Win32代码异常

Question

I am facing a very odd problem. Can any one tell me what is wrong with the following code-:

#include <Windows.h>

LRESULT CALLBACK WindowFunc(HWND, UINT, WPARAM, LPARAM);

char szWinName[]="MyWin";

int WINAPI WinMain(HINSTANCE hThisInst, HINSTANCE hPrevInst,
                   LPSTR lpszArgs, int nWinMode)
{
    HWND hwnd;
    MSG msg;
    WNDCLASSEX wndclass;

    wndclass.cbSize=sizeof(WNDCLASSEX);

    wndclass.hInstance=hThisInst;
    wndclass.lpszClassName=szWinName;
    wndclass.lpfnWndProc=WindowFunc;
    wndclass.style=0;

    wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION)
    wndclass.hIconSm=NULL;
    wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);

    wndclass.lpszMenuName=NULL;
    wndclass.cbClsExtra=0;
    wndclass.cbWndExtra=0;

    wndclass.hbrBackground=(HBRUSH) GetStockObject(LTGRAY_BRUSH);

    if(!RegisterClassEx(&wndclass)) return 0;

    hwnd=CreateWindow(
        szWinName,
        "Hello World",
        WS_OVERLAPPED,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        500,
        500,
        NULL,
        NULL,
        hThisInst,
        NULL
        );

    ShowWindow(hwnd, nWinMode);
    UpdateWindow(hwnd);

    while(GetMessage(&msg, NULL, 0, 0)>0)
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;

}

LRESULT CALLBACK WindowFunc(HWND hwnd, UINT message, WPARAM wparam, 
                            LPARAM lparam)
{
    switch(message){
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        default:
            return DefWindowProc(hwnd,message,wparam,lparam);
    }
    return 0;
}

I am getting the following window-:

As you can see there is no system menu. I do not know why this is happening. But if I replace the above code with the following code it seems to work just fine-:

#include<windows.h>

LRESULT CALLBACK WinProc(HWND,UINT,WPARAM,LPARAM); 

char szWinName[]="Main Window";

int WINAPI WinMain(HINSTANCE thisInst,HINSTANCE prevInst,
                             LPSTR lpCmdArgs, int nMode){

  HWND hwnd;
  MSG msg;
  WNDCLASSEX wndclass;

  wndclass.cbSize=sizeof(WNDCLASSEX);

  wndclass.hInstance=thisInst;
  wndclass.lpszClassName=szWinName;
  wndclass.lpfnWndProc=WinProc;
  wndclass.style=0;

  wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION)
  wndclass.hIconSm=NULL;
  wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);

  wndclass.lpszMenuName=NULL;
  wndclass.cbClsExtra=0;
  wndclass.cbWndExtra=0;

  wndclass.hbrBackground=(HBRUSH)GetStockObject(LTGRAY_BRUSH);

  if(!RegisterClassEx(&wndclass)) return 0;

  hwnd=CreateWindow( szWinName,
                     "Hello World",
                     WS_OVERLAPPEDWINDOW,
                     CW_USEDEFAULT,
                     CW_USEDEFAULT,
                     500,
                     500,
                     NULL,
                     NULL,
                     thisInst,
                     NULL
  );

  ShowWindow(hwnd,nMode);
  UpdateWindow(hwnd);

  while(GetMessage(&msg,NULL,0,0))
  {
    TranslateMessage(&msg);                                  
    DispatchMessage(&msg);  
}
    return msg.wParam;

}

    LRESULT CALLBACK WinProc(HWND hWnd, UINT message,
                              WPARAM wparam, LPARAM lparam){

    switch(message){
                case WM_DESTROY:
                     PostQuitMessage(0);
                     break;
                default:
                return DefWindowProc(hWnd, message, wparam, lparam);
                }
    return 0;
}                    

Please can someone tell me what I doing wrong in the first code segment I have tried everything and not been able to find what is wrong with it. I am using a normal Win32 Project in Visual Studio 2008 Professional Edition. If anyone wants I can mail the project to them to test it out for themselves. A quick reply would be appreciated. Thank You.

Answer 1

In the bottom code segment you use WS_OVERLAPPEDWINDOW as a window style, which is what gives you the system menu. The first code segment only has WS_OVERLAPPED, which only gives you the title bar and border.