Introduction to Inheritance

📘 Introduction to Inheritance in C++

🔑 Definition:

Inheritance is an Object-Oriented Programming (OOP) concept where one class (child) inherits the properties and behaviors (data members and member functions) of another class (parent).

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🧠 Why Use Inheritance?

• Code reusability: Avoids rewriting the same code again.
• Extensibility: Existing classes can be extended with new features.
• Better structure: Promotes hierarchical class organization.
• Polymorphism support: Enables dynamic method binding (virtual functions).

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🔧 Basic Syntax of Inheritance

class Parent {
   // base class code
};

class Child : access-specifier Parent {
   // derived class code
};

• access-specifier can be public, private, or protected.

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🧪 Example: Simple Inheritance

#include <iostream>
using namespace std;

class Animal {
public:
    void sound() {
        cout << "Animals make sounds" << endl;
    }
};

class Dog : public Animal {
public:
    void bark() {
        cout << "Dog barks" << endl;
    }
};

int main() {
    Dog d;
    d.sound();  // Inherited from Animal
    d.bark();   // Own function
    return 0;
}

✅ Output:

Animals make sounds  
Dog barks

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🧱 Types of Inheritance in C++

Type	Description
Single	One base class → One derived class
Multiple	Multiple base classes → One derived class
Multilevel	Derived class becomes a base for another
Hierarchical	One base class → Multiple derived classes
Hybrid	Combination of two or more types

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🧩 Real-Life Analogy

Imagine a Father class has money and a car. The Son class inherits them.
Now the Son doesn’t need to buy new ones — he can reuse what the Father owns.

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🔐 Access Specifiers in Inheritance

Inherited From	Public Inheritance	Private Inheritance	Protected Inheritance
public	public	private	protected
protected	protected	private	protected
private	Not inherited	Not inherited	Not inherited

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📌 Key Points to Remember

• Base class = parent class
• Derived class = child class
• Inheritance promotes DRY (Don’t Repeat Yourself) principle.
• Constructor of base class runs before derived class constructor.
• Destructor of derived class runs before base class destructor.

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🧾 Summary

• Inheritance allows a class to reuse code from another class.
• It makes programs modular, efficient, and organized.
• Supported in C++ through different types like single, multiple, and multilevel.
• Achieved using : public, : private, or : protected keywords.