在 Delphi 中打开/操作/保存文本文件

Question

我是 Delphi Noob，我已经搜索并逐步浏览了我的代码，但不明白为什么会输出一个没有内容的文本文件。它应该在有效的对话框中打开一个文本文件，它分配所选文件origFile，然后我想将该文件分配给另一个名为myFile 的文件，这样我就可以在不改变实际原始文件的情况下进行操作，然后我想将myFile 保存为(sOrigFileName + 'B.BACKWARDS.TXT')，但它会跳过while not Eof(origFile) do 并转到CloseFile。我在下面发布我的代码。

要求是使用TextFile 与TStringList，否则我会使用TStringList 完成此操作。另一个问题是它指出myFile 没有找到，我认为assignFile(myFile, sOrigFileName); 正在创建myFile....

procedure TForm1.btnOpenFileCClick(Sender: TObject);
var
    origFile, myFile : TextFile;
    OpenDialog1 : TOpenDialog;
    sOrigFileName, sNewFileName, sLine, sNewLine : String;

begin
    //Selects txt File of the users choosing
    OpenDialog1 := TOpenDialog.Create(self);
    OpenDialog1.Filter := '*.txt';

    if OpenDialog1.Execute then
    begin
      //AssignFile(origFile, OpenDialog1.FileName);
      sOrigFileName := OpenDialog1.FileName;
      AssignFile(origFile, sOrigFileName);
    end;

    //BACKWARDS
    sNewFileName := sOrigFileName + '.B.BACKWARDS.TXT';
    DeleteFile(sNewFileName);  //Delete old File if exists
    AssignFile(myFile, sNewFileName);

    Reset(origFile);

    while not Eof(origFile) do
    begin
       Rewrite(myFile);
       Readln(origFile, sLine); //takes line into a string Var
       sNewLine := AnsiReverseString(sLine); //reverses and places to  new Var
       WriteLn(myFile,sNewLine);
    end;

    //Clean up
    CloseFile(OrigFile);
    CloseFile(myFile);

Answer 1

试试这个：

procedure TForm1.btnOpenFileCClick(Sender: TObject);
var
  origFile, myFile : TextFile;
  OpenDialog1 : TOpenDialog;
  sOrigFileName, sNewFileName, sLine, sNewLine : String;
begin
  OpenDialog1 := TOpenDialog.Create(nil);
  try
    OpenDialog1.Filter := '*.txt';
    if not OpenDialog1.Execute then
      Exit;
    sOrigFileName := OpenDialog1.FileName;
  finally
    OpenDialog1.Free;
  end;

  sNewFileName := sOrigFileName + '.B.BACKWARDS.TXT';
  DeleteFile(sNewFileName);

  AssignFile(origFile, sOrigFileName);
  try
    Reset(origFile);

    AssignFile(myFile, sNewFileName);
    try
      Rewrite(myFile);

      while not Eof(origFile) do
      begin
        Readln(origFile, sLine);
        sNewLine := AnsiReverseString(sLine);
        WriteLn(myFile, sNewLine);
      end;
    finally
      CloseFile(myFile);
    end;
  finally
    CloseFile(OrigFile);
  end;
end;

我不知道您为什么需要使用TextFile，这是一种非常古老的学校方法，一点也不现代。如果您有权访问它们，则应使用TStreamReader/Writer：

procedure TForm1.btnOpenFileCClick(Sender: TObject);
var
  origFile: TStreamReader;
  myFile : TStreamWriter;
  OpenDialog1 : TOpenDialog;
  sOrigFileName, sNewFileName, sLine, sNewLine : String;
begin
  OpenDialog1 := TOpenDialog.Create(nil);
  try
    OpenDialog1.Filter := '*.txt';
    if not OpenDialog1.Execute then
      Exit;
    sOrigFileName := OpenDialog1.FileName;
  finally
    OpenDialog1.Free;
  end;

  sNewFileName := sOrigFileName + '.B.BACKWARDS.TXT';
  DeleteFile(sNewFileName);

  origFile := TStreamReader.Create(sOrigFileName);
  try
    myFile := TStreamWriter.Create(sNewFileName, False, origFile.CurrentEncoding);
    try
      while not origFile.EndOfStream do
      begin
        sLine := origFile.ReadLine;
        sNewLine := AnsiReverseString(sLine);
        myFile.WriteLine(sNewLine);
      end;
    finally
      myFile.Free;
    end;
  finally
    OrigFile.Free;
  end;
end;

否则，请改用TStringList：

procedure TForm1.btnOpenFileCClick(Sender: TObject);
var
  myFile : TStringList;
  OpenDialog1 : TOpenDialog;
  sOrigFileName, sNewFileName, sLine, sNewLine : String;
  I: Integer;
begin
  OpenDialog1 := TOpenDialog.Create(nil);
  try
    OpenDialog1.Filter := '*.txt';
    if not OpenDialog1.Execute then
      Exit;
    sOrigFileName := OpenDialog1.FileName;
  finally
    OpenDialog1.Free;
  end;

  sNewFileName := sOrigFileName + '.B.BACKWARDS.TXT';
  DeleteFile(sNewFileName);

  myFile := TStringList.Create;
  try
    myFile.LoadFromFile(sOrigFileName);

    for I := 0 to myFile.Count-1 do
    begin
      sLine := myFile[I];
      sNewLine := AnsiReverseString(sLine);
      myFile[I] := sNewLine;
    end;

    myFile.SaveToFile(sNewFileName);
  finally
    myFile.Free;
  end;
end;

Answer 2

在我看来，您好像需要将 Rewrite(myFile) 放在循环之外，紧跟在 Reset(origFile) 之后。