C# System.Collections.Generic.Dictionary

using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create a new dictionary of strings, with string keys.
        //
        Dictionary<string, string> openWith = 
            new Dictionary<string, string>();

        // Add some elements to the dictionary. 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 dictionary.
        try
        {
            openWith.Add("txt", "winword.exe");
        }
        catch (ArgumentException)
        {
            Console.WriteLine("An element with Key = "txt" already exists.");
        }

        // The Item property is another name for the indexer, so you 
        // can omit its name when accessing elements. 
        Console.WriteLine("For key = "rtf", value = {0}.", 
            openWith["rtf"]);

        // The indexer 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 indexer for that key
        // adds a new key/value pair.
        openWith["doc"] = "winword.exe";

        // The indexer throws an exception if the requested key is
        // not in the dictionary.
        try
        {
            Console.WriteLine("For key = "tif", value = {0}.", 
                openWith["tif"]);
        }
        catch (KeyNotFoundException)
        {
            Console.WriteLine("Key = "tif" is not found.");
        }

        // When a program often has to try keys that turn out not to
        // be in the dictionary, TryGetValue can be a more efficient 
        // way to retrieve values.
        string value = "";
        if (openWith.TryGetValue("tif", out value))
        {
            Console.WriteLine("For key = "tif", value = {0}.", value);
        }
        else
        {
            Console.WriteLine("Key = "tif" is not found.");
        }

        // 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 dictionary elements,
        // the elements are retrieved as KeyValuePair objects.
        Console.WriteLine();
        foreach( KeyValuePair<string, string> kvp in openWith )
        {
            Console.WriteLine("Key = {0}, Value = {1}", 
                kvp.Key, kvp.Value);
        }

        // To get the values alone, use the Values property.
        Dictionary<string, string>.ValueCollection valueColl =
            openWith.Values;

        // The elements of the ValueCollection are strongly typed
        // with the type that was specified for dictionary values.
        Console.WriteLine();
        foreach( string s in valueColl )
        {
            Console.WriteLine("Value = {0}", s);
        }

        // To get the keys alone, use the Keys property.
        Dictionary<string, string>.KeyCollection keyColl =
            openWith.Keys;

        // The elements of the KeyCollection are strongly typed
        // with the type that was specified for dictionary 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("
Remove("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.
Key = "tif" is not found.
Key = "tif" is not found.
Value added for key = "ht": hypertrm.exe

Key = txt, Value = notepad.exe
Key = bmp, Value = paint.exe
Key = dib, Value = paint.exe
Key = rtf, Value = winword.exe
Key = doc, Value = winword.exe
Key = ht, Value = hypertrm.exe

Value = notepad.exe
Value = paint.exe
Value = paint.exe
Value = winword.exe
Value = winword.exe
Value = hypertrm.exe

Key = txt
Key = bmp
Key = dib
Key = rtf
Key = doc
Key = ht

Remove("doc")
Key "doc" is not found.
 */

using System;
using System.Collections.Generic;
public class Example
{
         public static void Main()
         {
               //一、创建泛型哈希表，然后加入元素
               Dictionary<string, string> oscar = new Dictionary<string, string>();
               oscar.Add("哈莉?贝瑞", "《死囚之舞》");
               oscar.Add("朱迪?丹奇", "《携手人生》");
               oscar.Add("尼科尔?基德曼", "《红磨坊》");
               oscar.Add("詹妮弗?康纳利", "《美丽心灵》");
               oscar.Add("蕾妮?齐维格", "《BJ单身日记》");

               //二、删除元素
               oscar.Remove("詹妮弗?康纳利");

               //三、假如不存在元素则加入元素
               if (!oscar.ContainsKey("茜茜?斯派克")) oscar.Add("茜茜?斯派克", "《不伦之恋》");
               

               //四、显然容量和元素个数
               Console.WriteLine("元素个数: {0}", oscar.Count);

               //五、遍历集合
               Console.WriteLine("74届奥斯卡最佳女主角及其电影：");
               foreach (KeyValuePair<string, string> kvp in oscar)
               {
                      Console.WriteLine("姓名：{0},电影：{1}", kvp.Key, kvp.Value);
               }

              //六、得到哈希表中键的集合
              Dictionary<string, string>.KeyCollection keyColl = oscar.Keys;
              //遍历键的集合
              Console.WriteLine("最佳女主角：");
              foreach (string s in keyColl)
              {
                   Console.WriteLine(s);
              }

              //七、得到哈希表值的集合
              Dictionary<string, string>.ValueCollection valueColl = oscar.Values;
              //遍历值的集合
              Console.WriteLine("最佳女主角电影：");
              foreach (string s in valueColl)
              {
                   Console.WriteLine(s);
              }

              //八、使用TryGetValue方法获取指定键对应的值
              string slove = string.Empty;
              if (oscar.TryGetValue("朱迪?丹奇", out slove))
                     Console.WriteLine("我最喜欢朱迪?丹奇的电影{0}", slove);
              else
                     Console.WriteLine("没找到朱迪?丹奇的电影");

              //九、清空哈希表
              oscar.Clear();
              Console.ReadLine();
       }
}

//定义字典
                Dictionary<string, string> d = new Dictionary<string, string>();

                //添加字典的元素
                for (int i = 0; i < 5; i++)
                {
                    d.Add("key" + i, "value" + i);
                }

                //取值/赋值
                string val = d["key1"];
                d["key1"] = "new value";

                //遍历key
                foreach (string key in d.Keys)
                {
                    Console.WriteLine("Key = {0}", key);
                }
                //遍历value
                foreach (string v in d.Values)
                {
                    Console.WriteLine("value = {0}", v);
                }

                //遍历value, Second Method
                Dictionary<string, string>.ValueCollection valueColl = d.Values;
                foreach (string s in valueColl)
                {
                    Console.WriteLine("Second Method, Value = {0}", s);
                }

                //遍历字典
                foreach (KeyValuePair<string, string> kvp in d)
                {
                    Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
                }
                //删除元素
                d.Remove("key1");
                if (!d.ContainsKey("key1"))
                {
                    Console.WriteLine("Key "key1" is not found.");
                }
                //判断键存在
                if (d.ContainsKey("key1")) // True 
                {
                    Console.WriteLine("An element with Key = "key1" exists.");
                }

构造函数 

Dictionary<TKey,TValue>()	初始化 Dictionary<TKey,TValue> 类的新实例，该实例为空且具有默认的初始容量，并使用键类型的默认相等比较器。
Dictionary<TKey,TValue>(IDictionary<TKey,TValue>)	初始化 Dictionary<TKey,TValue> 类的新实例，该实例包含从指定的 IDictionary<TKey,TValue> 中复制的元素并为键类型使用默认的相等比较器。
Dictionary<TKey,TValue>(IDictionary<TKey,TValue>, IEqualityComparer<TKey>)	初始化 Dictionary<TKey,TValue> 类的新实例，该实例包含从指定的 IDictionary<TKey,TValue> 中复制的元素并使用指定的 IEqualityComparer<T>。
Dictionary<TKey,TValue>(IEqualityComparer<TKey>)	初始化 Dictionary<TKey,TValue> 类的新实例，该实例为空且具有默认的初始容量，并使用指定的 IEqualityComparer<T>。
Dictionary<TKey,TValue>(Int32)	初始化 Dictionary<TKey,TValue> 类的新实例，该实例为空且具有指定的初始容量，并为键类型使用默认的相等比较器。
Dictionary<TKey,TValue>(Int32, IEqualityComparer<TKey>)	初始化 Dictionary<TKey,TValue> 类的新实例，该实例为空且具有指定的初始容量，并使用指定的 IEqualityComparer<T>。
Dictionary<TKey,TValue>(SerializationInfo, StreamingContext)	用序列化数据初始化 Dictionary<TKey,TValue> 类的新实例。

属性 

Comparer	获取用于确定字典中的键是否相等的 IEqualityComparer<T>。
Count	获取包含在 Dictionary<TKey,TValue> 中的键/值对的数目。
Item[TKey]	获取或设置与指定的键关联的值。
Keys	获取包含 Dictionary<TKey,TValue> 中的键的集合。
Values	获取包含 Dictionary<TKey,TValue> 中的值的集合。

方法 

Add(TKey, TValue)	将指定的键和值添加到字典中。
Clear()	将所有键和值从 Dictionary<TKey,TValue> 中移除。
ContainsKey(TKey)	确定是否 Dictionary<TKey,TValue> 包含指定键。
ContainsValue(TValue)	确定 Dictionary<TKey,TValue> 是否包含特定值。
Equals(Object)	确定指定的对象是否等于当前对象。 (Inherited from Object)
GetEnumerator()	返回循环访问 Dictionary<TKey,TValue> 的枚举数。
GetHashCode()	作为默认哈希函数。 (Inherited from Object)
GetObjectData(SerializationInfo, StreamingContext)	实现 ISerializable 接口，并返回序列化 Dictionary<TKey,TValue> 实例所需的数据。
GetType()	获取当前实例的 Type。 (Inherited from Object)
MemberwiseClone()	创建当前 Object 的浅表副本。 (Inherited from Object)
OnDeserialization(Object)	实现 ISerializable 接口，并在完成反序列化之后引发反序列化事件。
Remove(TKey)	从 Dictionary<TKey,TValue> 中移除所指定的键的值。
ToString()	返回表示当前对象的字符串。 (Inherited from Object)
TryGetValue(TKey, TValue)	获取与指定键关联的值。