What is the purpose of an abstract class?

The purpose of an abstract class (often referred to as an ABC) is to provide an appropriate base class from which other classes can inherit . Abstract classes cannot be used to instantiate objects and serves only as an interface. Attempting to instantiate an object of an abstract class causes a compilation error.

The purpose of an abstract class is to provide a blueprint for derived classes and set some rules what the derived classes must implement when they inherit an abstract class . We can use an abstract class as a base class and all derived classes must implement abstract definitions.

By definition, an abstract class in C++ is a class that has at least one pure virtual function (i.e., a function that has no definition). The classes inheriting the abstract class must provide a definition for the pure virtual function; otherwise, the subclass would become an abstract class itself.