unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    GroupBox1: TGroupBox;
    Label1: TLabel;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Memo1: TMemo;
    OpenDialog1: TOpenDialog;
    SaveDialog1: TSaveDialog;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

Var
  ATextFile:TextFile;

procedure TForm1.Button1Click(Sender: TObject);
begin
  With OpenDialog1 do
  if execute then
  begin
    Label1.Caption:='當(dāng)前打開(kāi)的文件:'+FileName+'';
    if FileName<>'' then
    begin
      AssignFile(ATextFile,Opendialog1.FileName);
      ShowMessage('文件變量和具體的磁盤文件成功建立關(guān)聯(lián)');
      Button2.Enabled:=True;
      Memo1.lines.Clear;
    end;
  end;
  end;
end;

procedure TForm1.Button2Click(Sender: TObject);
Var TextStrString;
begin
  if MessageDtg('是否選擇只讀(Reset)模式打開(kāi)該文本文件?'mtConfimation
      [mbYes,mbNo],0)=mrYes then
    begin
      Memo1.ReadOnly:=True;
      Button3.Enabled:=False;
    end;
  else
    begin
      Memo1.ReadOnly:=False;
      Button3.Enabled:=True;
    end;
    Reset(ATextFile);
    Memo1.Lines.Clear;
    Memo1.Lines.BeginUpdate;
    try
      While Not Eof(ATextFile) do
      begin
        Readln(ATextFile,TextStr);
        Memo1.Lines.Add(TextStr);
      end
    finally
      Memo1.Lines.EndUpdate;
      CloseFile(ATextFile);
    end
end;

procedure TForm1.Button3Click(Sender: TObject);
Var
  i:=Integer;
begin
  Rewrite(ATextFile);
  try
    for i:=0 to Memo1.lines.Count-1 do
      begin
        Writeln(AtextFile,Memo1.lines[i])
      end;
      ShowMessage('該文件已經(jīng)被成功保存到磁盤上！');
  finally
    CloseFile(ATextFile);
  end
end;

end.