急求

求助：为什么编译没错误但弹不出窗口（程序会在后台运行没有窗口）
求大神帮助
附代码：
#include<windows.h>
#include<stdio.h>
LRESULT CALLBACK WinSunProc(
HWND hwnd, // handle to window
UINT uMsg, // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
);
int WINAPI WinMain(
HINSTANCE hInstance, // handle to current instance
HINSTANCE hPrevInstance, // handle to previous instance
LPSTR lpCmdLine, // command line
int nCmdShow // show state
)
{
WNDCLASS wndcls;
wndcls.cbClsExtra=0;
wndcls.cbClsExtra=0;
wndcls.hbrBackground=(HBRUSH)GetStockObject(BLACK_BRUSH);
wndcls.hCursor=LoadCursor(NULL,IDC_CROSS);
wndcls.hIcon=LoadIcon(NULL,IDI_INFORMATION);
wndcls.hInstance=hInstance;
wndcls.lpfnWndProc=WinSunProc;
wndcls.lpszClassName="d2018";
wndcls.lpszMenuName=NULL;
wndcls.style=CS_HREDRAW|CS_VREDRAW;
RegisterClass(&wndcls);
HWND hwnd;
hwnd=CreateWindow("d2018","窗口",WS_OVERLAPPEDWINDOW,0,0,500,400,HWND_DESKTOP,NULL,hInstance,NULL);
if(!hwnd) return FALSE;
ShowWindow(hwnd,nCmdShow);
UpdateWindow(hwnd);
MSG msg;
while(GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WinSunProc(
HWND hwnd, // handle to window
UINT uMsg, // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
)
{
switch(uMsg)
{
case WM_CHAR:
char szChar[20];
sprintf(szChar,"char is d%",wParam);
MessageBox(hwnd,szChar,"char",0);
break;
case WM_LBUTTONDOWN:
MessageBox(hwnd,"i love you","窗口",0);
HDC hdc;
hdc=GetDC(hwnd);
TextOut(hdc,0,50,"你好",strlen("你好"));
ReleaseDC(hwnd,hdc);
break;
case WM_PAINT:
HDC hDC;
PAINTSTRUCT ps;
hDC=BeginPaint(hwnd,&ps);
TextOut(hDC,0,0,"窗口",strlen("窗口"));
EndPaint(hwnd,&ps);
break;
case WM_CLOSE:
if(IDYES==MessageBox(hwnd,"是否退出?","窗口",MB_YESNO))
{
DestroyWindow(hwnd);
}
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd,uMsg,wParam,lParam);
}
return 0;
}