TFindDialog/zh CN

procedure TForm1.Button1Click(Sender: TObject);
begin
  FindDialog1.Execute();
end;

procedure TForm1.FindDialog1Find(Sender: TObject);
var
  k: integer;
begin
  with Sender as TFindDialog do begin
    k := Pos(FindText, Memo1.Lines.Text);
    if k > 0 then begin
      Memo1.SelStart := k - 1;
      Memo1.SelLength := Length(FindText);
      Memo1.SetFocus; //必须激活控件，否则不显示选择效果
    end else
      Beep();
  end;
end;

uses
  StrUtils;

type
  TForm1 = class(TForm)
  private
    FFoundPos: Integer;
    ...

procedure TForm1.Button1Click(Sender: TObject);
begin
  with FindDialog1 do 
  begin
    if frEntireScope in Options then    // Search begins at file start
      FFoundPos := 0
    else
      FFoundPos := Memo1.SelStart;      // Serach begins at current cursor position
    Execute;
  end;
end; 

procedure TForm1.FindDialog1Find(Sender: TObject);
begin
  with Sender as TFindDialog do 
  begin
    FFoundPos := PosEx(FindText, Memo1.Lines.Text, FFoundPos+1);
    if FFoundPos > 0 then 
    begin
      Memo1.SelStart := FFoundPos - 1;
      Memo1.SelLength := Length(FindText);
      Memo1.SetFocus; //必须激活控件，否则不显示选择效果
    end else
      Beep();
  end;
end;