Dictionary通过下标获取key和value

            http://www.cnblogs.com/dyllove98/archive/2013/06/08/3127443.html

            Dictionary<int, string> dic = new Dictionary<int, string>();

            Dictionary<int, string>.Enumerator en = dic.GetEnumerator();
            for (int i = 0; i < dic.Count; i++)
            {
                if (en.MoveNext())
                {
                    int key = en.Current.Key;
                    string value = en.Current.Value;
                }
            }