Interface #

An interface is a blueprint for a class which means that it only must contains abstract methods.

Whereas a class can inherit from only one class, it can implement multiple interfaces.

• Like abstract classes, interfaces cannot be instantiated.
• Unlike abstract classes, interfaces do not contain fields.
• Interface can contain properties and methods.
  • Properties and fields are not the same thing!

interface Animal {
    void Speak();
}

class Dog : Animal {
    public void Speak() {
        Console.WriteLine("Woof!");
    }
}

class Cat : Animal {
    public void Speak() {
        Console.WriteLine("Meow!");
    }
}

class Program{
    public static void Main(string[] args){
        var dog = new Dog();
        dog.Speak(); // Woof!

        var cat = new Cat();
        cat.Speak(); // Meow!
    }
}