MFC基于单文档写unicode的文件

• 环境VS2010

CFile file(FilePathName_new,CFile::modeCreate | CFile::modeWrite);
FilePathName = fileDlg.GetPathName();
file.SeekToBegin();
file.Write(“\xff\xfe”, 2);//UNICODE编码的头
file.Write(str,str.GetLength()*2);
file.Flush();