C＃|获取包含HybridDictionary中的键的ICollection

HybridDictionary.Keys属性用于获取包含HybridDictionary中的键的ICollection。

句法：

public System.Collections.ICollection Keys { get; }

返回值：返回包含HybridDictionary中的键的ICollection。

下面的程序说明了HybridDictionary.Keys属性的用法：

范例1：

// C# code to get an ICollection containing
// the keys in the HybridDictionary.
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a HybridDictionary named myDict
        HybridDictionary myDict = new HybridDictionary();
  
        // Adding key/value pairs in myDict
        myDict.Add("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");
        myDict.Add("E", "Elephant");
        myDict.Add("F", "Fish");
  
        // Creating a String arr named myArr
        String[] myArr = new String[myDict.Count];
  
        // copying the Keys in HybridDictionary
        // to a one-dimensional Array instance
        // at the specified index.
        myDict.Keys.CopyTo(myArr, 0);
  
        // To get an ICollection containing
        // the keys in the HybridDictionary
        for (int i = 0; i < myDict.Count; i++)
            Console.WriteLine(myArr[i]);
    }
}

输出：

A
B
C
D
E
F

范例2：

// C# code to get an ICollection containing
// the keys in the HybridDictionary.
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a HybridDictionary named myDict
        HybridDictionary myDict = new HybridDictionary();
  
        // Adding key/value pairs in myDict
        myDict.Add("I", "first");
        myDict.Add("II", "second");
        myDict.Add("III", "third");
        myDict.Add("IV", "fourth");
        myDict.Add("V", "fifth");
  
        // Creating a String arr named myArr
        String[] myArr = new String[myDict.Count];
  
        // copying the Keys in HybridDictionary
        // to a one-dimensional Array instance
        // at the specified index.
        myDict.Keys.CopyTo(myArr, 0);
  
        // To get an ICollection containing
        // the keys in the HybridDictionary
        for (int i = 0; i < myDict.Count; i++)
            Console.WriteLine(myArr[i]);
    }
}

输出：

I
II
III
IV
V

笔记：

• ICollection中值的顺序未指定，但与Values方法返回的ICollection中关联值的顺序相同。
• 返回的ICollection不是静态副本。而是，ICollection引用了原始HybridDictionary中的键。因此，对HybridDictionary的更改将继续反映在ICollection中。
• 检索此属性的值是O(1)操作。

参考：

• https://docs.microsoft.com/zh-cn/dotnet/api/system.collections.specialized.hybriddictionary.keys?view=netframework-4.7.2