delphi 字符串保存为 TXT文件

procedure TForm1.Timer1Timer(Sender: TObject);
var
    afile:   TFileStream;
    //DateTime : TDateTime;
    str,da,StrToWrite : string;


begin
    //DateTime := Time;  // store the current date and time
    str := TimeToStr(Time); // convert the time into a string
    da:= DateToStr(Date);
    StrToWrite:=  da+'  '+str   +   #13#10; //  #13#10 回车 换行

    if   not   FileExists( 'c:/a.txt ')   then
    begin
        try
            afile   :=   TFileStream.Create( 'c:/a.txt ',   fmCreate);
            afile.WriteBuffer(PChar(StrToWrite)^,Length(StrToWrite));
        finally
            afile.Free;
        end;
    end
    else   begin
        try
            afile   :=   TFileStream.Create( 'c:/a.txt ',   fmOpenWrite);
            afile.Seek(0,   soEnd);
            afile.WriteBuffer(PChar(StrToWrite)^,Length(StrToWrite));
        finally
            afile.Free;
        end;
    end;
end;