用WinInet API下载网页资源为何错？头文件是“wininet.h” 还是"afxinet.h"代码是。。。

HINTERNET hSession=::InternetOpen(NULL,INTERNET_OPEN_TYPE_PRECONFIG,"",INTERNET_INVALID_PORT_NUMBER,0);
HINTERNET hConnect = ::InternetConnect(hSession,"http://www.csdn.net",INTERNET_DEFAULT_HTTP_PORT,"","",INTERNET_SERVICE_HTTP,NULL,NULL);
HINTERNET hOpenR = ::HttpOpenRequest(hConnect,"GET","/",HTTP_VERSION,NULL,0,INTERNET_FLAG_DONT_CACHE,0);
BOOL SendFlag = HttpSendRequest(hOpenR,NULL,-1,NULL,0);
char lpvBuffer[32];
DWORD  lpdwBufferLength = sizeof(lpvBuffer);
BOOL QueryFlag = ::HttpQueryInfo(hOpenR,
HTTP_QUERY_CONTENT_LENGTH,
&lpvBuffer,
&lpdwBufferLength,
NULL);

if (QueryFlag)
{
DWORD dwFileSize = (DWORD)atoi(lpvBuffer);
char  *lpszBuf = NULL;
lpszBuf = new char[dwFileSize];
BOOL bReadFlag = ::InternetReadFile(hOpenR,
lpszBuf,
dwFileSize,
&dwFileSize);

AfxMessageBox(lpszBuf);

delete [] lpszBuf;

}
::InternetCloseHandle(hOpenR);