TeachMate | Interactive Learning Platform

What you'll learn

Model an entity as a class with data and behavior.
Create objects and call their methods.
Name the four pillars of OOP.

Object-Oriented Programming (OOP) organizes code around objects that combine data and behavior.

Problem

A college system stores a student's name, age, and marks and a teacher's name, age, and subject, then acts on them: enroll a student, record marks, teach a class. If the data lives in loose variables and the actions in loose functions, the two drift apart.

Goal: Keep each entity's data and the actions on it together in one named type, instead of loose variables and loose functions.

Student	Teacher
name	name
age	age
marks	subject

A student and a teacher both have data (name, age) and actions (enroll, teach). Keeping the data and the actions together, instead of in loose variables and functions, is what a class does. Once you see that, the syntax below is just how you write it.

Understand

Take something you use every day and list its data and the actions you perform on it. Then decide what a class for it would store and what its methods would do.

Before writing classes, have students trace a small program by hand â€” predict each variable's value line by line. Reading code carefully is the skill OOP builds on.

Four Pillars of OOP

Encapsulation: bundling data and methods, hiding internal details
Inheritance: creating new classes from existing ones
Polymorphism: same interface, different implementations
Abstraction: exposing only essential features

Why OOP?

Models real-world concepts naturally
Promotes code reuse
Makes large programs manageable
Enables polymorphic behavior

Key Concepts

Class: A blueprint (template) for creating objects
Object: An instance of a class
Member variables: Data stored in the object
Member functions: Operations the object can perform

Example: Car Analogy

Class: Car (the blueprint)
Objects: My car, your car, that car (instances)
Attributes: color, speed, fuel (member variables)
Behaviors: accelerate, brake, turn (member functions)

Before OOP

struct Student { string name; int age; };
void printStudent(Student s) { ... }

After OOP

class Student {
    string name;
    int age;
public:
    void print() { ... }
};

OOP is not always the answer. For simple programs, procedural code is fine. Use OOP when you need to model complex relationships and behaviors.

Key takeaway: OOP models real-world entities as objects with data and behavior â€” use it when your program needs to manage complex relationships between entities.

Try it: Pick three real-world objects (a student, a book, a bank account) and list the data and behaviors each would have as a class.

Student

Teacher

name

age

marks

subject

After OOP

class Student {
    string name;
    int age;
public:
    void print() { ... }
};

OOP is not always the answer. For simple programs, procedural code is fine. Use OOP when you need to model complex relationships and behaviors.

Key takeaway: OOP models real-world entities as objects with data and behavior â€” use it when your program needs to manage complex relationships between entities.

Try it: Pick three real-world objects (a student, a book, a bank account) and list the data and behaviors each would have as a class.

Introduction to OOP

Four Pillars of OOP

Why OOP?

Key Concepts

Example: Car Analogy

Before OOP

After OOP

Introduction to OOP

Four Pillars of OOP

Why OOP?

Key Concepts

Example: Car Analogy

Before OOP

After OOP