ToString() Override

Part of the Object Oriented Programming section of Coddy's C# journey — lesson 38 of 70.

Every class in C# inherits from object, which provides a ToString() method. By default, it returns the fully qualified type name - not very useful when you want to see an object's actual data.

You can override ToString() to return a meaningful string representation of your object:

public class Person
{
    public string Name { get; }
    public int Age { get; }
    
    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }
    
    public override string ToString()
    {
        return $"{Name} ({Age} years old)";
    }
}

Now when you print or concatenate a Person object, you get readable output:

Person p = new Person("Alice", 30);
Console.WriteLine(p);  // Alice (30 years old)

Without the override, this would print something like MyNamespace.Person. The override keyword is required because you're replacing the inherited method from object. This is especially valuable for debugging and logging, where you need quick insight into an object's state.

Challenge

Easy

Let's build a Book class that provides meaningful string representations when printed, making debugging and displaying book information much more intuitive.

You'll organize your code across two files:

Book.cs: Create a Book class in the Library namespace that represents a book with its essential details. Your book should have:
- Three read-only properties: Title (string), Author (string), and Year (int)
- A constructor that accepts title, author, and year in that order
- An overridden ToString() method that returns a formatted string: "{Title}" by {Author} ({Year})
Notice the title should be wrapped in double quotes in the output!
Program.cs: In your main file, create a Book object using input values and print it directly. Thanks to your ToString() override, passing the book object to Console.WriteLine() will automatically display the formatted information instead of the type name.

You will receive three inputs:

Book title (string)
Author name (string)
Publication year (integer)

Print the book object directly using Console.WriteLine().

For example, if the inputs are The Great Gatsby, F. Scott Fitzgerald, and 1925, the output should be:

"The Great Gatsby" by F. Scott Fitzgerald (1925)

The magic here is that you're not calling ToString() explicitly - when you pass an object to Console.WriteLine(), it automatically calls the object's ToString() method. Your override makes this output useful instead of just showing Library.Book!

Cheat sheet

Every class in C# inherits from object, which provides a ToString() method. By default, it returns the fully qualified type name.

Override ToString() to return a meaningful string representation:

public class Person
{
    public string Name { get; }
    public int Age { get; }
    
    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }
    
    public override string ToString()
    {
        return $"{Name} ({Age} years old)";
    }
}

When you print an object, ToString() is called automatically:

Person p = new Person("Alice", 30);
Console.WriteLine(p);  // Alice (30 years old)

The override keyword is required when replacing an inherited method from object.

Try it yourself

using System;
using Library;

class Program
{
    public static void Main(string[] args)
    {
        // Read input
        string title = Console.ReadLine();
        string author = Console.ReadLine();
        int year = Convert.ToInt32(Console.ReadLine());

        // TODO: Create a Book object using the input values

        // TODO: Print the book object directly using Console.WriteLine()
    }
}