Windows newbie question

This is a discussion on Windows newbie question within the Windows Programming forums, part of the Platform Specific Boards category; I was wondering if anyone can tell me what is wrong with this code: Code: #include <windows.h> LRESULT CALLBACK WndProc(HWND ...

  1. #1
    Registered User Dohojar's Avatar
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    Question Windows newbie question

    I was wondering if anyone can tell me what is wrong with this code:
    Code:
    #include <windows.h>
    
    LRESULT CALLBACK WndProc(HWND hWnd, UINT uiMessage,
                             WPARAM wParam, LPARAM lParam);
    void Display_Windows_Error(void);
    
    HINSTANCE hInstGlobal;
    
    int APIENTRY WinMain(HINSTANCE hInstance,
                         HINSTANCE PrevInstance, 
                         LPSTR lpCmdLine, 
                         int nShowCmd)
    {
       WNDCLASS WndClass;
    
       WndClass.style = 0;
       WndClass.cbClsExtra = 0;
       WndClass.cbWndExtra = 0;
       WndClass.lpfnWndProc = WndProc;
       WndClass.hInstance = hInstance;
       WndClass.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
       WndClass.hCursor = LoadCursor(NULL,IDC_ARROW);
       WndClass.hIcon = LoadIcon(NULL,IDI_APPLICATION);
       WndClass.lpszMenuName = 0;
       WndClass.lpszClassName = "WinProgram4";
       
    
       if(RegisterClass(&WndClass) == 0)
           return(1);
       HWND hWindow;
       hWindow = CreateWindow(WinProgram4","Window",
                              WS_OVERLAPPEDWINDOW,0,0
                              400,400,NULL,NULL,hInstance,NULL);
       if(hWindow == NULL)
       {
          Display_Windows_Error();
          return(1);
       }
       ShowWindow(hWindow,nShowCmd);
       UpdateWindow(hWindow);
    
       MSG Message;
       while(GetMessage(&Message,NULL,0,0))
       {  DispatchMessage(&Message); }
       
       return(Message.wParam);
    }
    Basically the problem is this..... after the CreateWindow function I am checking to see if the hWindow is NULL and it is.Display_Windows_Error() is just a function to show me the what the error was. It calls GetLastError() function and FormatMessage() functions to tell me what went wrong. The error I am getting is "invalid Window Handle" and I can't figure out why. If anyone can tell me what is going wrong I would greatly appreciate it.
    Dohojar Moajbuj
    Time is the greatest teacher, too bad it kills all its students

  2. #2
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    hWindow = CreateWindow("WinProgram4","Window",
    WS_OVERLAPPEDWINDOW,0,0,
    400,400,NULL,NULL,hInstance,NULL);

    Syntax errors in the code you posted.

  3. #3
    Registered User Dohojar's Avatar
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    That is was not the problem. That is just my bad typing. If it was a syntax that was the problem I would be a happy camper
    My problem is hWindow being NULL.
    Dohojar Moajbuj
    Time is the greatest teacher, too bad it kills all its students

  4. #4
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    Post

    Just so you know, I'm Unregistered above.

    I know that was'nt THE problem, I was just stating that the code you posted had syntax errors.

    Regarding the code, I'm no expert but it seems pretty messed up lol. I tried to fix it.

  5. #5
    Used Registerer jdinger's Avatar
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    One thing I noticed is that you never populated your hInstGlobal
    variable.

    Code:
    hInstGlobal=hInstance;
    WndClass.hInstance=hInstGlobal;
    CreateWindow(blah...blah..blah,,,hInstGlobal,...);
    You also left out WS_VISIBLE in the dwStyle param of the
    CreateWindow call.

    And your passing 0 as your WndClass.style. I could be wrong but
    I've never seen 0 passed there.

  6. #6
    Registered User Dohojar's Avatar
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    Hmm ...... thanks for the advice. This code is from a book, not my own. hInstGlobal is used in the WndProc function. The code I posted was by no means complete. I just want to know why hWindow is NULL.
    Just so I know, jizzer, What is wrong with the code I posted. You said it seemed pretty messed up. In what way? I am a total newbie to windows programming so I don't know if the book I am using is the right way or wrong way.
    Dohojar Moajbuj
    Time is the greatest teacher, too bad it kills all its students

  7. #7
    Used Registerer jdinger's Avatar
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    Not sure what book you're learning from, but I notice you're using
    WNDCLASS, CreateWindow and RegisterClass. These 3 have been
    superceded by WNDCLASSEX, CreateWindowEx and
    RegisterClassEX. Of course I'm not saying that using the older
    versions are the problem, just something to think about.

  8. #8
    Registered User Dohojar's Avatar
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    Ahhh I see. Yea I knew about that from reading microcraps help documents. Thanks for the info though
    Dohojar Moajbuj
    Time is the greatest teacher, too bad it kills all its students

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