unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
procedure Button1Click(Sender: TObject);
  private
{ Private declarations }
  public
{ Public declarations }
end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
   text:String;
   f:TextFile ;
const
   filedir= 'c:\temp\test.txt';
begin
if not FileExists(filedir) then   //这里用到了一个判断文件是否存在的函数
begin
      ShowMessage('测试文件'+filedir+'不存在');
      Exit;
end
else
begin

         AssignFile(f,filedir);  //这里我们用到了AssignFile过程下面一节我会给大家介绍这个过程
         Append(f); //将文件指针定位到文件的末尾;
         write(f,'程序人生');//向文件Test.txt文件末尾写入数据”程序人生“;
         CloseFile(f); //对这个文件操作结束了，当然我们要关闭这个文件;

end;

end;

end.