C++ Classes and Objects

1. Class Declaration and Object Creation

Example of defining a class and creating objects:

#include <iostream>
#include <string>

// Class declaration
class Car {
private:
    std::string brand;
    int year;

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

    // Member function
    void displayInfo() {
        std::cout << "Brand: " << brand << ", Year: " << year << std::endl;
    }
};

int main() {
    // Create objects of class Car
    Car car1("Toyota", 2020);
    Car car2("BMW", 2022);

    // Call member function on objects
    car1.displayInfo();
    car2.displayInfo();

    return 0;
}

2. Access Specifiers: Public and Private

Example demonstrating private and public access specifiers:

#include <iostream>

// Class declaration
class Rectangle {
private:
    double length;
    double width;

public:
    // Constructor
    Rectangle(double l, double w) {
        length = l;
        width = w;
    }

    // Public member function to calculate area
    double calculateArea() {
        return length * width;
    }

    // Public member function to set dimensions
    void setDimensions(double l, double w) {
        length = l;
        width = w;
    }
};

int main() {
    // Create object of class Rectangle
    Rectangle rect(5.0, 3.0);

    // Calculate and display area
    std::cout << "Area of rectangle: " << rect.calculateArea() << std::endl;

    // Update dimensions and calculate area again
    rect.setDimensions(7.0, 4.0);
    std::cout << "Updated area of rectangle: " << rect.calculateArea() << std::endl;

    return 0;
}

3. Constructors and Destructors

Example of constructors and destructor in a class:

#include <iostream>
#include <string>

// Class declaration
class Person {
private:
    std::string name;
    int age;

public:
    // Constructor
    Person(std::string n, int a) : name(n), age(a) {
        std::cout << "Constructor called for " << name << std::endl;
    }

    // Destructor
    ~Person() {
        std::cout << "Destructor called for " << name << std::endl;
    }

    // Member function
    void displayInfo() {
        std::cout << "Name: " << name << ", Age: " << age << std::endl;
    }
};

int main() {
    // Create objects of class Person
    Person person1("Alice", 30);
    Person person2("Bob", 25);

    // Call member function on objects
    person1.displayInfo();
    person2.displayInfo();

    return 0;
}

Conclusion

Classes and objects in C++ provide a powerful mechanism for organizing and structuring code into reusable components. This chapter covered the basics of defining classes, creating objects, using constructors and destructors, and utilizing access specifiers. Understanding classes and objects allows you to implement encapsulation, abstraction, and modular design principles in C++ programming.