Win32 RegisterClass Error

[Stewart Gordon]

"GaboonViper" <gaboonviper at gmx.net> wrote in message 
news:op.t1xpyxi8th8wtu at gabonica.home.nl...
<snip>
> void InitApplication()
> {
>    WNDCLASS wc;
>    wc.lpszClassName = "DWndClass";
>    wc.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
>    wc.lpfnWndProc = &WindowProc;
>    wc.hInstance = ghInstance;
>    wc.hIcon = LoadIconA(cast(HINSTANCE) null, IDI_APPLICATION);
>    wc.hCursor = LoadCursorA(cast(HINSTANCE) null, IDC_CROSS);
>    wc.hbrBackground = cast(HBRUSH) (COLOR_WINDOW + 1);
>    wc.lpszMenuName = null;
>    wc.cbClsExtra = wc.cbWndExtra = 0;
>
>    assert(RegisterClassA(&wc));

Your code is broken here.  If compiling in release mode, assert expressions 
are not evaluated, and so your window class won't be registered.

Moreover, because RegisterClass (like many Windows API functions) returns 
zero on failure, the failure of the assert would render the following 
statement useless:

>    Win32ErrorCheck("RegisterClassA", __FILE__, __LINE__);
> }
<snip>

Simplest fix:

    if (!RegisterClassA(&wc)) {
        Win32ErrorCheck("RegisterClassA", __FILE__, __LINE__);
    }

Stewart.

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