Encapsulation

Introduction

Encapsulation is the process of combining data and functions into a single unit called class. Using the method of encapsulation, the programmer cannot directly access the data. Data is only accessible through the functions present inside the class. Data encapsulation led to the important concept of data hiding. Data hiding is the implementation details of a class that are hidden from the user. The concept of restricted access led programmers to write specialized functions or methods for performing the operations on hidden members of the class. Attention must be paid to ensure that the class is designed properly.

Neither too much access nor too much control must be placed on the operations in order to make the class user friendly. Hiding the implementation details and providing restrictive access leads to the concept of abstract data type. Encapsulation leads to the concept of data hiding, but the concept of encapsulation must not be restricted to information hiding. Encapsulation clearly represents the ability to bundle related data and functionality within a single, autonomous entity called a class.

For instance:

class Item { public: int sample(); int example(char *se) int endfunc(); ......... ......... //Other member functions private: int x; float sq; .......... ......... //Other data members };

In the above example, the data members integer x, float sq and other data members and member functions sample (), example (char* se), endfunc () and other member functions are bundled and put inside a single autonomous entity called class Item. This exemplifies the concept of Encapsulation. This special feature is available in object-oriented language C++ but not available in procedural language C. There are advantages of using this encapsulated approach in C++. One advantage is that it reduces human errors. The data and functions bundled inside the class take total control of maintenance and thus human errors are reduced. It is clear from the above example that the encapsulated objects act as a black box for other parts of the program through interaction. Although encapsulated objects provide functionality, the calling objects will not know the implementation details. This enhances the security of the application.

The key strength behind Data Encapsulation in C++ is that the keywords or the access specifier can be placed in the class declaration as public, protected or private. A class placed after the keyword public is accessible to all the users of the class. The elements placed after the keyword private are accessible only to the methods of the class. In between the public and the private access specifier, there exists the protected access specifier. Elements placed after the keyword protected are accessible only to the methods of the class or classes derived from that class.

The concept of encapsulation shows that a non-member function cannot access an object's private or protected data. This adds security, but in some cases the programmer might require an unrelated function to operate on an object of two different classes. The programmer is then able to utilize the concept of friend functions. Encapsulation alone is a powerful feature that leads to information hiding, abstract data type and friend functions.

Features and Advantages of the concept of Encapsulation:

* Makes Maintenance of Application Easier:

Complex and critical applications are difficult to maintain. The cost associated with maintaining the application is higher than that of developing the application properly. To resolve this maintenance difficulty, the object-oriented programming language C++ created the concept of encapsulation which bundles data and related functions together as a unit called class. Thus, making maintenance much easier on the class level.

* Improves the Understandability of the Application

* Enhanced Security:

There are numerous reasons for the enhancement of security using the concept of Encapsulation in C++. The access specifier acts as the key strength behind the concept of security and provides access to members of class as needed by users. This prevents unauthorized access. If an application needs to be extended or customized in later stages of development, the task of adding new functions becomes easier without breaking existing code or applications, thereby giving an additional security to existing application.

In order to benefit from the powerful feature of encapsulation in object-oriented programming language C++, the programmer must use encapsulation properly. To maximize the benefits of encapsulation, the user must minimize the implementation details in external interfaces as needed.