C# System.Collections.Generic.Dictionary

  1 using System;
  2 using System.Collections.Generic;
  3 
  4 public class Example
  5 {
  6     public static void Main()
  7     {
  8         // Create a new dictionary of strings, with string keys.
  9         //
 10         Dictionary<string, string> openWith = 
 11             new Dictionary<string, string>();
 12 
 13         // Add some elements to the dictionary. There are no 
 14         // duplicate keys, but some of the values are duplicates.
 15         openWith.Add("txt", "notepad.exe");
 16         openWith.Add("bmp", "paint.exe");
 17         openWith.Add("dib", "paint.exe");
 18         openWith.Add("rtf", "wordpad.exe");
 19 
 20         // The Add method throws an exception if the new key is 
 21         // already in the dictionary.
 22         try
 23         {
 24             openWith.Add("txt", "winword.exe");
 25         }
 26         catch (ArgumentException)
 27         {
 28             Console.WriteLine("An element with Key = \"txt\" already exists.");
 29         }
 30 
 31         // The Item property is another name for the indexer, so you 
 32         // can omit its name when accessing elements. 
 33         Console.WriteLine("For key = \"rtf\", value = {0}.", 
 34             openWith["rtf"]);
 35 
 36         // The indexer can be used to change the value associated
 37         // with a key.
 38         openWith["rtf"] = "winword.exe";
 39         Console.WriteLine("For key = \"rtf\", value = {0}.", 
 40             openWith["rtf"]);
 41 
 42         // If a key does not exist, setting the indexer for that key
 43         // adds a new key/value pair.
 44         openWith["doc"] = "winword.exe";
 45 
 46         // The indexer throws an exception if the requested key is
 47         // not in the dictionary.
 48         try
 49         {
 50             Console.WriteLine("For key = \"tif\", value = {0}.", 
 51                 openWith["tif"]);
 52         }
 53         catch (KeyNotFoundException)
 54         {
 55             Console.WriteLine("Key = \"tif\" is not found.");
 56         }
 57 
 58         // When a program often has to try keys that turn out not to
 59         // be in the dictionary, TryGetValue can be a more efficient 
 60         // way to retrieve values.
 61         string value = "";
 62         if (openWith.TryGetValue("tif", out value))
 63         {
 64             Console.WriteLine("For key = \"tif\", value = {0}.", value);
 65         }
 66         else
 67         {
 68             Console.WriteLine("Key = \"tif\" is not found.");
 69         }
 70 
 71         // ContainsKey can be used to test keys before inserting 
 72         // them.
 73         if (!openWith.ContainsKey("ht"))
 74         {
 75             openWith.Add("ht", "hypertrm.exe");
 76             Console.WriteLine("Value added for key = \"ht\": {0}", 
 77                 openWith["ht"]);
 78         }
 79 
 80         // When you use foreach to enumerate dictionary elements,
 81         // the elements are retrieved as KeyValuePair objects.
 82         Console.WriteLine();
 83         foreach( KeyValuePair<string, string> kvp in openWith )
 84         {
 85             Console.WriteLine("Key = {0}, Value = {1}", 
 86                 kvp.Key, kvp.Value);
 87         }
 88 
 89         // To get the values alone, use the Values property.
 90         Dictionary<string, string>.ValueCollection valueColl =
 91             openWith.Values;
 92 
 93         // The elements of the ValueCollection are strongly typed
 94         // with the type that was specified for dictionary values.
 95         Console.WriteLine();
 96         foreach( string s in valueColl )
 97         {
 98             Console.WriteLine("Value = {0}", s);
 99         }
100 
101         // To get the keys alone, use the Keys property.
102         Dictionary<string, string>.KeyCollection keyColl =
103             openWith.Keys;
104 
105         // The elements of the KeyCollection are strongly typed
106         // with the type that was specified for dictionary keys.
107         Console.WriteLine();
108         foreach( string s in keyColl )
109         {
110             Console.WriteLine("Key = {0}", s);
111         }
112 
113         // Use the Remove method to remove a key/value pair.
114         Console.WriteLine("\nRemove(\"doc\")");
115         openWith.Remove("doc");
116 
117         if (!openWith.ContainsKey("doc"))
118         {
119             Console.WriteLine("Key \"doc\" is not found.");
120         }
121     }
122 }
123 
124 /* This code example produces the following output:
125 
126 An element with Key = "txt" already exists.
127 For key = "rtf", value = wordpad.exe.
128 For key = "rtf", value = winword.exe.
129 Key = "tif" is not found.
130 Key = "tif" is not found.
131 Value added for key = "ht": hypertrm.exe
132 
133 Key = txt, Value = notepad.exe
134 Key = bmp, Value = paint.exe
135 Key = dib, Value = paint.exe
136 Key = rtf, Value = winword.exe
137 Key = doc, Value = winword.exe
138 Key = ht, Value = hypertrm.exe
139 
140 Value = notepad.exe
141 Value = paint.exe
142 Value = paint.exe
143 Value = winword.exe
144 Value = winword.exe
145 Value = hypertrm.exe
146 
147 Key = txt
148 Key = bmp
149 Key = dib
150 Key = rtf
151 Key = doc
152 Key = ht
153 
154 Remove("doc")
155 Key "doc" is not found.
156  */

 1 using System;
 2 using System.Collections.Generic;
 3 public class Example
 4 {
 5          public static void Main()
 6          {
 7                //一、创建泛型哈希表，然后加入元素
 8                Dictionary<string, string> oscar = new Dictionary<string, string>();
 9                oscar.Add("哈莉?贝瑞", "《死囚之舞》");
10                oscar.Add("朱迪?丹奇", "《携手人生》");
11                oscar.Add("尼科尔?基德曼", "《红磨坊》");
12                oscar.Add("詹妮弗?康纳利", "《美丽心灵》");
13                oscar.Add("蕾妮?齐维格", "《BJ单身日记》");
14 
15                //二、删除元素
16                oscar.Remove("詹妮弗?康纳利");
17 
18                //三、假如不存在元素则加入元素
19                if (!oscar.ContainsKey("茜茜?斯派克")) oscar.Add("茜茜?斯派克", "《不伦之恋》");
20                
21 
22                //四、显然容量和元素个数
23                Console.WriteLine("元素个数: {0}", oscar.Count);
24 
25                //五、遍历集合
26                Console.WriteLine("74届奥斯卡最佳女主角及其电影：");
27                foreach (KeyValuePair<string, string> kvp in oscar)
28                {
29                       Console.WriteLine("姓名：{0},电影：{1}", kvp.Key, kvp.Value);
30                }
31 
32               //六、得到哈希表中键的集合
33               Dictionary<string, string>.KeyCollection keyColl = oscar.Keys;
34               //遍历键的集合
35               Console.WriteLine("最佳女主角：");
36               foreach (string s in keyColl)
37               {
38                    Console.WriteLine(s);
39               }
40 
41               //七、得到哈希表值的集合
42               Dictionary<string, string>.ValueCollection valueColl = oscar.Values;
43               //遍历值的集合
44               Console.WriteLine("最佳女主角电影：");
45               foreach (string s in valueColl)
46               {
47                    Console.WriteLine(s);
48               }
49 
50               //八、使用TryGetValue方法获取指定键对应的值
51               string slove = string.Empty;
52               if (oscar.TryGetValue("朱迪?丹奇", out slove))
53                      Console.WriteLine("我最喜欢朱迪?丹奇的电影{0}", slove);
54               else
55                      Console.WriteLine("没找到朱迪?丹奇的电影");
56 
57               //九、清空哈希表
58               oscar.Clear();
59               Console.ReadLine();
60        }
61 }

 1 //定义字典
 2                 Dictionary<string, string> d = new Dictionary<string, string>();
 3 
 4                 //添加字典的元素
 5                 for (int i = 0; i < 5; i++)
 6                 {
 7                     d.Add("key" + i, "value" + i);
 8                 }
 9 
10                 //取值/赋值
11                 string val = d["key1"];
12                 d["key1"] = "new value";
13 
14                 //遍历key
15                 foreach (string key in d.Keys)
16                 {
17                     Console.WriteLine("Key = {0}", key);
18                 }
19                 //遍历value
20                 foreach (string v in d.Values)
21                 {
22                     Console.WriteLine("value = {0}", v);
23                 }
24 
25                 //遍历value, Second Method
26                 Dictionary<string, string>.ValueCollection valueColl = d.Values;
27                 foreach (string s in valueColl)
28                 {
29                     Console.WriteLine("Second Method, Value = {0}", s);
30                 }
31 
32                 //遍历字典
33                 foreach (KeyValuePair<string, string> kvp in d)
34                 {
35                     Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
36                 }
37                 //删除元素
38                 d.Remove("key1");
39                 if (!d.ContainsKey("key1"))
40                 {
41                     Console.WriteLine("Key \"key1\" is not found.");
42                 }
43                 //判断键存在
44                 if (d.ContainsKey("key1")) // True 
45                 {
46                     Console.WriteLine("An element with Key = \"key1\" exists.");
47                 }

构造函数 

属性 

方法