Problem with SetWindowLongPtr

This is a discussion on Problem with SetWindowLongPtr within the Windows Programming forums, part of the Platform Specific Boards category; Hi! I've got a problem with using SetWindowLongPtr. I tried using this code, but it doesn't seem to work: Code: ...

  1. #1
    tin
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    Unhappy Problem with SetWindowLongPtr

    Hi!

    I've got a problem with using SetWindowLongPtr. I tried using this code, but it doesn't seem to work:

    Code:
    LONG toolWindowExStyle = WS_EX_TOOLWINDOW;
    ShowWindow(hwnd, SW_HIDE);
    
    SetWindowLongPtr(hwnd, GWL_EXSTYLE, (LONG_PTR) &toolWindowExStyle);
    
    ShowWindow(hwnd, SW_SHOW);

    However, this works perfectly:

    Code:
    ShowWindow(hwnd, SW_HIDE);
    
    SetWindowLong(hwnd, GWL_EXSTYLE, WS_EX_TOOLWINDOW);
    
    ShowWindow(hwnd, SW_SHOW);
    I'd really appreciate it if someone could point out the mistake.

    Thanks!

    PS: BTW, I'm using Windows XP, Microsoft Visual Studio 2005 and have used "#undef UNICODE" and "#undef _UNICODE" on top of the source code.

  2. #2
    tin
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    Question Got the solution, but an explanation?

    Hi!

    I just figured out from looking at source code on the 'net that I can use:

    ShowWindow(hwnd, SW_HIDE);
    SetWindowLongPtr(hwnd, GWL_EXSTYLE, WS_EX_TOOLWINDOW);
    ShowWindow(hwnd, SW_SHOW);

    However, isn't WS_EX_TOOLWINDOW supposed to be a LONG rather than a pointer to a LONG? I mean I thought the function expected a pointer to a long so I initially tried giving it a pointer to a long.

    -Confused

  3. #3
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    The function takes a LONG, not a pointer to LONG.

  4. #4
    Registered User mrafcho001's Avatar
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    Code:
    LONG_PTR SetWindowLongPtr(      
    
        HWND hWnd,
        int nIndex,
        LONG_PTR dwNewLong
    );
    --MSDN

    It does infact expect a pointer to a LONG.
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  5. #5
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    No it doesnt. If you look in the intsafe.h or baseTsd.h header file, you will see
    Code:
    typedef [public]          __int3264 LONG_PTR;
    The fact that the type name has PTR stuck at the end means absolutely nothing. The LONG_PTR variable is used whenever a pointer is casted to a signed long.

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