   DestroyWindow(hwnd);                     //销毁窗口，同时发送WM_DESTROY消息
  }
  break;
 case WM_DESTROY:
  PostQuitMessage(0);                            //发送WM_QUIT消息
  break;
 default:
  return DefWindowProc(hwnd,uMsg,wParam,lParam);            //对待不关心的消息，采用默认方式处理
 }

 return 0;
}