Question

A class with at least one pure virtual member function is called a(n) ______ function.

Short answer

Question: A class with at least one pure virtual member function is called a(n) _______. Answer: Abstract Base Class (ABC)

Step-by-step solution

Answer Fundamentals

A pure virtual function is a virtual function that does not have a definition within the class and has to be implemented in the derived classes. A class with at least one pure virtual member function is called an Abstract Base Class (ABC).

Fill in the blank

The answer to this exercise is: A class with at least one pure virtual member function is called an Abstract Base Class (ABC) function.

Key concepts

Pure Virtual Function

A pure virtual function is a special type of function that serves as a placeholder for a function that must be implemented in derived classes.

• It is declared in a base class but not defined there.
• A pure virtual function is indicated by using `= 0` syntax, like `virtual void exampleFunction() = 0;`.

This notation tells the compiler that its implementation is expected to be found in any subclass that derives from this base class. This approach helps ensure that all derived classes implement certain functions, making the design more robust and reducing errors. Creating a class with pure virtual functions also implies that we cannot instantiate this base class directly. This means it can only be used to serve as a foundation for other classes.

Virtual Function

Virtual functions are functions in a base class that can be overridden in a derived class. These functions enable polymorphism, allowing the program to decide at runtime which function to call.

• They are declared using the `virtual` keyword in the base class.
• When a virtual function is overridden in a derived class, it provides specific implementation details.

The primary advantage of virtual functions is the ability to achieve dynamic binding, where the most derived version of the function is called, even when referring to a base class pointer or reference. When a base class pointer refers to a derived class object, the overridden function in the derived class is executed. This provides flexibility and is particularly useful when writing programs that need to execute differently depending on the type of derived class object being pointed to.

Derived Classes

Derived classes are created when a class (known as a "base class") is extended to create a new class with additional functionalities. By deriving classes, developers can utilize the existing code (base class) while extending or modifying it through additional methods and properties.

• Derived classes inherit characteristics and behaviors from the base class, allowing them to reuse existing code.
• They can override virtual functions to tailor or make specific implementations.
• Derived classes can also introduce new member functions or data members.

Derivation provides a great way to build a scalable and maintainable code base by promoting reuse and reducing redundancy. Additionally, derived classes can serve as a foundation for further derivation, forming a hierarchy that organizes code in a logical manner. This hierarchy enables well-structured programs that are easier to maintain and extend over time.