C# | Check if a HashSet is a proper superset of the specified collection

Last Updated : 11 Jul, 2025

A HashSet is an unordered collection of the unique elements. It comes under the System.Collections.Generic namespace. It is used in a situation where we want to prevent duplicates from being inserted in the collection. As far as performance is concerned, it is better in comparison to the list. HashSet.IsProperSupersetOf(IEnumerable) Method is used to check if a HashSet is a proper superset of the specified collection or not. Syntax:

mySet1.IsProperSupersetOf(mySet2);

Here, mySet1 and mySet2 are 2 HashSets. Return Value: The function returns true if mySet1 is Proper Superset of mySet2, else returns false. Exception: This method will give ArgumentNullException if the HashSet is empty. Below given are some examples to understand the implementation in a better way: Example 1:

CSHARP

// C# code to Check if a HashSet is a proper
// superset of the specified collection
using System;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a HashSet of integers
        HashSet<int> mySet1 = new HashSet<int>();

        // Inserting elements into HashSet mySet1
        for (int i = 10; i < 20; i++) {
            mySet1.Add(i);
        }

        // Creating a HashSet of integers
        HashSet<int> mySet2 = new HashSet<int>();

        // Inserting elements into HashSet mySet2
        for (int i = 0; i < 25; i++) {
            mySet2.Add(i);
        }

        // Checking if mySet1 is Proper Superset Of mySet2
        // The function returns true if the condition
        // satisfies, else returns false
        Console.WriteLine(mySet1.IsProperSupersetOf(mySet2));
    }
}

Output:

False

Example 2:

CSHARP

// C# code to Check if a HashSet is a proper
// superset of the specified collection
using System;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a HashSet of strings
        HashSet<string> mySet1 = new HashSet<string>();

        // Inserting elements into HashSet mySet1
        mySet1.Add("India");
        mySet1.Add("Japan");
        mySet1.Add("USA");
        mySet1.Add("Spain");
        mySet1.Add("Italy");

        // Creating a HashSet of strings
        HashSet<string> mySet2 = new HashSet<string>();

        // Inserting elements into HashSet mySet2
        mySet2.Add("USA");
        mySet2.Add("Spain");
        mySet2.Add("Italy");

        // Checking if mySet1 is Proper Superset Of mySet2
        // The function returns true if the condition
        // satisfies, else returns false
        Console.WriteLine(mySet1.IsProperSupersetOf(mySet2));
    }
}