What is class also called as?

A class consisting of only virtual methods is called a Pure Abstract Base Class (or Pure ABC) in C++ and is also known as an interface by users of the language. Other languages, notably Java and C#, support a variant of abstract classes called an interface via a keyword in the language.

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What classes include?

a class describes the contents of the objects that belong to it : it describes an aggregate of data fields (called instance variables), and defines the operations (called methods). object: an object is an element (or instance) of a class; objects have the behaviors of their class.

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