Classes/Objects

 

What is object oriented programming?

 

This consists of creating objects that contain data and functions. This is different from procedural programming that performs operations on data sequentially. Classes and objects are two main aspects of object oriented programming.

 

Example:

 

Class: Fruits

Objects: Apple, Mango, Cherry

 

Another aspect of this programming is attributes (e.g. Color and size) and methods (e.g. Break and speed) of various objects.

 

Create a Class

 

To create a class we use the keyword class.

 

In the following example the class keyword is used to create a class. Public is the access specifier (In detail later in this module). The variables declared within the class Num and Name_string are attributes. At last use of a semicolon is mandatory.

 

Example:

 

class Name_Class //The class
{
  public //Acess specifier
  int Num; //Attribute
  string Name_string; //Attribute
};

 

Create a object

 

An object is created from a class

 

The syntax includes creating an object of Name_class specify the class name, followed by the object name.

 

We can access the class attributes using (.) on the object

 

Example:

 

#include <iostream>
#include <string>

using namespace std;

class Name_Class //The class
{
  public: //Acess specifier
  int Num; //Attribute
  string Name_string; //Attribute
};

int main() 
{
  Name_Class my_Obj; // Create an object of Name_Class
  // Access attributes and set values
  my_Obj.Num = 16;
  my_Obj.Name_string = "Demo Code";

  // Print values
  cout << my_Obj.Num << "\n"; 
  cout << my_Obj.Name_string; 

  return 0;
}

 

Output:

16
Demo Code