1. To use the Dictionary collection, you need to import the C# generic namespace
System.Collections.Generic //程序集:mscorlib
A mapping from a set of keys (Key) to a set of values (Value). Each added item consists of a value and its related The key composition of the connection
Any key must be unique
The key cannot be a null reference null (Nothing in VB). If the value is a reference type, it can be a null value
Key and Value can be of any type (string, int, custom class, etc.)
Create and initialize
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Dictionary<int,string> myDictionary=new Dictionary<int,string>();
Add elements
myDictionary.Add(1,"C#"); myDictionary.Add(2,"C++"); myDictionary.Add(3,"ASP.NET"); myDictionary.Add(4,"MVC");
Find elements by Key
if(myDictionary.ContainsKey(1)) { Console.WriteLine("Key:{0},Value:{1}","1", myDictionary[1]); }
Traverse elements by KeyValuePair
foreach(KeyValuePair<int,string> kvp in myDictionary) { Console.WriteLine("Key = {0}, Value = {1}",kvp.Key, kvp.Value); }
Only traverse the key Keys attribute
Dictionary<int,string>.KeyCollection keyCol = myDictionary.Keys;foreach(intkeyinkeyCol) { Console.WriteLine("Key = {0}", key); }
Only traverse the value Valus attribute
Dictionary<int,string>.ValueCollection valueCol = myDictionary.Values;foreach(stringvalueinvalueCol) { Console.WriteLine("Value = {0}", value); }
Remove the specified key value through the Remove method
myDictionary.Remove(1);if(myDictionary.ContainsKey(1)) { Console.WriteLine("Key:{0},Value:{1}","1", myDictionary[1]); }else{ Console.WriteLine("不存在 Key : 1"); }
Explanations of other common properties and methods:
Comparer: // 获取用于确定字典中的键是否相等的 IEqualityComparer。 Count: // 获取包含在 Dictionary中的键/值对的数目。 Item: //获取或设置与指定的键相关联的值。 Keys: // 获取包含 Dictionary中的键的集合。 Values: // 获取包含 Dictionary中的值的集合。 Add: // 将指定的键和值添加到字典中。 Clear: //从 Dictionary中移除所有的键和值。 ContainsKey: //确定 Dictionary是否包含指定的键。 ContainsValue: //确定 Dictionary是否包含特定值。 GetEnumerator: // 返回循环访问 Dictionary的枚举数。 GetType: // 获取当前实例的 Type。 (从 Object 继承。) Remove: //从 Dictionary中移除所指定的键的值。 ToString: //返回表示当前 Object的 String。 (从 Object 继承。) TryGetValue: //获取与指定的键相关联的值。
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