C++ Classes and Objects

C++ Classes and Objects

Classes and objects are the two main aspects of Object-Oriented Programming (OOP).

To understand them, think about a real-world example: a Car.

• A Class is a blueprint. The "Car" class describes what a car should have (color, brand, weight) and what it can do (drive, brake).
• An Object is an actual, physical car built from that blueprint. A red Toyota, a blue Ford, and a black BMW are all objects of the Car class.

When the individual objects are created, they inherit all the variables and functions from the class.

1. Creating a Class

In C++, you create a class using the class keyword, followed by the name of the class. It is standard convention to capitalize the first letter of a class name.

class MyClass {       // The class
  public:             // Access specifier
    int myNum;        // Attribute (int variable)
    string myString;  // Attribute (string variable)
};

• class MyClass: This defines the class named MyClass.
• public:: This is an access specifier. It means that the attributes and methods defined below it can be accessed from outside the class.
• Attributes: The variables myNum and myString are properties of the class.

(Note: Don't forget the semicolon ; at the end of the class definition!)

2. Creating an Object

Once a class is defined, you can create objects from it. To create an object of MyClass, specify the class name, followed by the object name.

To access the class attributes (myNum and myString), use the dot syntax (.) on the object:

#include <iostream>
#include <string>
using namespace std;

class MyClass {
  public:
    int myNum;
    string myString;
};
int main() {
  MyClass myObj;  // Create an object of MyClass
  // Access attributes and set values
  myObj.myNum = 15;
  myObj.myString = "Some text";
  // Print attribute values
  cout << myObj.myNum << "\n";
  cout << myObj.myString << "\n";
  return 0;
}