int[,] arr2 = { { 1, 2, 3 }, { 4, 5, 6 } };
            Console.Write("数组的行数为:");
            Console.Write(arr2.Rank);
            Console.Write("\n>");
            Console.Write("数组的列数为:");
            Console.Write(arr2.GetUpperBound(arr2.Rank-1)+1);
            Console.Write("\n>");
            for (int i = 0; i < arr2.Rank; i++)
            {
                string s ="";
                for (int j = 0; j < arr2.GetUpperBound(arr2.Rank - 1) + 1; j++)
                {
                    s = s + Convert.ToString(arr2[i, j]) + "";
                }
                Console.Write("s");
                Console.Write("\n>");
            }
 这个代码为什么输不出s的值，还有arr2.GetUpperBound(arr2.Rank - 1)+1能不能解释一下吗?