注册窗口类时出错

[bcjava]

源程序如下：
WNDCLASS wndclass;
wndclass.style =CS_HREDRAW|CS_VREDRAW;
wndclass.lpfnWndProc =WndProc;
wndclass.cbClsExtra =0;
wndclass.hInstance =0;
wndclass.hIcon =LoadIcon(NULL,IDI_APPLICATION);
wndclass.hCursor =LoadCursor(NULL,IDC_ARROW);
wndclass.hbrBackground =(HBRUSH)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName =NULL;
wndclass.lpszClassName =szClassName;

if(!RegisterClass(&wndclass))
{
MessageBox(NULL,TEXT("Error!"),
szAppName,MB_ICONERROR);
return 0;
}

执行时弹出了Error对话框,(windows xp操作系统),请教一下这是怎么回事，谢谢:_)

[rorot]

// 改这里
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;

[zhouqingyuan]

wndclass.hInstance =0;//不能为0，要赋值

The executable or DLL that registered the class is the owner of the class. The system determines class ownership from the hInstance member of the WNDCLASSEX structure passed to the RegisterClassEx function when the class is registered. For DLLs, the hInstance member must be the handle to the .dll instance.

[zhouqingyuan]

Although a complete window class consists of many elements, the system requires only that an application supply a class name, the window-procedure address, and an instance handle.


注册时候，有三个元素是不能缺省的，
wndclass.lpszClassName wndclass.lpfnWndProc wndclass.hInstance