C# | Check if a HashSet contains the specified element

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.Contains(T) Method is used to check whether a HashSet object contains the specified element.

Syntax:

mySet.Contains(T item);

Here, mySet is the name of the HashSet and item is the required element to locate in the HashSet object.

Return Type: This method returns true if the HashSet object contains the specified element; otherwise, false.

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

Example 1:

// C# code to check if a HashSet
// contains the specified element
using System;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

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

        // Inserting elements in HashSet
        mySet.Add("DS");
        mySet.Add("C++");
        mySet.Add("Java");
        mySet.Add("JavaScript");

        // Check if a HashSet contains
        // the specified element
        if (mySet.Contains("Java"))
            Console.WriteLine("Required Element is present");
        else
            Console.WriteLine("Required Element is not present");
    }
}

Output:

Required Element is present

Example 2:

// C# code to check if a HashSet
// contains the specified element
using System;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

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

        // Inserting elements in HashSet
        for (int i = 0; i < 5; i++) {
            mySet.Add(i * 2);
        }

        // Check if a HashSet contains
        // the specified element
        if (mySet.Contains(5))
            Console.WriteLine("Required Element is present");
        else
            Console.WriteLine("Required Element is not present");
    }
}

Output:

Required Element is not present

Reference:

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