Abstract Classes and Methods

Abstract Methods

An abstract method is declared using the abstract keyword and does not have a body/ implementation.

There are certain rules we should follow when working with abstract methods. Let’s have a look at these rules.

Rules to be Followed

• In contrast to a non-abstract/normal C# method, an abstract method does not have a body/definition, i.e., it only has a declaration or method signature.

• An abstract method can be declared inside an abstract class or an interface only, more on these later.

• To contain any abstract method in its implementation, a class has to be declared as an abstract class. Non-abstract classes cannot have abstract methods.

• An abstract method cannot be declared with the private or sealed modifier as it has to be implemented in some other class.

• Abstract methods are implicitly virtual so we cannot use the keyword virtual in their declaration.

Just like abstract methods, an abstract property declaration does not provide an implementation of the property accessors, i.e., get and set blocks. It declares that the class supports properties but leaves the accessor implementation to derived classes.

Declaration

Let’s move on to the syntax part. Syntactically, the generalized declaration of an abstract method is as follows: