FAQ: Interfaces - Build an Interface

This community-built FAQ covers the “Build an Interface” exercise from the lesson “Interfaces”.

Paths and Courses
This exercise can be found in the following Codecademy content:

Learn C#

FAQs on the exercise Build an Interface

There are currently no frequently asked questions associated with this exercise – that’s where you come in! You can contribute to this section by offering your own questions, answers, or clarifications on this exercise. Ask or answer a question by clicking reply (reply) below.

If you’ve had an “aha” moment about the concepts, formatting, syntax, or anything else with this exercise, consider sharing those insights! Teaching others and answering their questions is one of the best ways to learn and stay sharp.

Join the Discussion. Help a fellow learner on their journey.

Ask or answer a question about this exercise by clicking reply (reply) below!
You can also find further discussion and get answers to your questions over in Language Help.

Agree with a comment or answer? Like (like) to up-vote the contribution!

Need broader help or resources? Head to Language Help and Tips and Resources. If you are wanting feedback or inspiration for a project, check out Projects.

Looking for motivation to keep learning? Join our wider discussions in Community

Learn more about how to use this guide.

Found a bug? Report it online, or post in Bug Reporting

Have a question about your account or billing? Reach out to our customer support team!

None of the above? Find out where to ask other questions here!

Could someone please explain how interfaces work with an analogy and what they are used for.
Thank you.


To me, interface is like instructions that tell a class what it should do/have.

When you’re developing a game which that needs classes like warrior, mage, gunslinger, or maybe more.

At some point, you might forget to add a property let’s say “weapon” to some of the classes. Here’s interface comes to the rescue.

It tells you what properties you forgot to add to classes that implement to the interface.

interface IClass
    string Title { get; private set; }
    string Weapon { get; private set; }
    bool WeaponIsOneHanded { get; private set; }

Then we want our classes to promise to the interface and implement its properties.

Class Warrior : IClass
    // constructors
    public Warrior(string title, string weapon, bool weaponIsOneHanded)
        Title = title;
        Weapon = weapon;
        WeaponIsOneHanded = weaponIsOneHanded;

    // properties
    public string Title { get; private set; }
    public string Weapon { get; private set; }
    public bool WeaponIsOneHanded { get; private set; }

If you forget to add some properties such as Weapon then the interface will tell you to implement it, because it doesn’t make sense when warriors have no swords.

Then we call it in the Main method.

class Program
    public static void Main(string[] args)
        Warrior w = new Warrior("Some Name", "Greatsword", false);