encapsulation

Back to: C++

Encapsulation is the wrapping up of data and information under a single unit. In Object-Oriented Programming, encapsulation is defined as binding together the data and the functions that manipulate them.

Consider a real-life example of encapsulation. In a company there are different sections: the accounts section, finance section, sales section etc. The finance section handles all the financial transactions and keeps records of all the data related to finance. Similarly, the sales section handles all the sales-related activities and keeps records of all the sales. Now there may arise a situation when for some reason an official from the finance section needs all the data about sales in a particular month. In this case, he is not allowed to directly access the data of the sales section. He will first have to contact an officer in the sales section and then request that they give them the particular data. This is what encapsulation is. Here the data of the sales section and the employees that can manipulate them are wrapped under a single name “sales section”.

Encapsulation also leads to data abstraction or hiding. Using encapsulation also hides the data. In the above example, the data of any of the sections like sales, finance or accounts are hidden from any other section.

In C++ encapsulation can be implemented using class and access modifiers.

Look at the this program:

#include<iostream> 
using namespace std; 
  
class Encapsulation 
{ 
    private: 
        // data hidden from outside world 
        int x; 
          
    public: 
        // function to set value of  
        // variable x 
        void set(int a) 
        { 
            x =a; 
        } 
          
        // function to return value of 
        // variable x 
        int get() 
        { 
            return x; 
        } 
}; 
  
// main function 
int main() 
{ 
    Encapsulation obj; 
      
    obj.set(5); 
      
    cout<<obj.get(); 
    return 0; 
} 
output:

5

In the above program, the variable x is made private. This variable can be accessed and manipulated only using the functions get() and set(), which are present inside the class. Thus we can say that here, the variable x and the functions get() and set() are bound together, which is nothing but encapsulation.

Role of access specifiers in encapsulation

As we have seen in the above example, access specifiers play an important role in implementing encapsulation in C++. The process of implementing encapsulation can be sub-divided into two steps:

1. The data members should be labelled as private using the private access specifiers
2. The member function which manipulates the data members should be labelled as public using the public access specifier