一个windows编程的问题
#include "windows.h "

LRESULT CALLBACK WinProc(
HWND hwnd, // handle to window
UINT uMsg, // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
);
int WINAPI WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPTSTR lpCmdLine,
int nShowCmd)
{
WNDCLASSEX wndclass;

wndclass.cbClsExtra=0;
wndclass.cbWndExtra=0;
wndclass.cbSize=sizeof(WNDCLASSEX);
wndclass.hbrBackground=(HBRUSH)GetStockObject(BLACK_BRUSH);
wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
wndclass.hIcon=LoadIcon(NULL,IDI_QUESTION);
wndclass.hIconSm=LoadIcon(NULL,IDI_QUESTION);
wndclass.hInstance=hInstance;
wndclass.lpfnWndProc=WinProc;
wndclass.lpszClassName= "abc ";
wndclass.lpszMenuName=NULL;
wndclass.style=CS_HREDRAW|CS_VREDRAW;

RegisterClassEx(&wndclass);

HWND hwnd;
hwnd=CreateWindow // <---expression cannot be eveluated!!( "abc ", "title ",WS_POPUP,0,0,640,480,NULL,NULL,hInstance,NULL);

ShowWindow(hwnd,SW_SHOWNORMAL);
UpdateWindow(hwnd);


MSG msg;
while(true)
{
if(PeekMessage(&msg,NULL,0,0,PM_REMOVE))
{
if(GetAsyncKeyState(VK_ESCAPE) <0)
break;
TranslateMessage(&msg);
DispatchMessage(&msg);
}


}

return(0);
}

LRESULT CALLBACK WinProc(
HWND hwnd, // handle to window
UINT uMsg, // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
)
{
switch(uMsg)
{
default:
return DefWindowProc(hwnd,uMsg,wParam,lParam);
}
return(1);
}

在以上的这段代码中，我单步跟踪调试的时候发现hwnd句柄从头到尾都是
Error:expression cannot be eveluated
这是为什么？

[解决办法]
hwnd,已经不为NULL了，说明已经成功创建了，程序已经正确执行了，
至于Error:expression cannot be eveluated ，只是调试器不支持你通过hwnd了解该句柄更详细的信息，不知道你理他做甚？