C++ Classes and Objects Tutorial

What is a Class?

A class defines properties and behaviors using members like attributes (variables) and methods (functions).

#include <iostream>
using namespace std;

class Car {
public:
    string brand;
    int year;

    void display() {
        cout << "Brand: " << brand << ", Year: " << year << endl;
    }
};
                

What is an Object?

An object is an instance of a class that holds data and interacts with other objects.

int main() {
    Car car1;               // Create object
    car1.brand = "Toyota";  // Set attributes
    car1.year = 2020;
    car1.display();         // Call method

    return 0;
}
                

Constructor in Classes

Constructors are special methods called when an object is created. They initialize object attributes.

class Car {
public:
    string brand;
    int year;

    Car(string b, int y) {  // Constructor
        brand = b;
        year = y;
    }

    void display() {
        cout << "Brand: " << brand << ", Year: " << year << endl;
    }
};

int main() {
    Car car1("Honda", 2019);
    car1.display();

    return 0;
}
                

Access Specifiers

Access specifiers define the accessibility of class members:

• public: Accessible from outside the class.
• private: Accessible only within the class.
• protected: Accessible within the class and derived classes.

class Person {
private:
    string name;

public:
    void setName(string n) {
        name = n;
    }

    string getName() {
        return name;
    }
};
                

Member Functions

Member functions are functions defined inside or outside the class to operate on its data members.

class Rectangle {
private:
    int width, height;

public:
    void setDimensions(int w, int h) {
        width = w;
        height = h;
    }

    int area() {
        return width * height;
    }
};

int main() {
    Rectangle rect;
    rect.setDimensions(5, 10);
    cout << "Area: " << rect.area() << endl;

    return 0;
}