int[] nameArray = new int[]
        {
            1,
            2,
            3
        };

        Array.Resize(ref nameArray, 4);
        nameArray[3] = 4;

        lblArray.Text = Convert.ToString(nameArray[3]);

        List<int> nameList = new List<int>
        {
            1,
            2,
            3
        };

        nameList.Add(4);

        lblList.Text = Convert.ToString(nameList[3]);