Multilevel Inheritance in C++

 

1️⃣ What is Multilevel Inheritance?

Multilevel inheritance is a type of inheritance in C++ where a class is derived from another derived class. It forms a chain of inheritance where a class inherits from another class, which itself inherits from another class.

🔹 Key Features of Multilevel Inheritance

• A derived class acts as a base class for another derived class.
• Forms a hierarchical structure where each level inherits properties from the previous level.
• Helps in code reusability and extending functionalities over multiple levels.

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2️⃣ Syntax of Multilevel Inheritance

class A {
    // Base class
};

class B : public A {
    // Derived from A
};

class C : public B {
    // Derived from B (Multilevel Inheritance)
};

• Here, B inherits from A, and C inherits from B.
• C indirectly inherits from A as well.

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3️⃣ Example: Multilevel Inheritance in C++

#include <iostream>
using namespace std;

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

// Intermediate Derived Class
class Parent : public Grandparent {
public:
    void showParent() {
        cout << "This is the Parent class." << endl;
    }
};

// Final Derived Class
class Child : public Parent {
public:
    void showChild() {
        cout << "This is the Child class." << endl;
    }
};

int main() {
    Child obj;
    
    // Accessing methods from all levels
    obj.showGrandparent();  // Inherited from Grandparent
    obj.showParent();       // Inherited from Parent
    obj.showChild();        // Defined in Child

    return 0;
}

🔹 Output:

This is the Grandparent class.
This is the Parent class.
This is the Child class.

🔹 Explanation:

• Child inherits from Parent, which inherits from Grandparent.
• Child has access to methods from both base classes.

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4️⃣ Real-Life Example: Multilevel Inheritance

Let’s consider a vehicle hierarchy.

#include <iostream>
using namespace std;

// Base Class
class Vehicle {
public:
    void move() {
        cout << "Vehicles can move." << endl;
    }
};

// Derived Class
class Car : public Vehicle {
public:
    void carType() {
        cout << "A car is a type of vehicle." << endl;
    }
};

// Further Derived Class
class SportsCar : public Car {
public:
    void speed() {
        cout << "Sports cars have high speed!" << endl;
    }
};

int main() {
    SportsCar obj;

    obj.move();     // Inherited from Vehicle
    obj.carType();  // Inherited from Car
    obj.speed();    // Defined in SportsCar

    return 0;
}

🔹 Output:

Vehicles can move.
A car is a type of vehicle.
Sports cars have high speed!

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5️⃣ Advantages of Multilevel Inheritance

✅ Code Reusability: Each level reuses code from its parent class.
✅ Organized Hierarchy: Allows modeling real-world relationships.
✅ Improved Maintainability: Changes in the base class reflect in derived classes.

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6️⃣ Disadvantages of Multilevel Inheritance

❌ Increased Complexity: More levels mean harder debugging and maintenance.
❌ Performance Overhead: The compiler needs to trace through multiple levels to access members.
❌ Risk of Ambiguity: If a method with the same name exists in multiple classes, it can lead to ambiguity.

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7️⃣ When to Use Multilevel Inheritance?

✅ When hierarchical relationships exist in the program.
✅ When each derived class extends the functionality of the previous one.
✅ When code reusability across multiple levels is needed.

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8️⃣ Summary of Multilevel Inheritance

Feature	Description
Definition	A derived class inherits from another derived class.
Hierarchy	Forms a chain of inheritance.
Code Reusability	Methods from parent classes are reused in derived classes.
Complexity	Increases with more levels of inheritance.
Real-World Use Cases	Hierarchies like vehicle types, organisms, company structures, etc.

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Would you like me to explain Hierarchical Inheritance or Hybrid Inheritance next? 😊