Something

 sub randomGenerator()
    {
        for ($i = 0; $i < 5; $i++)
        {
                 $num = int(rand(40)) + 1;


            if ( exists $randomNumbers[$num] )          {
                print $num . " already in\r\n";
            }
            else {
                $randomNumbers[$i] = $num;
            }

        }
    }