Error: Implicit conversion from void*

This is a discussion on Error: Implicit conversion from void* within the Windows Programming forums, part of the Platform Specific Boards category; I get this error when I try to compile the follow line of code: ANSI C++ forbids implicit conversion from ...

  1. #1
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    Exclamation Error: Implicit conversion from void*

    I get this error when I try to compile the follow line of code:

    ANSI C++ forbids implicit conversion from `void *' in argument passing

    referring to:

    UnregisterClass( "Window", wc.hInstance );//wc is a WNDCLASSEX

    AHH...why won't it just work! And why does it say 'void *'; I don't even see that anywhere in the source or headers for the class.

  2. #2
    train spotter
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    void * = (roughtly) char * = byte *

    Unless you are using a pointer to your winclass wc , then use wc->hInstance, I get no problem with MSVC 5 / 97 but I use C no ++.
    "Man alone suffers so excruciatingly in the world that he was compelled to invent laughter."
    Friedrich Nietzsche

    "I spent a lot of my money on booze, birds and fast cars......the rest I squandered."
    George Best

    "If you are going through hell....keep going."
    Winston Churchill

  3. #3
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    It's because hInstance member of WNDCLASSEX is of type HANDLE which is internally defined as (void *). UnregisterClass () awaits HINSTANCE type as the second argument. This type is probably something else. ANSI C++ forces programmer to cast (void *) pointers to proper types before passing them as arguments. This line solves your problem:

    UnregisterClass ( "Window", (HINSTANCE) wc.hInstance );

  4. #4
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    In MSVC 5 / 97

    WNDCLASSEX hInstance is recorded as a HANDLE in the help but is declared as a HINSTANCE in its header.

    Not that this helps anyone...
    "Man alone suffers so excruciatingly in the world that he was compelled to invent laughter."
    Friedrich Nietzsche

    "I spent a lot of my money on booze, birds and fast cars......the rest I squandered."
    George Best

    "If you are going through hell....keep going."
    Winston Churchill

  5. #5
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    While it is true in VC++ 4 to 6, casting hInstance to HINSTANCE is
    unneeded. Guest didn't state what version of compiler he has. There's no problem if it is Visual 5.

  6. #6
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    Thanks everybody! I got it working right now.

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