C# HashSet<T>

C# HashSet class can be used to store, remove or view elements. It does not store duplicate elements. It is suggested to use HashSet class if you have to store only unique elements. It is found in System.Collections.Generic namespace.

Example #1

Let's see an example of generic HashSet<T> class that stores elements using Add() method and iterates elements using for-each loop.

snippet

using System;
using System.Collections.Generic;

public class HashSetExample
{
    public static void Main(string[] args)
    {
        // Create a set of strings
        var names = new HashSet();
        names.Add("Sonoo");
        names.Add("Ankit");
        names.Add("Peter");
        names.Add("Irfan");
        names.Add("Ankit");//will not be added
        
        // Iterate HashSet elements using foreach loop
        foreach (var name in names)
        {
            Console.WriteLine(name);
        }
    }
}

Output

Sonoo Ankit Peter Irfan

Example #2

Let's see another example of generic HashSet<T> class that stores elements using Collection initializer.

snippet

using System;
using System.Collections.Generic;

public class HashSetExample
{
    public static void Main(string[] args)
    {
        // Create a set of strings
        var names = new HashSet(){"Sonoo", "Ankit", "Peter", "Irfan"};
        
        // Iterate HashSet elements using foreach loop
        foreach (var name in names)
        {
            Console.WriteLine(name);
        }
    }
}

Output

Sonoo Ankit Peter Irfan