"error LNK2001: unresolved external symbol _main!"应该怎么改！

以下这个例子完全按书上的,为什么不会出错:
#include<windows.h>
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
int WINAPI WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInst,
LPSTR lpszCmdLine,
int nCmdShow)
{
HWND hwnd;
MSG Msg;
WNDCLASS wndclass;
char lpszClassName[]="窗口";
char lpszTitle[]="My_Windows";
//窗口类的定义
wndclass.style=0;
wndclass.lpfnWndProc=WndProc;
wndclass.cbWndExtra=0;
wndclass.hInstance=hInstance;
wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
wndclass.hbrBackground=(HBRUSH) COLOR_BACKGROUND;
wndclass.lpszMenuName=NULL;
wndclass.lpszClassName=lpszClassName;
//以下进行窗口类的注册
if(!RegisterClass(&wndclass)){
MessageBeep(0);
return FALSE;
}
//创建窗口
hwnd=CreateWindow(lpszClassName,
lpszTitle,
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
HWND_DESKTOP,
NULL,
hInstance,
NULL);
//显示窗口
ShowWindow(hwnd,nCmdShow);
//绘制用户区
UpdateWindow(hwnd);
//消息循环
while(GetMessage(&Msg,NULL,0,0)){
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam; //消息循环结束即程序终止时将信息返回系统
}

//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);
}



--------------------Configuration: WinApi - Win32 Debug--------------------
Compiling...
WinApi.cpp
Linking...
LIBCD.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
Debug/WinApi.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

WinApi.exe - 2 error(s), 0 warning(s)
要怎样设置才能通过呢?望高手指教.