memo1 通过行号 跳转到 指定行

procedure TForm3.ToolButton11Click(Sender: TObject);    //memo1 通过行号 定位 指定行
var
  LineNumber, StartPos, LineLength: Integer;
begin
  LineNumber := strtoint(edit1.Text)-1 ;  // The line number to select (0-based)
  StartPos := Memo1.Perform(EM_LINEINDEX, LineNumber, 0);
  LineLength := Memo1.Perform(EM_LINELENGTH, StartPos, 0);
  Memo1.SelStart := StartPos;
  Memo1.SelLength := LineLength;
    Memo1.SetFocus;
end;