C++ Classes

What is a Class?

A class is a user-defined blueprint that bundles data (attributes) and behavior (methods) into one unit. Classes are the foundation of Object-Oriented Programming (OOP).

class ClassName {
  public:          // access specifier
    dataType attribute;
    returnType method() { }
};

Defining and Using a Class

#include <iostream>
using namespace std;

class Car {
  public:
    string brand;
    string model;
    int    year;

    void honk() {
        cout << brand << " goes Beep!" << endl;
    }
};

int main() {
    Car myCar;
    myCar.brand = "Toyota";
    myCar.model = "Corolla";
    myCar.year  = 2022;

    cout << myCar.brand << " " << myCar.model << " (" << myCar.year << ")" << endl;
    myCar.honk();
    return 0;
}

Output:

Toyota Corolla (2022)
Toyota goes Beep!

#include <iostream>
using namespace std;

class Person {
  public:
    string name;
    int    age;
    void introduce() {
        cout << "Hi, I'm " << name << " and I'm " << age << " years old." << endl;
    }
};

int main() {
    Person p1; p1.name = "Alice"; p1.age = 28; p1.introduce();
    Person p2; p2.name = "Bob";   p2.age = 34; p2.introduce();
    return 0;
}

Summary

• A class is a blueprint combining data and behavior.
• Class members are accessed using the dot operator ..
• Always end a class definition with };.