Constants and readonly fields in C Sharp (C#) - Mini Project: Build & Apply

Constants and readonly fields

📖 Scenario: You are creating a simple program to store information about a car. Some details about the car never change, like the number of wheels, while others can be set once when the car is created and then stay the same, like the car's model year.

🎯 Goal: Build a C# program that uses a const field for the number of wheels and a readonly field for the model year. You will see how to set these values and print them.

📋 What You'll Learn

Create a class called Car.

Add a const int field named NumberOfWheels with the value 4.

Add a readonly int field named ModelYear.

Create a constructor for Car that takes an int parameter to set ModelYear.

Create a method DisplayInfo that prints the number of wheels and model year.

In Main, create a Car object with model year 2023 and call DisplayInfo.

💡 Why This Matters

🌍 Real World

Constants and readonly fields are used in programs to keep important values safe from accidental changes, like fixed settings or initial data.

💼 Career

Understanding constants and readonly fields is important for writing reliable and maintainable code in many software development jobs.

1

Create the Car class with a const field

Create a class called Car and inside it, declare a const int field named NumberOfWheels and set it to 4.

C Sharp (C#)

public class Car
{
    // Your code here
}

Need a hint?

Use public const int NumberOfWheels = 4; inside the Car class.

2

Add a readonly field and constructor

Inside the Car class, add a readonly int field named ModelYear. Then create a constructor for Car that takes an int modelYear parameter and sets the ModelYear field.

C Sharp (C#)

public class Car
{
    public const int NumberOfWheels = 4;

    // Your code here
}

Need a hint?

Use public readonly int ModelYear; and set it inside the constructor.

3

Add a method to display car info

Inside the Car class, add a method called DisplayInfo that prints the number of wheels and the model year using Console.WriteLine. Use the fields NumberOfWheels and ModelYear.

C Sharp (C#)

public class Car
{
    public const int NumberOfWheels = 4;
    public readonly int ModelYear;

    public Car(int modelYear)
    {
        ModelYear = modelYear;
    }

    // Your code here
}

Need a hint?

Use Console.WriteLine with the fields inside DisplayInfo.

4

Create a Car object and show info

In the Main method, create a Car object named myCar with model year 2023. Then call myCar.DisplayInfo() to print the details.

C Sharp (C#)

using System;

public class Car
{
    public const int NumberOfWheels = 4;
    public readonly int ModelYear;

    public Car(int modelYear)
    {
        ModelYear = modelYear;
    }

    public void DisplayInfo()
    {
        Console.WriteLine($"Number of wheels: {NumberOfWheels}");
        Console.WriteLine($"Model year: {ModelYear}");
    }
}

class Program
{
    static void Main()
    {
        // Create a Car object with model year 2023 and call DisplayInfo
        // Your code here
    }
}

Need a hint?

Create the object with new Car(2023) and call DisplayInfo().