Inheritance And Derivation in C++

Inheritance in C++ is a way of creating a new class (derived class) from an existing class (base class). The derived class inherits the properties and methods of the base class, allowing for code reuse and the creation of hierarchical class structures.

In this tutorial, we'll cover the basics of inheritance and derivation in C++.

Include the required headers:

To use the iostream library, include the iostream header.

#include <iostream>

Base Class:

A base class is the class from which the derived class will inherit properties and methods. To create a base class, define it as you would any other class.

Example:

class Vehicle {
public:
    void startEngine() {
        std::cout << "Starting the engine." << std::endl;
    }
};

Derived Class:

A derived class is a class that inherits properties and methods from a base class. To create a derived class, use the : symbol followed by the access specifier and the name of the base class.

Example:

class Car : public Vehicle {
public:
    void honk() {
        std::cout << "Honking the horn." << std::endl;
    }
};

In this example, the Car class inherits from the Vehicle class using the public access specifier. The derived class Car can access the startEngine() method from the base class.

Access Specifiers:

When deriving a class, the access specifier determines how the inherited members will be accessed in the derived class:

public: Inherited members keep their original access specifier in the derived class.
protected: Inherited public and protected members become protected in the derived class.
private: Inherited public and protected members become private in the derived class.

Using Inherited Members:

In the derived class, you can access inherited members as if they were members of the derived class itself.

Example:

#include <iostream>

class Vehicle {
public:
    void startEngine() {
        std::cout << "Starting the engine." << std::endl;
    }
};

class Car : public Vehicle {
public:
    void honk() {
        std::cout << "Honking the horn." << std::endl;
    }

    void drive() {
        startEngine(); // Inherited from Vehicle
        honk();
    }
};

int main() {
    Car myCar;
    myCar.drive();
    return 0;
}

Output:

Starting the engine.
Honking the horn.

In this example, the Car class calls the startEngine() method inherited from the Vehicle class.

Inheritance and derivation are essential concepts in object-oriented programming, as they enable code reuse and the creation of complex class structures. Understanding these concepts will help you write modular and organized code in C++.

How to use inheritance in C++:

Description: Introduces the concept of inheritance, demonstrating how one class can inherit attributes and behaviors from another.

Example Code:

#include <iostream>

// Base class
class Animal {
public:
    void eat() {
        std::cout << "Animal is eating." << std::endl;
    }
};

// Derived class inheriting from Animal
class Dog : public Animal {
public:
    void bark() {
        std::cout << "Dog is barking." << std::endl;
    }
};

int main() {
    Dog myDog;
    myDog.eat();   // Inherited from Animal
    myDog.bark();  // Specific to Dog
    return 0;
}

Abstract classes and pure virtual functions in C++:

Description: Introduces abstract classes and pure virtual functions as a way to achieve abstraction and polymorphism.

Example Code:

#include <iostream>

// Abstract base class
class Shape {
public:
    // Pure virtual function
    virtual void draw() const = 0;
};

// Concrete derived class
class Circle : public Shape {
public:
    // Implementation of pure virtual function
    void draw() const override {
        std::cout << "Drawing a circle." << std::endl;
    }
};

int main() {
    Circle myCircle;
    myCircle.draw();
    return 0;
}