public void main()
        {
            //可以存储任何类型的数组
            ArrayList alist = new ArrayList();

            AddData(alist);
            RemoveData(alist);
            UpdateData(alist);
            SearchData(alist);
            OtherFun(alist);
        }

        /// <summary>
        /// 往集合加数据
        /// </summary>
        /// <param name="alist"></param>
        public void AddData(ArrayList alist)
        {
            alist.Add(0);
            alist.Add(1.1);
            alist.Add("test");
            alist.Add(true);

            alist.Add(new int[] { 1, 2 });  //增加一个数组，增加了1个

            //批量添加
            alist.AddRange(new int[] { 1, 2 });//匹配增加一个数据，增加了2个

            alist.AddRange(new List<string>() { "test1", "test2" });

            alist.Insert(1, "test3");
        }

        /// <summary>
        /// 移除集合数据
        /// </summary>
        /// <param name="alist"></param>
        public void RemoveData(ArrayList alist)
        {
            //移除：
            alist.Remove(0);
            alist.RemoveAt(1);
            alist.RemoveRange(1, 2);

        }

        /// <summary>
        /// 修改集合数据
        /// </summary>
        /// <param name="alist"></param>
        public void UpdateData(ArrayList alist)
        {
            //修改
            alist[0] = 4;
            alist.SetRange(0, new string[] { "a", "b" });

            //for里面可以修改数据
            for (int i = 0; i < alist.Count; i++)
            {
                alist[i] = 4;
            }

            //查询:foreach里面，不运行修改、删除、增加集合
            foreach (object val in alist)
            {
                alist[0] = 1;  //System.InvalidOperationException:“集合已修改；可能无法执行枚举操作。”
            }
        }

        /// <summary>
        /// 查询集合数据
        /// </summary>
        /// <param name="alist"></param>
        public void SearchData(ArrayList alist)
        {
            for (int i = 0; i < alist.Count; i++)
            {
            }

            foreach (object val in alist)
            {
            }

            //通过枚举器、迭代器遍历，foreach的底层就是枚举器，也不能里面修改集合
            IEnumerator ie = alist.GetEnumerator();  //一开始ie没有指向，需要movenext才开始指向第一位
            while (ie.MoveNext())
            {
                var val = ie.Current;
            }
        }

        /// <summary>
        /// 集合ArrayList的其他方法
        /// </summary>
        /// <param name="alist"></param>
        public void OtherFun(ArrayList alist)
        {
            //排序
            alist.Sort();     //顺序排序
            alist.Reverse();  //倒叙排序
             
            //拷贝
            object[] obj = new object[10];
            alist.CopyTo(obj);
        }