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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