Base Class And Derived Class In C++ Example

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Jun 28, 2024

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Base Class and Derived Class in C++: A Comprehensive Guide with Examples

In object-oriented programming, a core concept is inheritance, which allows you to create new classes (derived classes) based on existing ones (base classes). This promotes code reusability and modularity. In C++, inheritance is implemented using the colon (:) operator.

Understanding the Concept:

• Base Class: A base class, also known as a parent class or superclass, provides fundamental properties and behaviors.
• Derived Class: A derived class, also known as a child class or subclass, inherits characteristics from the base class and can add its own unique features.

Key Advantages of Inheritance:

• Code Reusability: Derived classes inherit attributes and methods from the base class, reducing the need to write redundant code.
• Code Organization: Inheritance helps structure your code logically by grouping related functionalities into classes.
• Polymorphism: Inheritance enables polymorphism, allowing objects of different classes to be treated as objects of a common type.

Illustrative Example:

Let's consider a scenario involving animals:

#include 
#include 

// Base class: Animal
class Animal {
protected:
    std::string name;
    int age;

public:
    Animal(std::string n, int a) : name(n), age(a) {}

    void displayInfo() {
        std::cout << "Name: " << name << std::endl;
        std::cout << "Age: " << age << std::endl;
    }
};

// Derived class: Dog (inherits from Animal)
class Dog : public Animal {
public:
    Dog(std::string n, int a) : Animal(n, a) {}

    void bark() {
        std::cout << "Woof! Woof!" << std::endl;
    }
};

// Derived class: Cat (inherits from Animal)
class Cat : public Animal {
public:
    Cat(std::string n, int a) : Animal(n, a) {}

    void meow() {
        std::cout << "Meow!" << std::endl;
    }
};

int main() {
    Dog myDog("Buddy", 3);
    Cat myCat("Whiskers", 2);

    myDog.displayInfo();
    myDog.bark();

    std::cout << std::endl;

    myCat.displayInfo();
    myCat.meow();

    return 0;
}

Explanation:

1. Base class Animal: Defines common properties for all animals (name and age).
2. Derived classes Dog and Cat: Inherit from the Animal class.
3. Constructor: Each derived class initializes its base class using the Animal(n, a) constructor.
4. Methods: Both derived classes have specific methods (bark() and meow()) that define their unique behaviors.

Running the code will produce the following output:

Name: Buddy
Age: 3
Woof! Woof!

Name: Whiskers
Age: 2
Meow!

Key Points to Remember:

• Use the public keyword to indicate inheritance.
• Derived classes can add new members (attributes and methods) that are not present in the base class.
• Use the protected access specifier in the base class to make members accessible to derived classes.
• Inheritance promotes code reusability and facilitates code organization.
• Understanding inheritance is crucial for building complex and scalable object-oriented applications.