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Inheritance in C++ Explained from Beginner to Advanced

Whether you‘re new to C++ inheritance or looking to expand your knowledge, this comprehensive guide aims to take you from beginner to advanced using clear explanations, visual diagrams, and real-world code examples.

We‘ll cover the fundamentals then quickly ramp up to trickier concepts around multiple inheritance, access specifiers and ambiguity resolution. My goal is to provide both a practical reference and a deeper dive for those interested in C++ minutiae. Expect plenty of sample code, UML diagrams, and best practice calls directly from expert sources.

Here‘s a high-level overview of what we‘ll cover:

Inheritance Basics

  • Core concepts
  • Single inheritance
  • Method overriding
  • Syntax evolution in C++

Multiple Inheritance

  • Real-world examples
  • Design considerations
  • Analysis of issues

Access Specifiers

  • Impact on inheritance
  • Public vs protected vs private
  • Usage best practices

Ambiguity Resolution

  • Virtual inheritance
  • Name hiding and resolution
  • Decision trees

By the end, my aim is ensuring you have the knowledge to employ inheritance appropriately in your own projects.

Let‘s get started!

A Brief History of Inheritance in C++

Inheritance entered the C++ lexicon in 1985 with Release 2.0 which contained a small subset of the functionality we have today. Over successive ANSI and ISO standards, Bjarne Stroustrup and others continued extending support resulting in the rich inheritance-related feature set found in modern C++.

Below is a brief evolution timeline for those interested…

[Insert timeline graphic]

With 30+ years of iterations, C++ now provides very robust inheritance mechanisms…let‘s explore the pillars of this capability.

Inheritance Concepts

At a high-level, inheritance in OOP enables new classes to be defined that inherit attributes and behaviors from existing classes. The existing classes are called base or parent while the new classes are derived, extended or child classes.

For example, we might have a base Car class that defines fundamental attributes any car would have:

Car Class
- numWheels 
- numDoors

We could then define specific types of cars that inherit those common attributes:

ElectricCar Class (derived from Car)
- maxRange 
- batteryType

This derived ElectricCar class automatically gains the numWheels and numDoors attributes without needing to redefine them. This enables reusability helping adhere to the DRY principle of "Don‘t Repeat Yourself".

[Insert DRY principle graphic]

Some key terms:

  • Base Class: The class being inherited from, also parent or superclass
  • Derived Class: The class doing the inheriting, also child or subclass
  • Parent/Child: Inheritance relationship between two classes

With the basics established, let‘s explore types of inheritance…

Types of Inheritance

While single inheritance is the simplest, there are actually several forms of inheritance in C++.

Single Inheritance

As the name suggests, single inheritance is where a class inherits from just one base class. For example:

// Base class
class Machine {
  public:
   bool poweredOn = false;

   powerUp() {
     poweredOn = true; 
   }
};

// Derived class 
class Robot : public Machine {
  public:
   int instructionsRun = 0;

   runProgram() {
     // Run program
   }
};

Here Robot inherits the powerUp() capability from Machine allowing it to leverage existing logic. This models an "is-a" relationship denoting all Robots are kinds of Machines.

Single inheritance reduces complexity helping avoid common issues around ambiguity and unintended consequences. As such, prefer single inheritance until requirements dictate more advanced schemes.

[Insert single inheritance UML diagram]

Next let‘s look at…

Multiple Inheritance

…

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