Data Encapsulation and Abstraction

Data Encapsulation and Abstraction
All C++ programs are composed of the following two fundamental elements:
• Program statements code: This is the part of a program that performs actions and they are called methods.
• Program data: The data is the information of the program which affected by the program methods.
Encapsulation is an Object Oriented Programming concept that binds together the data and methods that manipulate the data, and that keeps both safe from outside interference and misuse. Data encapsulation led to the important OOP concept of data hiding.
Data encapsulation is a mechanism of bundling the data, and the methods that use them and data abstraction is a mechanism of exposing only the interfaces and hiding the implementation details from the user.
C++ supports the properties of encapsulation and data hiding through the creation of user-defined types, called classes. We already have studied that a class can contain private and public members. By default, all items defined in a class are private. For example:
class Box
{
private:
double length; // Length of a box
double breadth; // Breadth of a box
double height; // Height of a box
public:
double getVolume(void)
{
return length * breadth * height;
}
};
The variables length, breadth, and height are private. This means that they can be accessed only by other members of the Box class, and not by any other part of your program. This is one way encapsulation is achieved.
Any C++ program where you implement a class with public and private members is an example of data encapsulation and data abstraction. Consider the following example: