Add elements to a HashSet in C#

This post will discuss how to add elements to a HashSet<T> in C#.

1. Using `HashSet<T>.Add()` Method

The HashSet<T> class is a collection that contains all unique elements, in no particular order. The HashSet<T> class provides the standard method Add which adds the specified element to it. It returns true if the element is added to the HashSet<T> and false if the element is already present.

The following example creates a HashSet<T> object and demonstrates the usage of the Add() method.

using System;

using System.Collections.Generic;

public class Example

{

public static void Main()

{

HashSet<int> numbers = new HashSet<int>() { 1, 2, 3, 4 };

numbers.Add(5);

Console.WriteLine(String.Join(", ", numbers)); // 1, 2, 3, 4, 5

}

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2. Using `HashSet<T>.UnionWith()` Method

The HashSet<T>.UnionWith() method modifies the HashSet to contain all elements that are present in itself, the specified collection, or both. It can be used to add multiple values to an existing HashSet<T> object, as shown below:

using System;

using System.Collections.Generic;

public class Example

{

public static void Main()

{

HashSet<int> numbers = new HashSet<int>() { 1, 2, 3, 4 };

List<int> values = new List<int>() { 4, 5 };

numbers.UnionWith(values);

Console.WriteLine(String.Join(", ", numbers)); // 1, 2, 3, 4, 5

}

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That’s all about adding elements to a HashSet<T> in C#.

Add elements to a HashSet in C#

1. Using HashSet<T>.Add() Method

2. Using HashSet<T>.UnionWith() Method

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1. Using `HashSet<T>.Add()` Method

2. Using `HashSet<T>.UnionWith()` Method