Question

A member function of a class that is not implemented is called a(n) _________ function.

Short answer

Answer: Pure virtual function

Step-by-step solution

Understanding Classes and Member Functions

In object-oriented programming, a class is a blueprint for creating objects. Objects are instances of a class, and they have attributes and methods (functions) associated with them. Member functions are methods that belong to a class and operate on the attributes (data members) of the class. For example, in a `Person` class, there might be member functions like `get_name()` or `get_age()`.

Identify the Term for an Unimplemented Function

When defining a class, sometimes it is useful to declare a member function without providing its implementation. This means that the function can be part of the class interface, but its implementation is left for derived classes (derived classes are classes that inherit from the base class). A member function that does not have an implementation is called a(n) "pure virtual" function. So, the answer to the exercise is: A member function of a class that is not implemented is called a(n) "pure virtual" function.

Key concepts

Object-Oriented Programming

Object-oriented programming (OOP) is a paradigm that uses "objects" to design software. These objects represent real-world entities and have properties and behaviors. This approach allows us to build programs by modeling real-world entities more intuitively.

Some key principles of OOP include:

• Encapsulation, which involves bundling data and methods that operate on the data within a single unit, or "class."
• Abstraction, which focuses on hiding complex details and showing only the relevant features of an object.
• Inheritance, allowing new classes to inherit properties and behaviors from existing classes, promoting code reuse.
• Polymorphism, where a single function or operator works in different ways depending on the context, promoting flexibility.

OOP is prevalent in languages like C++, Java, and Python, providing frameworks for more organized and maintainable code.

Classes in C++

In C++, a class is a user-defined data type that acts as a blueprint for creating objects. It can contain data members (attributes) and member functions (methods) that operate on the attributes.

When defining a class, you specify:

• Access specifiers (such as `public`, `private`, or `protected`) to control access to class members.
• Constructors and destructors to initialize and clean up objects.
• Member functions to define the behavior of class objects.

An example class for a `Person` might include data members like `name` and `age`, along with member functions such as `getName()` and `setName()`. Classes in C++ provide the foundation for effective object-oriented programming by allowing data bundling and behavior definition in a structured way.

Member Functions

Member functions in C++ are functions that are defined in a class and work with the data attributes of that class. They are integral to performing operations on the data of an object. These functions help define the actions that can be performed on an object, making them crucial for encapsulation in OOP.

There are several types of member functions:

• Accessors (or getters) retrieve the value of an object's attribute without modifying it.
• Mutators (or setters) modify the value of an object's attribute.
• Constructors are special member functions that initialize new objects.
• Destructors clean up resources when an object is no longer in use.

Member functions also determine how objects of a class interact with other classes, providing a robust mechanism to control object behavior.

Inheritance in C++

Inheritance in C++ allows one class (known as the derived class) to inherit the properties and member functions of another class (known as the base class). This mechanism enables code reuse and creates a hierarchical relationship between classes.

Some features of inheritance include:

• Derived classes can add new features in addition to those inherited from the base class.
• It facilitates polymorphism, enabling a unified interface for diverse classes.
• Inheritance supports overriding, where derived classes can provide specific implementations for inherited member functions.

To use inheritance in C++, you use a colon followed by the access specifier and the base class name when defining a derived class. For instance, a `Student` class might inherit from a `Person` class, utilizing common attributes while defining additional features specific to students. Through inheritance, C++ promotes organized code and efficient software development.