引言: 我想把一个目录和这个目录下的所有子目录，中的所有文件，写入到一个.txt文件中，应该怎么做?

function AppendOrWriteTextToFile(FileName: TFilename; 
      WriteText: string): Boolean;
  var
    f: Textfile;
  begin
    Result := False;
    AssignFile(f, FileName);
    try
      if FileExists(FileName) = False then
      Rewrite(f)
    else
      begin
        Reset(f);
        Append(f);
    end;
      Writeln(f, WriteText);
      Result := True;
    finally
      CloseFile(f);
  end;
end;    //例子
procedure TForm1.Close1Click(Sender: TObject);
  var
    dir, log: string;
  begin
    dir := ExtractFilePath(Application.Exename);
    log := 'Last Programm Termination: '   DateTimeToStr(now);
    AppendOrWriteTextToFile(dir   '\logfile.txt', log)
  end; 

procedure TForm1.Button1Click(Sender: TObject);
begin
   ShowAllFile(Edit1.Text);
end;    procedure TForm1.ShowAllFile(InDir: String);
var
  sr: TSearchRec;
  FileAttrs: Integer;
begin
  if FindFirst(InDir '\*.*', faAnyFile, sr) = 0 then begin
     Memo1.Lines.Add( InDir   ' [DIR]');
     while FindNext(sr) = 0 do begin
           if (sr.Name = '.') or (sr.Name = '..') then continue;
           if ((sr.Attr and faDirectory) = faDirectory) then
              ShowAllFile(InDir   '\'   sr.Name)
           else
              Memo1.Lines.Add( '   ' sr.Name   ' [File]');
           Application.ProcessMessages;
     end;
  end;
  FindClose(sr);
end;