删除Dictionary中键对应的元素，删除后再次访问会报错。如果删除一个不存在的元素将返回flase。
操作示例：
另一种方法：
int value = 0; bool result = dict.Remove("2", out value); // 如果dict 里包含键为“2”的元素，则result 为 false且value为对应的值 1.4.3 不常用但有用的方法
ContainsValue()
是否包含值，与ContainsKey的用法一样，只不过遍历的是值；用处不大。
Values
获取值的集合类似与KeyValues。
2. 传统集合（非泛型）C#的传统集合基本都存放在System.Collections命名空间里，详细的可以查看微软官方文档。这个命名空间里的集合类使用都不多，不过C#的集合体系的接口规范都是在这个里面定义的。
2.1 常见类介绍
ArrayList List的非泛型版，与List操作方法一致，不过返回值是Object类型
SortedList 一个排序的键值对集合，我没用过，不过官方给了如下示例：
using System; using System.Collections; public class SamplesSortedList { public static void Main() { // Creates and initializes a new SortedList. SortedList mySL = new SortedList(); mySL.Add("Third", "!"); mySL.Add("Second", "World"); mySL.Add("First", "Hello"); // Displays the properties and values of the SortedList. Console.WriteLine( "mySL" ); Console.WriteLine( " Count: {0}", mySL.Count ); Console.WriteLine( " Capacity: {0}", mySL.Capacity ); Console.WriteLine( " Keys and Values:" ); PrintKeysAndValues( mySL ); } public static void PrintKeysAndValues( SortedList myList ) { Console.WriteLine( "\t-KEY-\t-VALUE-" ); for ( int i = 0; i < myList.Count; i++ ) { Console.WriteLine( "\t{0}:\t{1}", myList.GetKey(i), myList.GetByIndex(i) ); } Console.WriteLine(); } }
HashTable表示根据键的哈希代码进行组织的键/值对的集合。HashTable的结构类似于Dictionary但又与其不同，它的键值存储用的是Hash值。以下是官方给出的示例代码：
using System; using System.Collections; class Example { public static void Main() { // Create a new hash table. // Hashtable openWith = new Hashtable(); // Add some elements to the hash table. There are no // duplicate keys, but some of the values are duplicates. openWith.Add("txt", "notepad.exe"); openWith.Add("bmp", "paint.exe"); openWith.Add("dib", "paint.exe"); openWith.Add("rtf", "wordpad.exe"); // The Add method throws an exception if the new key is // already in the hash table. try { openWith.Add("txt", "winword.exe"); } catch { Console.WriteLine("An element with Key = \"txt\" already exists."); } // The Item property is the default property, so you // can omit its name when accessing elements. Console.WriteLine("For key = \"rtf\", value = {0}.", openWith["rtf"]); // The default Item property can be used to change the value // associated with a key. openWith["rtf"] = "winword.exe"; Console.WriteLine("For key = \"rtf\", value = {0}.", openWith["rtf"]); // If a key does not exist, setting the default Item property // for that key adds a new key/value pair. openWith["doc"] = "winword.exe"; // ContainsKey can be used to test keys before inserting // them. if (!openWith.ContainsKey("ht")) { openWith.Add("ht", "hypertrm.exe"); Console.WriteLine("Value added for key = \"ht\": {0}", openWith["ht"]); } // When you use foreach to enumerate hash table elements, // the elements are retrieved as KeyValuePair objects. Console.WriteLine(); foreach( DictionaryEntry de in openWith ) { Console.WriteLine("Key = {0}, Value = {1}", de.Key, de.Value); } // To get the values alone, use the Values property. ICollection valueColl = openWith.Values; // The elements of the ValueCollection are strongly typed // with the type that was specified for hash table values. Console.WriteLine(); foreach( string s in valueColl ) { Console.WriteLine("Value = {0}", s); } // To get the keys alone, use the Keys property. ICollection keyColl = openWith.Keys; // The elements of the KeyCollection are strongly typed // with the type that was specified for hash table keys. Console.WriteLine(); foreach( string s in keyColl ) { Console.WriteLine("Key = {0}", s); } // Use the Remove method to remove a key/value pair. Console.WriteLine("\nRemove(\"doc\")"); openWith.Remove("doc"); if (!openWith.ContainsKey("doc")) { Console.WriteLine("Key \"doc\" is not found."); } } } /* This code example produces the following output: An element with Key = "txt" already exists. For key = "rtf", value = wordpad.exe. For key = "rtf", value = winword.exe. Value added for key = "ht": hypertrm.exe Key = dib, Value = paint.exe Key = txt, Value = notepad.exe Key = ht, Value = hypertrm.exe Key = bmp, Value = paint.exe Key = rtf, Value = winword.exe Key = doc, Value = winword.exe Value = paint.exe Value = notepad.exe Value = hypertrm.exe Value = paint.exe Value = winword.exe Value = winword.exe Key = dib Key = txt Key = ht Key = bmp Key = rtf Key = doc Remove("doc") Key "doc" is not found. */虽然C#框架保留了非泛型集合元素，但不建议使用非泛型集合进行开发。
3 一些不常用的集合类除了之前所说的几个集合类，C#还设置了一些在开发中不常用但在特定场合很有用的集合类。
3.1 Queue<T> 和 Queue