Object-Oriented C++

intermediate

What You'll Learn

Theory

C++ supports object-oriented programming with classes, inheritance, polymorphism, and encapsulation. Its OOP model gives fine-grained control over memory and behavior.

Classes and Objects

A class is a user-defined type that bundles data and functions together:

class Rectangle {
public:
    double width;
    double height;
 
    double getArea() {
        return width * height;
    }
};
 
Rectangle rect;
rect.width = 5.0;
rect.height = 3.0;

Access Specifiers

public — accessible from anywhere
private — accessible only within the class (default for classes)
protected — accessible in the class and derived classes

Encapsulation is achieved by making data private and providing public getter/setter methods.

References vs Pointers

A reference (&) is an alias to an existing variable. Unlike pointers, references cannot be null and cannot be reassigned:

int x = 10;
int& ref = x;  // ref is an alias for x
ref = 20;      // x is now 20

References are commonly used for efficient parameter passing without copying.

Class with Encapsulation

cpp

Why this matters

Object-oriented programming in C++ gives you fine-grained control over memory and behavior while keeping code organized and reusable. Encapsulation, access control, and references are fundamental to writing safe, efficient C++ code.

What's next

In the next lessons, you'll dive deeper into each topic with hands-on examples and exercises.

Exercises

Product Class with Encapsulation

easy

Create a Product class with private fields (name, price, quantity), a constructor, getters, and a method to calculate total value (price * quantity).

Expected Output:

Product: Widget, Price: $19.99, Quantity: 10, Total Value: $199.90