小问题--loadfromfile

Question

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;type
  TForm1 = class(TForm)
    Label1: TLabel;
    Memo1: TMemo;
    Button2: TButton;
    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
filename:string;
begin
filename:='f:\ie.txt';
with memo1 do
begin
loadfromfile(filename); //在此报错
SaveToFile(ChangeFileExt(FileName,'txt'));end;
end;end.报错信息：[错误] Unit1.pas(36): Undeclared identifier: 'loadfromfile'
请问为什么，请尽量详细说明

Answer 1

procedure TForm1.Button1Click(Sender: TObject);
var
filename:string;
begin
filename:='f:\ie.txt';
with memo1.lines do
begin
 loadfromfile(filename); //在此报错
 SaveToFile(ChangeFileExt(FileName,'txt'));end;
end;end.