Encapsulation

Need for Encapsulation

 

• Any program of  any programming language contains only two parts.
  i.Data
  ii.Logic
• Out of these two highest priority would be always given to data part.
• Functions /logics would e giving output based on the data.
• There is no proper security for the data part in the structured programming language programs like c - program.
• There was no proper separation between the data and functions of different domains because of which complexity of the programming increases and data insecurity arises
• The concept of proper binding is missing in structured programming languages  

Reason for Data Insecurity in C-Programing language:

• It is the  GLOBAL VARIABLES which leads to the data insecurity in c- programs 
• GLOBAL VARIABLES would be available for both related and unrelated functions also.
• Whenever an unrelated function accesses the data in a wrong way data corruption arises

Sample c -program:

1. #include <stdio.h>
2.  
3. /* global variable declaration */
4. int a = 20;
5.  
6. int main ()
7. {
8.  
9. /* local variable declaration in main function */
10.   int a = 10;
11.   int b = 20;
12.   int c = 0;
13. int mul=0;
14.  
15.  c = sum( a, b);
16.  
17.  printf ("a+b = %d\n",  c);
18.  
19. mul= sum( a, b);
20.  
21. printf ("a*b= %d\n",  mul); 
22. return 0;
23. } 
24.  
25. /* function to add two integers */
26. int sum(int a, int b)
27. {   
28.     return a + b;
29. }
30.  
31. /* function to multiply two integers */
32. int mul(int a, int b)
33. {
34.     return a * b;
35. }

What is Encapsulation?

• The concept of binding the data along with its related and corresponding functions is known as Encapsulation.

 

 

Binding:

• The concept of restricting the availability of the data only to its related areas and related functions it is known as binding.
• Because of binding we can restrict the availability of dta to the unrelated functions
• So that unrelated functions cannot access the data 
• Class is the base for encapsulation

Example program:

1. package com.instanceofjava;
2.  
3. public class Student {
4.  
5. // variables
6.    int rno;
7.     String name;
8.     String clas;
9.     String Address;
10.     int rank;
11.  
12. //setter and getter methods of variables 
13.  
14.  public int getRno() {
15.        return rno;
16.     }
17.  
18. public void setRno(int rno) {
19.        this.rno = rno;
20. }
21.  
22. public String getName() {
23.         return name;
24. }
25.  
26.  public void setName(String name) {
27.         this.name = name;
28. }
29.  
30. public String getClas() {
31.        return clas;
32. }
33.  
34. public void setClas(String clas) {
35.         this.clas = clas;
36. }
37.  
38. public String getAddress() {
39.        return Address;
40. }
41.  
42. public void setAddress(String address) {
43.       Address = address;
44. }
45.  
46. public int getRank() {
47.     return rank;
48.  }
49.  
50. public void setRank(int rank) {
51.         this.rank = rank;
52.  }
53.  
54.     //constructor
55.    Student(int rno,String name,String clas,String Address,int rank){
56.  
57.         this.rno=rno;
58.         this.name=name;
59.         this.clas=clas;
60.  
61.         this.Address=Address;
62.         this.rank=rank;
63.  
64.     }
65.  
66.  public static void main(String args[]){
67.  
68.     Student student= new Student(1, "sai", "class IV", "hyderabad", 1); 
69.  
70.     System.out.println("Name: "+student.getName());
71.     System.out.println("Class: "+student.getClas());
72.     System.out.println("Rno: "+student.getRno());
73.  
74.     System.out.println("Rank: "+student.getRank());
75.     System.out.println("Address: "+student.getAddress());
76.  
77.   }
78. }

 

Output:

1. Name: sai 
2. Class: class IV 
3. Rno: 1 
4. Rank: 1 
5. Address: hyderabad