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C# | Get an ICollection containing the keys in ListDictionary

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ListDictionary.Keys property is used to get an ICollection containing the keys in the ListDictionary. Syntax:
public System.Collections.ICollection Keys { get; }
Return Value : It returns an ICollection containing the keys in the ListDictionary. Below are the programs to illustrate the use of ListDictionary.Keys property: Example 1:
// C# code to get an ICollection
// containing the keys in the ListDictionary
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a ListDictionary named myDict
        ListDictionary myDict = new ListDictionary();
  
        myDict.Add("Australia", "Canberra");
        myDict.Add("Belgium", "Brussels");
        myDict.Add("Netherlands", "Amsterdam");
        myDict.Add("China", "Beijing");
        myDict.Add("Russia", "Moscow");
        myDict.Add("India", "New Delhi");
  
        // Get an ICollection containing
        // the keys in the ListDictionary
        ICollection ic = myDict.Keys;
  
        // Displaying the keys in ICollection ic
        foreach(String str in ic)
        {
            Console.WriteLine(str);
        }
    }
}

                    
Output:
Australia
Belgium
Netherlands
China
Russia
India
Example 2:
// C# code to get an ICollection
// containing the keys in the ListDictionary
using System;
using System.Collections;
using System.Collections.Specialized;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a ListDictionary named myDict
        ListDictionary myDict = new ListDictionary();
  
        myDict.Add("I", "first");
        myDict.Add("II", "second");
        myDict.Add("III", "third");
        myDict.Add("IV", "fourth");
        myDict.Add("V", "fifth");
  
        // Get an ICollection containing
        // the keys in the ListDictionary
        ICollection ic = myDict.Keys;
  
        // Displaying the keys in ICollection ic
        foreach(String str in ic)
        {
            Console.WriteLine(str);
        }
    }
}

                    
Output:
I
II
III
IV
V
Note:
  • The order of the values in the ICollection is unspecified, but it is the same order as the associated values in the ICollection returned by the Values method.
  • The returned ICollection is not a static copy. Instead, the ICollection refers back to the keys in the original ListDictionary. Therefore, changes to the ListDictionary continue to be reflected in the ICollection.
  • Retrieving the value of this property is an O(1) operation.
Reference:

Last Updated : 01 Feb, 2019
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