Object-Oriented Programming (OOP) in C++ along with corresponding code examples to illustrate each concept.
A class is a blueprint for creating objects (a particular data structure), and an object is an instance of a class.
#include <iostream>
using namespace std;
class Car {
public:
string brand;
string model;
int year;
void displayInfo() {
cout << "Brand: " << brand << ", Model: " << model << ", Year: " << year << endl;
}
};
int main() {
Car car1;
car1.brand = "Toyota";
car1.model = "Camry";
car1.year = 2021;
car1.displayInfo();
return 0;
}Encapsulation is the bundling of data with the methods that operate on that data. It restricts direct access to some of an object's components.
#include <iostream>
using namespace std;
class Employee {
private:
int salary;
public:
void setSalary(int s) {
salary = s;
}
int getSalary() {
return salary;
}
};
int main() {
Employee emp;
emp.setSalary(50000);
cout << "Employee Salary: " << emp.getSalary() << endl;
return 0;
}Inheritance is a mechanism where a new class is derived from an existing class. The new class inherits attributes and behaviors of the existing class.
#include <iostream>
using namespace std;
class Animal {
public:
void eat() {
cout << "Eating..." << endl;
}
};
class Dog : public Animal {
public:
void bark() {
cout << "Barking..." << endl;
}
};
int main() {
Dog dog1;
dog1.eat();
dog1.bark();
return 0;
}Polymorphism means the ability to take many forms. It allows methods to do different things based on the object it is acting upon.
#include <iostream>
using namespace std;
class Print {
public:
void display(int i) {
cout << "Integer: " << i << endl;
}
void display(double f) {
cout << "Float: " << f << endl;
}
void display(string s) {
cout << "String: " << s << endl;
}
};
int main() {
Print p;
p.display(5);
p.display(5.99);
p.display("Hello");
return 0;
}#include <iostream>
using namespace std;
class Base {
public:
virtual void show() {
cout << "Base class" << endl;
}
};
class Derived : public Base {
public:
void show() override {
cout << "Derived class" << endl;
}
};
int main() {
Base* b;
Derived d;
b = &d;
b->show();
return 0;
}Abstraction means hiding the complex implementation details and showing only the essential features of the object.
#include <iostream>
using namespace std;
class AbstractEmployee {
virtual void askForPromotion() = 0; // Pure virtual function
};
class Employee : public AbstractEmployee {
private:
string name;
int age;
public:
Employee(string empName, int empAge) : name(empName), age(empAge) {}
void askForPromotion() override {
if (age > 30)
cout << name << ", you got promoted!" << endl;
else
cout << name << ", sorry, no promotion for you." << endl;
}
};
int main() {
Employee emp1("John", 35);
Employee emp2("Jane", 25);
emp1.askForPromotion();
emp2.askForPromotion();
return 0;
}Constructors are special member functions of a class that are executed whenever new objects of that class are created. Destructors are used to destroy the objects created by constructors.
#include <iostream>
using namespace std;
class Person {
public:
Person() {
cout << "Constructor called!" << endl;
}
~Person() {
cout << "Destructor called!" << endl;
}
};
int main() {
Person p1;
return 0;
}Operator overloading allows C++ operators to have user-defined meanings on user-defined types (classes).
#include <iostream>
using namespace std;
class Complex {
private:
float real;
float imag;
public:
Complex() : real(0), imag(0) {}
Complex operator + (const Complex& obj) {
Complex temp;
temp.real = real + obj.real;
temp.imag = imag + obj.imag;
return temp;
}
void display() {
cout << "Real: " << real << " Imaginary: " << imag << endl;
}
};
int main() {
Complex c1, c2, result;
c1 = Complex();
c2 = Complex();
result = c1 + c2;
result.display();
return 0;
}Friend functions are those functions that are not a member of a class but have access to its private and protected members.
#include <iostream>
using namespace std;
class Box {
private:
double width;
public:
friend void printWidth(Box b);
void setWidth(double w) {
width = w;
}
};
void printWidth(Box b) {
cout << "Width of box: " << b.width << endl;
}
int main() {
Box b;
b.setWidth(10.0);
printWidth(b);
return 0;
}These examples cover the essential OOP concepts in C++. Each code snippet demonstrates how the concept is applied in practice.