Mastering Inheritance in C++: Types and Examples Explained

Article by: Manish Methani

Last Updated: October 16, 2021 at 2:04pm IST
9 min 6 sec

Table of Contents:

Introduction

Inheritance is a fundamental concept in C++ that enables a class to inherit properties and behaviors from another class, promoting code reuse and hierarchy within programs.

Syntax of Inheritance

In C++, inheritance syntax involves creating a derived class that inherits attributes and behaviors from a base class. Here's a basic representation:

// Base Class
class Base {
public:
    void display() {
        cout << "This is from the base class." << endl;
    }
};

// Derived Class inheriting from Base
class Derived : public Base {
public:
    void show() {
        cout << "This is from the derived class." << endl;
    }
};

Types of Inheritance

1. Single Inheritance

Single Level Inheritance involves deriving only one class from the base class. It establishes a straightforward parent-child relationship between two classes.

#include <iostream>
using namespace std;

class Base {
public:
    void display() {
        cout <<"This is the Base class" << endl;
    }
};

class Derived : public Base {
public:
    void show() {
        cout << "This is the Derived class" << endl;
    }
};

int main() {
    Derived d;
    d.display(); // Accessing Base class function
    d.show();    // Accessing Derived class function

    return 0;
}

Output:

This is the Base class
This is the Derived class
 

2. Multi-Level Inheritance

Multi-Level Inheritance signifies a chain of inheritance where one derived class becomes the base class for another derived class. It allows for multiple levels of derived classes.

#include <iostream>
using namespace std;

class A {
public:
    void displayA() {
        cout << "This is class A" << endl;
    }
};

class B : public A {
public:
    void displayB() {
        cout << "This is class B" << endl;
    }
};

class C : public B {
public:
    void displayC() {
        cout << "This is class C" << endl;
    }
};

int main() {
    C c;
    c.displayA(); // Accessing Class A method
    c.displayB(); // Accessing Class B method
    c.displayC(); // Accessing Class C method

    return 0;
}

Output:

This is class A
This is class B
This is class C

3. Hierarchical Inheritance

Hierarchical Inheritance occurs when multiple classes are derived from a single base class. It forms a hierarchical structure, branching out from a common base.

#include <iostream>
using namespace std;

class Base {
public:
    void display() {
        cout << "This is the Base class" << endl;
    }
};

class Derived1 : public Base {
public:
    void show1() {
        cout << "This is the first derived class" << endl;
    }
};

class Derived2 : public Base {
public:
    void show2() {
        cout << "This is the second derived class" << endl;
    }
};

int main() {
    Derived1 d1;
    Derived2 d2;
    d1.display(); // Accessing Base class function via first derived class
    d1.show1();   // Accessing first derived class function
    d2.display(); // Accessing Base class function via second derived class
    d2.show2();   // Accessing second derived class function

    return 0;
}

Output:

This is the Base class
This is the first derived class
This is the Base class
This is the second derived class

Multiple Inheritance

Multiple Inheritance occurs when a single class inherits properties and methods from multiple base classes. It provides a way to combine functionalities from different sources.

#include <iostream>
using namespace std;

class A {
public:
    void displayA() {
        cout << "This is class A" << endl;
    }
};

class B {
public:
    void displayB() {
        cout << "This is class B" << endl;
    }
};

class C : public A, public B {
public:
    void displayC() {
        cout << "This is class C" << endl;
    }
};

int main() {
    C c;
    c.displayA(); // Accessing Class A method
    c.displayB(); // Accessing Class B method
    c.displayC(); // Accessing Class C method

    return 0;
} 

Output:

This is class A
This is class B
This is class C

Hybrid Inheritance

Hybrid Inheritance is a combination of multiple inheritance types, encompassing multilevel, multiple, and hierarchical inheritance. It brings together various inheritance forms.

#include <iostream>
using namespace std;

class A {
public:
    void displayA() {
        cout << "This is class A" << endl;
    }
};

class B : public A {
public:
    void displayB() {
        cout << "This is class B" << endl;
    }
};

class C : public A {
public:
    void displayC() {
        cout << "This is class C" << endl;
    }
};

class D : public B, public C {
public:
    void displayD() {
        cout << "This is class D" << endl;
    }
};

int main() {
    D d;
    d.B::displayA(); // Accessing Class A method from class B
    d.C::displayA(); // Accessing Class A method from class C
    d.displayB();    // Accessing Class B method
    d.displayC();    // Accessing Class C method
    d.displayD();    // Accessing Class D method

    return 0;
}

Output:

This is class A
This is class A
This is class B
This is class C
This is class D

Conclusion

Inheritance in C++ allows for the creation of complex class hierarchies, promoting code organization, and reuse. Understanding its types and syntax is crucial for building scalable and maintainable applications.