What is the difference between Abstract Class and Interface in C#?

An abstract class is a special type of class that acts as a base of other classes and cannot be instantiated. Its developed classes provide the implementation logic of an abstract., The abstract converter is used to make a class abstract, which means some missing implementation needs to be employed in the class derived from it.

It contains both abstract and non -abstract members. An abstract class is necessary to offer basic functionality that can be shared and superseded by multiple classes. It is important to avoid code duplication. The abstract class looks like interfaces but with added purpose.

On the other hand, an interface is not a class that contains only the signature of functionality. It is a pattern with no application. Theoretically speaking, it’s just the characterization methods that contain only the declaration of abstract members such as methods, events, indexers, and properties. It cannot be instantiated directly, and any class can execute its members. Also, a class can implement multiple interfaces; however, a class can only inherit a single class.

Abstract Class and Interface in C# programming language may look similar, but they are two different things. To differentiate between the two, we will be discussing some functions and see where both differ. The first function to consider is multiple inheritances. Since an abstract class is only meant for a class, it does not support the function of multiple inheritances. In contrast, this function of multiple inheritances is supported in the interface. An abstract class might be well-defined with no implementation. However, it can only be implemented through its derived classes. In contrast, an interface is more or less like a pattern, and it is never a class. This means an interface cannot do anything. It is important to note that an abstract class can contain its implementation. On the other hand, an interface doesn't have any code but can come with the signature of any functionality. Unlike an interface, an abstract class has access to modifiers.

There will be times when you will get a bit confused about whether you are going to use Abstract Class or Interface in C#. You will be using an abstract class when you want to create functionality that can be overridden by subclasses. You can also use this when you want to create a subclass that can be properly implemented. A class can only extend one abstract class but it can be effective to be used for different interfaces. Take note that abstract classes can only take non−abstract methods and also definitions. You will also use abstract classes for different purposes. They can be public, private, and also protected. Interfaces, on the other hand, will have a declaration of methods.

There are a lot of people who are a bit unsure of the difference between abstract class and interface. When you say abstract class, you are allowing yourself to create a type of functionality for the different subclasses so that you can properly implement or override. When you use interface, this will provide you with functionality, but unlike abstract class, you will not have the power to implement things. The class can only extend to one abstract class. You can use it for different interfaces easily. Take note that abstract classes may sometimes contain non-abstract methods. It will always depend on what needs to be done.

You will use the abstract class when you are aiming to achieve abstraction in C#. In order to make this possible, there is a need to have one abstract method available. How will you know if there is an abstract method? You need to have a modifier available.

Class interface, on the other hand, will have different properties, events, and so much more. You will know that the interfaces are available after the declaration of the different members. Without this, the interfaces will not be there. Take note that an abstract class will contain a constructor while the class interface will not have a constructor available.