用Array类的Sort，Reverse方法对数组进行排序

Array.Reverse是反向输出数组；

Array.Sort是对数组进行排序；

小例子：

  class Program
    {
        static void Main(string[] args)
        {
            int[] arr1 = new int[] { 1,3,8,5,39,2,4,6,7}; //输出一个数组
            foreach (int n in arr1)
                Console.Write(n+" ");
            Console.WriteLine();

            Array.Reverse(arr1);                          //倒叙输出arr1
            foreach (int a in arr1)
                Console.Write(a+" ");          
            Console.WriteLine();
            
            Array.Sort(arr1);                              //排序输出从小到大
            foreach (int s in arr1)
                Console.Write(s+" ");
            Console.WriteLine();

            int[] b = arr1;                                 //倒叙输出上一层从小到大变为从大到小
            Array.Reverse(b);
            foreach (int d in b)
                Console.Write(d+" ");

            Console.ReadLine();

        }
    }

输出结果：

1 3 8 5 39 2 4 6 7
7 6 4 2 39 5 8 3 1
1 2 3 4 5 6 7 8 39
39 8 7 6 5 4 3 2 1