Passing reference types to methods in C Sharp (C#) - Mini Project: Build & Apply

Passing reference types to methods

📖 Scenario: Imagine you have a simple program that manages a book's details. You want to change the book's title by passing the book object to a method.

🎯 Goal: Learn how to pass a reference type (an object) to a method and modify its properties inside that method.

📋 What You'll Learn

Create a class called Book with a public string property Title

Create an instance of Book with the title "Old Title"

Create a method called ChangeTitle that takes a Book object and changes its Title to "New Title"

Call the ChangeTitle method passing the book instance

Print the book's title after calling the method

💡 Why This Matters

🌍 Real World

In real programs, you often pass objects to methods to update their data, like updating a user's profile or changing settings.

💼 Career

Understanding how reference types work when passed to methods is essential for writing correct and efficient C# code in software development.

1

Create the Book class and a book instance

Create a class called Book with a public string property Title. Then create a variable called myBook and set it to a new Book object with Title set to "Old Title".

C Sharp (C#)

// Define the Book class and create myBook with Title "Old Title"
// Your code here

Need a hint?

Use public string Title { get; set; } inside the class. Create myBook with new Book { Title = "Old Title" }.

2

Create the ChangeTitle method

Create a method called ChangeTitle that takes a Book object parameter named book and sets its Title property to "New Title".

C Sharp (C#)

public class Book
{
    public string Title { get; set; }
}

Book myBook = new Book { Title = "Old Title" };

// Create ChangeTitle method below
// Your code here

Need a hint?

Define void ChangeTitle(Book book) and inside set book.Title = "New Title";.

3

Call the ChangeTitle method with myBook

Call the ChangeTitle method and pass the myBook object as an argument.

C Sharp (C#)

public class Book
{
    public string Title { get; set; }
}

Book myBook = new Book { Title = "Old Title" };

void ChangeTitle(Book book)
{
    book.Title = "New Title";
}

// Call ChangeTitle with myBook
// Your code here

Need a hint?

Simply write ChangeTitle(myBook); to call the method.

4

Print the updated book title

Write a Console.WriteLine statement to print the Title property of myBook.

C Sharp (C#)

public class Book
{
    public string Title { get; set; }
}

Book myBook = new Book { Title = "Old Title" };

void ChangeTitle(Book book)
{
    book.Title = "New Title";
}

ChangeTitle(myBook);

// Print the title of myBook
// Your code here

Need a hint?

Use Console.WriteLine(myBook.Title); to print the updated title.