Dictionary的遍历和修改

最新推荐文章于 2023-12-07 21:51:53 发布

转载最新推荐文章于 2023-12-07 21:51:53 发布 · 219 阅读

本文介绍了一种在C#中高效操作Dictionary的方法，通过不同的遍历方式来修改字典的内容，并展示了foreach遍历与使用Keys属性进行遍历的区别。

        /// <summary>
        /// 初始化一个Dic
        /// </summary>
        public static void mainTest()
        {
            Dictionary<String, Int32> dic = new Dictionary<String, Int32>();
            dic.Add("1", 1);
            dic.Add("2", 2);
            dic.Add("3", 3);

            Console.WriteLine("Org=============");
            foreachTravelDic(dic);

            modifyDic1(dic);
            Console.WriteLine("modify1=============");
            foreachTravelDic(dic);


            modifyDic2(dic);
            Console.WriteLine("modify2=============");
            foreachTravelDic(dic);

            Console.ReadKey();
        }

        /// <summary>
        /// foreach遍历Dictionary
        /// </summary>
        /// <param name="dic"></param>
        public static void foreachTravelDic(Dictionary<String, Int32> dic)
        {
            foreach (KeyValuePair<String, Int32> kvp in dic)
            {
                Console.WriteLine(String.Format("Key:{0}; Value:{1}", kvp.Key, kvp.Value));
                //dic[kvp.Key] = 2;//此操作会报错
            }
        }


        /// <summary>
        ///使用dic.Keys.ToArray方法遍历时更改Dic
        /// </summary>
        /// <param name="dic"></param>
        private static void modifyDic2(Dictionary<String, Int32> dic)
        {
            String[] keyStr = dic.Keys.ToArray<String>();
            for (int i = 0; i < keyStr.Length; i++)
            {
                dic[keyStr[i]] = dic[keyStr[i]] + 22;
            }
        }

        /// <summary>
        /// 使用dic.Keys.CopyTo方法遍历时更改Dic
        /// </summary>
        /// <param name="dic"></param>
        private static void modifyDic1(Dictionary<String, Int32> dic)
        {
            int dicCount = dic.Keys.Count;
            String[] strKey = new String[dicCount];
            dic.Keys.CopyTo(strKey, 0);//支持.net2.0
            for (int i = 0; i < strKey.Length; i++)
            {
                if (dic.ContainsKey(strKey[i]))
                {
                    dic[strKey[i]] = dic[strKey[i]] + 11;
                }
            }
        }

output:

Org=============
Key:1; Value:1
Key:2; Value:2
Key:3; Value:3
modify1=============
Key:1; Value:12
Key:2; Value:13
Key:3; Value:14
modify2=============
Key:1; Value:34
Key:2; Value:35
Key:3; Value:36