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C# | Gets an ICollection containing the keys in the Hashtable
  • Last Updated : 01 Feb, 2019

Hashtable.Keys Property is used to get an ICollection containing the keys in the Hashtable.

Syntax:

public virtual System.Collections.ICollection Keys { get; }

Return Value: This property returns an ICollection containing the keys in the Hashtable.

Note:

  • The order of keys in the ICollection is unspecified.
  • Retrieving the value of this property is an O(1) operation.

Below programs illustrate the use of above-discussed property:



Example 1:




// C# code to get an ICollection containing
// the keys in the Hashtable.
using System;
using System.Collections;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a Hashtable
        Hashtable myTable = new Hashtable();
  
        // Adding elements in Hashtable
        myTable.Add("4", "Even");
        myTable.Add("9", "Odd");
        myTable.Add("5", "Odd and Prime");
        myTable.Add("2", "Even and Prime");
  
        // Get a collection of the keys.
        ICollection c = myTable.Keys;
  
        // Displaying the contents
        foreach(string str in c)
            Console.WriteLine(str + ": " + myTable[str]);
    }
}


Output:

5: Odd and Prime
9: Odd
2: Even and Prime
4: Even

Example 2:




// C# code to get an ICollection containing
// the keys in the Hashtable.
using System;
using System.Collections;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a Hashtable
        Hashtable myTable = new Hashtable();
  
        // Adding elements in Hashtable
        myTable.Add("India", "Country");
        myTable.Add("Chandigarh", "City");
        myTable.Add("Mars", "Planet");
        myTable.Add("China", "Country");
  
        // Get a collection of the keys.
        ICollection c = myTable.Keys;
  
        // Displaying the contents
        foreach(string str in c)
            Console.WriteLine(str + ": " + myTable[str]);
    }
}


Output:

Chandigarh: City
India: Country
China: Country
Mars: Planet

Reference:

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