HashSet for unique elements in C Sharp (C#) - Mini Project: Build & Apply

HashSet for unique elements

📖 Scenario: You are organizing a guest list for a party. Some guests accidentally appear more than once on the list. You want to make sure each guest is invited only once.

🎯 Goal: Build a program that uses a HashSet to store unique guest names and then display the list of unique guests.

📋 What You'll Learn

Create a HashSet<string> to hold guest names

Add guest names to the HashSet, including duplicates

Use a foreach loop to iterate over the HashSet

Print each unique guest name

💡 Why This Matters

🌍 Real World

Removing duplicates from lists is common when managing contacts, emails, or any collection where uniqueness matters.

💼 Career

Understanding HashSet helps in writing efficient code for data processing, filtering, and ensuring data integrity in software development.

1

Create the initial guest list

Create a List<string> called guestList with these exact names: "Alice", "Bob", "Alice", "Charlie", "Bob".

C Sharp (C#)

// Create the guestList with duplicates
// Your code here

Need a hint?

Use new List<string> { ... } to create the list with the exact names.

2

Create a HashSet for unique guests

Create a HashSet<string> called uniqueGuests and initialize it with the guestList.

C Sharp (C#)

using System.Collections.Generic;

List guestList = new List { "Alice", "Bob", "Alice", "Charlie", "Bob" };

// Create the HashSet uniqueGuests from guestList
// Your code here

Need a hint?

Use the HashSet constructor that takes a collection to remove duplicates.

3

Iterate over the unique guests

Use a foreach loop with the variable guest to iterate over uniqueGuests.

C Sharp (C#)

using System.Collections.Generic;

List guestList = new List { "Alice", "Bob", "Alice", "Charlie", "Bob" };
HashSet uniqueGuests = new HashSet(guestList);

// Use foreach to loop over uniqueGuests
// Your code here

Need a hint?

Write foreach (string guest in uniqueGuests) to loop through the unique names.

4

Print the unique guest names

Inside the foreach loop, write Console.WriteLine(guest); to print each unique guest name.

C Sharp (C#)

using System;
using System.Collections.Generic;

List guestList = new List { "Alice", "Bob", "Alice", "Charlie", "Bob" };
HashSet uniqueGuests = new HashSet(guestList);

foreach (string guest in uniqueGuests)
{
    // Print each guest name
    // Your code here
}

Need a hint?

Use Console.WriteLine(guest); inside the loop to print each name.