C# | Check if a HashSet and a specified collection share common elements

Last Updated : 01 Feb, 2019

A HashSet is an unordered collection of the unique elements. It is found in 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.Overlaps(IEnumerable) Method is used to check whether the current HashSet object and a specified collection share common elements.

Syntax:

mySet1.Overlaps(mySet2);

Where, mySet1 and mySet2 are HashSets.

Return Type: This method returns true if the both HashSets share at least one common element otherwise it returns false.

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

Example 1:

// C# code to Check if a HashSet and a
// specified collection share common elements
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("GeeksforGeeks");
        mySet1.Add("GeeksClasses");
        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");
  
        // Check if a HashSet and a specified
        // collection share common elements
        Console.WriteLine(mySet1.Overlaps(mySet2));
    }
}

Output:

False

Example 2:

// C# code to Check if a HashSet and a
// specified collection share common elements
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(4);
        mySet1.Add(8);
        mySet1.Add(12);
        mySet1.Add(16);
  
        // Creating a HashSet of integers
        HashSet<int> mySet2 = new HashSet<int>();
  
        // Inserting elements in HashSet
        mySet2.Add(4);
        mySet2.Add(8);
        mySet2.Add(15);
        mySet2.Add(20);
  
        // Check if a HashSet and a specified
        // collection share common elements
        Console.WriteLine(mySet1.Overlaps(mySet2));
    }
}

Output:

True

Reference:

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

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