Defining a Class in C#

Full lesson:

So far, you've worked with built-in types like int, string, and arrays. But what if you want to model something the language doesn't have a type for — like a Dog, a BankAccount, or a Game?

That's what classes are for. A class lets you define your own type by listing what data it holds and what actions it can perform.

Why classes?

Imagine you're writing a program about dogs. Each dog has a name, an age, and can bark. Without classes, you'd have to track each dog's name in one variable, age in another, and write a separate Bark() method for each. That gets messy fast.

With a class, you bundle all of that into one neat package called Dog:

class Dog {
    // We'll add fields (data) and methods (behavior) here in upcoming lessons.
}

Now whenever your program needs a dog, it asks for one of these Dog objects, and the class makes sure each one has all the right pieces.

The syntax

Defining an empty class in C# looks like this:

class ClassName {
}

Three things to notice:

• The keyword class tells C# you're defining a new type.

• ClassName is the name you choose. By convention, C# class names use PascalCase — capitalized words with no underscores: Dog, BankAccount, HighScore.

• The curly braces { } hold the body of the class. They can be empty for now.

You don't need to do anything inside the class to make it valid — defining it is enough.

Where do classes go?

You can define classes at the top level of your file, right alongside the Solution class that's already there. The order doesn't matter — C# can find Dog whether it's defined above or below the code that uses it.

Properties:

To store data in a class, C# doesn't use public fields with hand-written getters and setters — it uses auto-properties. The { get; set; } shorthand tells C# to generate the backing storage and accessors for you:

class Dog {
    public string Name { get; set; }
    public int Age { get; set; }
}

You'll meet this { get; set; } shorthand in the next lessons and throughout the coding tutorials wherever a class needs to hold data.

Your task

Define an empty class called Dog. The pre-filled code in MainFunction will create an instance of your class and print a confirmation message. If you define the class correctly, the program will compile and print:

Defined the Dog class!