C# | Remove the specified element from a HashSet (original) (raw)

Last Updated : 02 Aug, 2022

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.Remove(T) method is used to remove the specified element from a HashSet object.

Syntax:

public bool Remove (T item);

Here, item is the element which is to be removed.

Return Value: The method returns True if the element is successfully found and removed and returns False if item is not found in the HashSet<**T**> object.

Below examples illustrate the use of HashSet.Remove(T) Method:

Example 1:

CSHARP `

// C# code to remove the specified // element from a HashSet 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 even numbers less than
    // equal to 20 in HashSet mySet
    for (int i = 0; i < 10; i++) {
        mySet.Add(i * 2);
    }

    Console.WriteLine("The elements in HashSet are : ");

    // Displaying the elements in HashSet
    foreach(int i in mySet)
    {
        Console.WriteLine(i);
    }

    // Displaying the number of elements in HashSet
    Console.WriteLine("Number of elements are : " + mySet.Count);

    // Removing the element 10 if present
    if (mySet.Contains(10)) {
        mySet.Remove(10);
    }

    Console.WriteLine("The elements in HashSet are : ");

    // Displaying the elements in HashSet
    foreach(int i in mySet)
    {
        Console.WriteLine(i);
    }

    // Displaying the number of elements in HashSet
    Console.WriteLine("Number of elements are : " + mySet.Count);
}

}

`

Output:

The elements in HashSet are : 0 2 4 6 8 10 12 14 16 18 Number of elements are : 10 The elements in HashSet are : 0 2 4 6 8 12 14 16 18 Number of elements are : 9

Example 2:

CSHARP `

// C# code to remove the specified // element from a HashSet 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 into HashSet
    mySet.Add("Data Structures");
    mySet.Add("Algorithms");
    mySet.Add("Java");
    mySet.Add("Puzzles");
    mySet.Add("Coding");

    Console.WriteLine("The elements in HashSet are : ");

    // Displaying the elements in HashSet
    foreach(string i in mySet)
    {
        Console.WriteLine(i);
    }

    // Displaying the number of elements in HashSet
    Console.WriteLine("Number of elements are : " + mySet.Count);

    // Removing the element "JavaScript" if present
    if (mySet.Contains("JavaScript")) {
        mySet.Remove("JavaScript");
    }

    Console.WriteLine("The elements in HashSet are : ");

    // Displaying the elements in HashSet
    foreach(string i in mySet)
    {
        Console.WriteLine(i);
    }

    // Displaying the number of elements in HashSet
    Console.WriteLine("Number of elements are : " + mySet.Count);
}

}

`

Output:

The elements in HashSet are : Data Structures Algorithms Java Puzzles Coding Number of elements are : 5 The elements in HashSet are : Data Structures Algorithms Java Puzzles Coding Number of elements are : 5

Reference: