C# | Add element to HashSet

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. Elements can be added to HashSet using HashSet.Add(T) Method.

Syntax:

mySet.Add(T item);

Here mySet is the name of the HashSet.

Parameter:

item: The element to add to the set.

Return Type: This method returns true if the element is added to the HashSet object. If the element is already present then it returns false.

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

Example 1:

// C# code to add element to HashSet 
using System; 
using System.Collections.Generic; 
  
class GFG { 
  
    // Driver code 
    public static void Main() 
    { 
  
        // Creating a HashSet of odd numbers 
        HashSet<int> odd = new HashSet<int>(); 
  
        // Inserting elements in HashSet 
        for (int i = 0; i < 5; i++) { 
            odd.Add(2 * i + 1); 
        } 
  
        // Displaying the elements in the HashSet 
        foreach(int i in odd) 
        { 
            Console.WriteLine(i); 
        } 
    } 
} 

Output:

Example 2:

// C# code to add element to 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 in HashSet 
        mySet.Add("Geeks"); 
        mySet.Add("GeeksforGeeks"); 
        mySet.Add("GeeksClasses"); 
        mySet.Add("GeeksQuiz"); 
  
        // Displaying the elements in the HashSet 
        foreach(string i in mySet) 
        { 
            Console.WriteLine(i); 
        } 
    } 
} 

Output:

Geeks
GeeksforGeeks
GeeksClasses
GeeksQuiz

Reference:

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

C# | Add element to SortedSet

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