delphi 读取和写入文件

【实例简介】
【实例截图】

【核心代码】

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    btnWrite: TButton;
    btnRead: TButton;
    btnAppend: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    procedure FormShow(Sender: TObject);
    procedure btnWriteClick(Sender: TObject);
    procedure btnReadClick(Sender: TObject);
    procedure btnAppendClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  sFileName: string;
implementation

{$R *.dfm}
     //把Edit2.text 写入到文件中
procedure TForm1.btnAppendClick(Sender: TObject);
var f: TextFile;
    i: integer;
    s: string;
    t: TTime;
begin
    AssignFile(f,sFileName);
  if not FileExists(sFileName) then
  begin
    ShowMessage('文件不存在。');
    exit;
  end;
  Append(f);
  for i := 0 to 999 do
  begin
    s:=TimeToStr(Now);
    WriteLn(f,s);

  end;
  CloseFile(f);

end;

procedure TForm1.btnReadClick(Sender: TObject);
var f: TextFile;
    s: string;
    ss: TStringList;
begin
  AssignFile(f,sFileName);
  ss:=TStringList.Create;
  if not FileExists(sFileName) then
  begin
    ShowMessage('文件不存在。');
    exit;
  end;
  //if file really exists,
  Reset(f); // Open this file, for Read Only
  while not Eof(f) do
  begin
    ReadLn(f,s);
    ss.Add(s);
    //Memo1.Lines.Add(s);  // 慢
  end;
  CloseFile(f);
  Memo1.Lines:=ss;
  ss.Free;

end;

procedure TForm1.btnWriteClick(Sender: TObject);
var f: TextFile;
begin
  AssignFile(f,sFileName);
  if FileExists(sFileName) then
  begin
    Append(f);//打开已经存在的文件，并移动文件指针到文件尾

  end else begin
    ReWrite(f);//创建并打开

  end;

  WriteLn(f,Edit2.Text);

  CloseFile(f);

end;

procedure TForm1.FormShow(Sender: TObject);
begin
  sFileName:=ExtractFilePath(Application.ExeName) '123.txt';
  Caption:='Application.ExeName=' Application.ExeName;
  Edit1.Text:='sFileName: ' sFileName;
end;

end.