CArichive每次读写一行

CFile myFile(_T( " tt1.txt " ), CFile::modeCreate  |  CFile::modeReadWrite);

    CArchive ar( & myFile, CArchive::store);

    ar.WriteString( " nihao " ); // msdn上本函数每次写入一行，测试失败
    ar.WriteString(_T( " \n " ));
    ar.WriteString( " 3 " );
    ar.WriteString(_T( " \n " ));

    ar.WriteString( " 4s dsf " );
    ar.WriteString(_T( " \n " ));

    ar.WriteString( "    hello worlds   " );
    ar.WriteString(_T( " \n " ));

    ar.Close();

    myFile.SeekToBegin();
    
    CArchive arLoad( & myFile, CArchive::load);
    CString stmp;
    CString ss;
    arLoad.ReadString(ss); // 可以读入一行，没错
    stmp += ss + " \n " ;
    arLoad.ReadString(ss);
    stmp += ss + " \n " ;
    arLoad.ReadString(ss);
    stmp += ss + " \n " ;
    arLoad.ReadString(ss);
    stmp += ss + " \n " ;
    arLoad.ReadString(ss);
    stmp += ss + " \n " ;

    MessageBox(stmp);

    arLoad.Close();
    myFile.Close();