C# NameValueCollection集合 (轉(zhuǎn))

1.NameValueCollection類集合是基于?NameObjectCollectionBase?類。

但與 NameObjectCollectionBase 不同，該類在一個鍵下存儲多個字符串值（就是鍵相同，值就連接起來如下例子）。該類可用于標(biāo)頭、查詢字符串和窗體數(shù)據(jù)。
每個元素都是一個鍵/值對。NameValueCollection 的容量是 NameValueCollection 可以保存的元素數(shù)。
NameValueCollection 的默認(rèn)初始容量為零。隨著向 NameValueCollection 中添加元素，容量通過重新分配按需自動增加。
如下例子：

NameValueCollection myCol = new NameValueCollection(); myCol.Add("red", "rojo");//如果鍵值red相同結(jié)果合并 rojo,rouge myCol.Add("green", "verde"); myCol.Add("blue", "azul"); myCol.Add("red", "rouge");

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2.NameValueCollection與Hashtable的區(qū)別

a.引用區(qū)別

hashtable:using System.Collections;

NameValueCollection:using System.Collections.Specialized;?

b.鍵是否重復(fù)

NameValueCollection:允許重復(fù).

HashTable是鍵-值集合,但鍵不能出現(xiàn)重復(fù).?

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Hashtable?ht?=?new?Hashtable();??

ht.Add("key","value");??

ht.Add("key",?"value1");?//出錯??

ht["key"]?=?"value1";?//正確??

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3.初始化NameValueCollection?

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初始化NameValueCollection需引用using System.Collections.Specialized;
完整例子源碼：

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using?System;? using?System.Collections;??

using?System.Collections.Specialized;??

??

namespace?SamplesNameValueCollection??

{??

????class?Program??

????{??

??

????????public?static?void?Main()??

????????{??

????????????//初始化NameValueCollection需引用using?System.Collections.Specialized;??

????????????NameValueCollection?myCol?=?new?NameValueCollection();??

????????????myCol.Add("red",?"rojo");//如果鍵值red相同結(jié)果合并?rojo,rouge??

????????????myCol.Add("green",?"verde");??

????????????myCol.Add("blue",?"azul");??

????????????myCol.Add("red",?"rouge");??

??

????????????//?Displays?the?values?in?the?NameValueCollection?in?two?different?ways.??

????????????//顯示鍵，值??

????????????Console.WriteLine("Displays?the?elements?using?the?AllKeys?property?and?the?Item?(indexer)?property:");??

????????????PrintKeysAndValues(myCol);??

????????????Console.WriteLine("Displays?the?elements?using?GetKey?and?Get:");??

????????????PrintKeysAndValues2(myCol);??

??

????????????//?Gets?a?value?either?by?index?or?by?key.??

????????????//按索引或值獲取??

????????????Console.WriteLine("Index?1?contains?the?value?{0}.",?myCol[1]);//索引1的值??

????????????Console.WriteLine("Key?/"red/"?has?the?value?{0}.",?myCol["red"]);//鍵為red的對應(yīng)值rouge??

????????????Console.WriteLine();??

??

????????????//?Copies?the?values?to?a?string?array?and?displays?the?string?array.??

????????????String[]?myStrArr?=?new?String[myCol.Count];??

????????????myCol.CopyTo(myStrArr,?0);??

????????????Console.WriteLine("The?string?array?contains:");??

????????????foreach?(String?s?in?myStrArr)??

????????????????Console.WriteLine("???{0}",?s);??

????????????Console.WriteLine();??

??

????????????//查找green鍵值然后刪除??

????????????myCol.Remove("green");??

????????????Console.WriteLine("The?collection?contains?the?following?elements?after?removing?/"green/":");??

????????????PrintKeysAndValues(myCol);??

??

????????????//清空集合??

????????????myCol.Clear();??

????????????Console.WriteLine("The?collection?contains?the?following?elements?after?it?is?cleared:");??

????????????PrintKeysAndValues(myCol);??

??

????????}??

????????//顯示鍵，值??

????????public?static?void?PrintKeysAndValues(NameValueCollection?myCol)??

????????{??

????????????IEnumerator?myEnumerator?=?myCol.GetEnumerator();??

????????????Console.WriteLine("???KEY????????VALUE");??

????????????foreach?(String?s?in?myCol.AllKeys)??

????????????????Console.WriteLine("???{0,-10}?{1}",?s,?myCol[s]);??

????????????Console.WriteLine();??

????????}??

????????//顯示索引,?鍵,值??

????????public?static?void?PrintKeysAndValues2(NameValueCollection?myCol)??

????????{??

????????????Console.WriteLine("???[INDEX]?KEY????????VALUE");??

????????????for?(int?i?=?0;?i?<?myCol.Count;?i++)??

????????????????Console.WriteLine("???[{0}]?????{1,-10}?{2}",?i,?myCol.GetKey(i),?myCol.Get(i));??

????????????Console.WriteLine();??

????????}??

????}??

??

}??

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4.NameValueCollection遍歷?

與Hashtable相似:?

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NameValueCollection?myCol?=?new?NameValueCollection();????

myCol.Add("red",?"rojo");//如果鍵值red相同結(jié)果合并?rojo,rouge????

myCol.Add("green",?"verde");????

myCol.Add("blue",?"azul");??

myCol["red"]?=?"dd";??

??

foreach?(string?key?in?myCol.Keys)??

{??

????Console.WriteLine("{0}:{1}",?key,?myCol[key]);??

}??

Console.ReadLine();??

轉(zhuǎn)自：http://blog.csdn.net/a497785609/article/details/5702356

posted on 2013-08-20 14:09 天使半只翼 閱讀(...) 評論(...) 編輯 收藏

轉(zhuǎn)載于:https://www.cnblogs.com/william-lin/p/3270092.html

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