大家帮我看看这个程序错在哪里？万分感谢，编译通过，但是连接不行

请高手给我指点一下，万分感谢！
错误提示如下：--------------------Configuration: 3_1 - Win32 Debug--------------------
Compiling...
3_1.cpp
Linking...
LIBCD.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
Debug/3_1.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.3_1.exe - 2 error(s), 0 warning(s)程序代码如下：
#include <windows.h>LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInst,LPSTR IpCmdLine,int nCmdShow)
{
HWND hwnd;
MSG Msg;
WNDCLASS wndclass;
char lpszClassName[]="窗口";
char lpszTitle[]="my_windows";
//窗口定义wndclass.style=0;
wndclass.lpfnWndProc=WndProc;
wndclass.cbClsExtra=0;
wndclass.cbWndExtra=0;
wndclass.hInstance=hInstance;
wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName=NULL;
wndclass.lpszClassName=lpszClassName;
if(!RegisterClass(&wndclass))
    {
            MessageBeep(0);
   return FALSE;
}
hwnd=CreateWindow(lpszClassName,
                lpszTitle,
       WS_OVERLAPPEDWINDOW,
       CW_USEDEFAULT,
       CW_USEDEFAULT,
       CW_USEDEFAULT,
       CW_USEDEFAULT,
       NULL,
       NULL,
       hInstance,
       NULL);
ShowWindow(hwnd,nCmdShow);
UpdateWindow(hwnd);
while(GetMessage(&Msg,NULL,0,0))
{
  TranslateMessage(&Msg);
  DispatchMessage(&Msg);
}
  return Msg.wParam;
}
//窗口函数
LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lparam)
{
switch(message)
{
case WM_DESTROY:
   PostQuitMessage(0);
default:
  return DefWindowProc(hwnd,message,wParam,lparam);
}
return(0);
}