RegisterClassEx fails

[theranga]

I'm setting up a window class and registering, like so:

WNDCLASSEX wcBigWnd;
LRESULT CALLBACK mainWindow (HWND,UINT,WPARAM,LPARAM);

int APIENTRY WinMain (HINSTANCE hInstance, HINSTANCE hPrev, LPSTR lpCmdLine, int nCmdShow) {

HICON hIcon=NULL;

wcBigWnd.cbSize=sizeof(WNDCLASSEX);
wcBigWnd.style=0;
wcBigWnd.lpfnWndProc=mainWindow;
wcBigWnd.cbClsExtra=0;
wcBigWnd.cbWndExtra=0;
wcBigWnd.hInstance=hInstance;
wcBigWnd.hIcon=hIcon;
wcBigWnd.hCursor=NULL;
wcBigWnd.hbrBackground=(HBRUSH)COLOR_BACKGROUND;
wcBigWnd.lpszMenuName=NULL;
wcBigWnd.lpszClassName="big_window_class";
wcBigWnd.hIconSm=NULL;

std::cout << "RegisterClassEx() returns: " << RegisterClassEx(&wcBigWnd) << "\n";

std::cout << "GetLastError() returns: " << GetLastError() << "\n";

}

and it gives me the output:

RegisterClassEx() returns: 49666
GetLastError() returns: 14007

On msdn (http://msdn.microsoft.com/en-us/library/windows/desktop/ms681384%28v=vs.85%29.aspx), it says:

ERROR_SXS_KEY_NOT_FOUND

14007 (0x36B7)

The requested lookup key was not found in any active activation context.

What does this mean and how can I fix it?

EDIT: when I use this class in CreateWindowEx("big_window_class",...), it returns NULL but GetLastError() returns 0

[freddie1]

Is there code I'm not seeing? I see a function prototype ...

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

... for a mainWindow function, but I see no mainWindow function?

iostream will do you no good. If you want to know what a Windows program looks like, take a look at this minimal one. Take especial note of the fact that while I have no prototype for a Window Procedure, I do indeed have one, i.e., fnWndProc. And the address of that existing function is passed into Windows through the lpfnWndProc member of WNDCLASSEX::lpfnWndProc. The below code will only compile as an ansi build...

//Compiles to about 7K
#include <windows.h>

LRESULT CALLBACK fnWndProc(HWND hwnd, unsigned int msg, WPARAM wParam,LPARAM lParam)
{
 if(msg==WM_DESTROY)
 {
    PostQuitMessage(0);
    return 0;
 }

 return (DefWindowProc(hwnd, msg, wParam, lParam));
}


int WINAPI WinMain(HINSTANCE hIns, HINSTANCE hPrevIns, LPSTR lpszArgument, int iShow)
{
 char szClassName[]="Form1";
 WNDCLASSEX wc={};
 MSG messages;
 HWND hWnd;

 wc.lpszClassName   = szClassName;
 wc.lpfnWndProc     = fnWndProc;
 wc.cbSize          = sizeof (WNDCLASSEX);
 wc.hInstance       = hIns;
 RegisterClassEx(&wc);
 hWnd=CreateWindowEx(0,szClassName,szClassName,WS_OVERLAPPEDWINDOW,100,100,350,300,HWND_DESKTOP,0,hIns,0);
 ShowWindow(hWnd,iShow);
 while(GetMessage(&messages,NULL,0,0))
 {
    TranslateMessage(&messages);
    DispatchMessage(&messages);
 }

 return messages.wParam;
}              

Also, don't use global data. Its no good. Put your WNDCLASSEX object declaration in WinMain(), not in your program's data segment.

[EssGeEich]

The result of RegisterClassEx is an ATOM which is a numeric ID of the class.
If it fails, it returns 0.
http://msdn.microsoft.com/en-us/library/windows/desktop/ms633587(v=vs.85).aspx

[theranga]

@freddie1: that function prototype is just for the window procedure

I think the problem is line 16, where it gives a handle to something that isn't a brush - this would explain the error (the resource given in (HBRUSH)COLOR_BACKGROUND doesn't exist)

[theranga]

That was the problem after all. Thanks people for your input!