Notes – C++ Object Oriented Programming

Object-Oriented Programming (OOP) is a programming approach that organizes code into objects, combining data and functions that operate on that data.

C++ is a multi-paradigm language, but it strongly supports OOP features.

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Why Use OOP?

• To model real-world entities using code
• Helps write modular, reusable, and maintainable programs
• Makes large-scale software easier to manage

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Four Main Pillars of OOP

Concept	Description
Encapsulation	Bundling data and functions into a single unit (class)
Abstraction	Hiding internal details and showing only necessary info
Inheritance	Reusing code by deriving new classes from existing ones
Polymorphism	Ability of one function to behave differently based on context

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Key OOP Terms in C++

Term	Meaning
Class	Blueprint or template for creating objects
Object	Instance of a class
Method	Function defined inside a class
Data Member	Variable inside a class

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Example: Simple Class and Object

#include <iostream>
using namespace std;

class Car {
public:
    string brand;

    void start() {
        cout << brand << " is starting...\n";
    }
};

int main() {
    Car c1;
    c1.brand = "Toyota";
    c1.start();
    return 0;
}

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Access Specifiers

Specifier	Access Level
public	Accessible from anywhere
private	Accessible only within the class
protected	Accessible in the class and derived classes

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OOP in Action

Feature	Example Use Case
Encapsulation	Hiding data in classes
Inheritance	Creating a Bike class from a Vehicle class
Polymorphism	Overloading functions or overriding methods
Abstraction	Using abstract classes/interfaces