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

Last Updated : 01 Feb, 2019

A HashSet is an unordered collection of the unique elements. It comes under 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<T>.IsSupersetOf(IEnumerable) method is used to check whether a HashSet object is a superset of the specified collection or not.

Syntax:

mySet1.IsSupersetOf(mySet2);

Here, mySet1 and mySet2 are the two HashSets.

Return Value: This method returns True if the HashSet object is a superset of another subset otherwise it retunrs False.

Exception: This method will give ArgumentNullException if the HashSet is null.

Below given are some examples to understand the implementation in a better way:

Example 1:

// C# code to Check if a HashSet is a
// 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 in HashSet
        mySet1.Add("Geeks");
        mySet1.Add("GeeksQuiz");
  
        // Creating a HashSet of strings
        HashSet<string> mySet2 = new HashSet<string>();
  
        // Inserting elements in HashSet
        mySet2.Add("DS");
        mySet2.Add("C++");
        mySet2.Add("Java");
        mySet2.Add("JavaScript");
        mySet2.Add("GeeksQuiz");
        mySet2.Add("Geeks");
  
        // Check if a HashSet is a superset
        // of the specified collection
        // It should return true as HashSet mySet2
        // is superset of HashSet mySet1
        Console.WriteLine(mySet2.IsSupersetOf(mySet1));
    }
}

Output:

True

Example 2:

// C# code to Check if a HashSet is a
// 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 in HashSet
        mySet1.Add(2);
        mySet1.Add(3);
        mySet1.Add(4);
        mySet1.Add(5);
  
        // Creating a HashSet of integers
        HashSet<int> mySet2 = new HashSet<int>();
  
        // Inserting elements in HashSet
        mySet2.Add(3);
        mySet2.Add(4);
        mySet2.Add(5);
        mySet2.Add(6);
  
        // Check if a HashSet is a superset
        // of the specified collection
        // It should return false as HashSet mySet2
        // is not a superset of HashSet mySet1
        Console.WriteLine(mySet2.IsSupersetOf(mySet1));
    }
}

Output:

False

Reference:

https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.hashset-1.issupersetof?view=netframework-4.7.2

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