[NumLock]

создай пустой проект и добавь кнопку на форму:

Код:

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 }
    beforelbl: array of Integer;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  i: Integer;
begin
//  SetLength(beforelbl, 4);
  ShowMessage(IntToStr(Low(beforelbl)));
  ShowMessage(IntToStr(High(beforelbl)));
  for i:=Low(beforelbl) to High(beforelbl) do ShowMessage('>>'+IntToStr(i));
end;

end.