Tag: object-oriented programming

new C# class

Hello everybody,

Michael here, and today’s post will cover classes in C#.

What is a C# class? Better yet, what is a programming class in general?

If you’ve learned other programming languages, you’ll certainly have encountered this concept. However, in case you need a refresher, C#, like Java and Python (and possibly many other languages) is what’s known as an object-oriented programming language. Just like with Java and Python, everything comes in classes and objects. All those classes and objects come with their own methods and attributes.

new C# class

Now, how do we construct a C# class? Take a look at this example below:

class Cat
{
    string color = "orange";
    int age = 11;
    string gender = "male";

    static void Main(string[] args)
    {
        Cat orangeCat = new Cat();
        Console.WriteLine(orangeCat.age);

    }
}

11

In this simple Cat class, we have three attributes-color, age, and gender. We also created an object of the Cat class in the Main() (yes C# capitalizes the word Main) method called orangeCat and accessed its age attribute with the following code-orangeCat.age-which returns the value of 11.

  • To access any attribute of a C# object, remember the following syntax: objectname.attributename.

Easy enough right? Now let’s see some new C# class tricks!

new C# class (no default values)

Now, how do we create a C# class with no default values? Let’s take a look:

class NewCat
{
    string color;
    int age;
    string gender;

    public NewCat(string catColor, int catAge, string catGender)
    {
        color = catColor;
        age = catAge;
        gender = catGender;
    }

    static void Main(string[] args)
    {
        NewCat brownCat = new NewCat("brown", 11, "female");
        Console.WriteLine("This is a " + brownCat.color + " cat who is " + brownCat.age + " years old and is a " + brownCat.gender);

    }
}

This is a brown cat who is 11 years old and is a female

In this example, I didn’t declare default values for color, age, and gender. Instead, I used a special method called a constructor to allow any object of the Cat class to be initialized with any possible value for each attribute. The constructor must have the same name as the class (Cat in this case) and can contain as many parameters as you want (3 parameters in my case for color, age, and gender).

Notice how I still declared the color, age, and gender variables before the constructor even though I use these same three variables inside the constructor. Why might that be? The first time I mention color, age and gender, all I did was declare that these variables will be a part of this Cat class. However, when I mentioned them again in the constructor, I actually initialize them to whatever the values of catColor, catAge and catGender are set to in the parameters.

  • Remember that before you initialize a variable with a constructor, you must first declare it!
  • Even though I didn’t give any default values for each variable, I can still access each variable in the same manner I did in the previous example (e.g. objectname.attributename).
  • Yes, since I stored each example as a separate script in the same directory, I used the name NewCat for this class. Keep in mind that if you’re going to create multiple classes in the same directory, you must use different names for each class.

Here are the links to both of today’s scripts in my GitHub:

Thanks for reading,

Michael