delphi 数组跟for

如何用数组跟for打印出下面的图形
*
**
***
****

如果有更好的方法最好也写上 XX

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procedure TForm1.Button2Click(Sender: TObject);
var
  arr: array of Integer;
  i,j: Integer;
  stra,strb : string;
begin
  setlength(arr,4);
  for i := 0 to 3 do
  begin
    arr[i] := i+1;
  end;

  for i := 0 to high(arr) do
  begin
    stra := '';
    for j := 0 to i do
    begin
      stra := stra + '*';
    end;
    strb := strb + stra + #13;
  end;
  ShowMessage(strb);
end;