Encapsulation in C++
C++ Encapsulation :
On this page we will discuss about encapsulation in C++ . With C++ we achieve the functionality to wrap data and functions inside as a single form and keep them safe from outside world and achieve data hiding from and make the code more secure from unauthorised access. This is encapsulation .
Encapsulation in C++ Language
Encapsulation is, however, different. You wrap and bind all related data together in a single form. Sort of like capsuling / binding it together.
Example:
- In a Car the engines, cooling, battery, breaking, clutching system are hosted together in the front of the car. Similarly, the emission systems are clubbed together and are at the end of the car.
- Imagine if the car fails and the engine, battery system, clutching system and brake system etc are scattered all over the car (Rather than being hosted together in the front).The mechanic will face a hard time figuring out what is wrong and will have to open the whole car open and it will take a lot more time for him to figure out what’s wrong.
- Similarly, for a coder to give code more understandable and readable format he groups and encapsulates all the related data together inside a single unit.
Why do people get confused between Encapsulation and Data Abstraction?
With the help of encapsulation in a way we also achieve data abstraction, which is why people think that they are one and the same thing.
- Yes, while doing encapsulation i.e. grouping into single units.
- We simultaneously use access modifiers which directly help in hiding the data and managing its good architecture at the same time.
How Encapsulation is achieved in C++
Encapsulation is a state of binding/wrapping related data or code in one place.
In C++, we achieve this with classes by bundling all data members and member functions within a single class as shown below –
#include <iostream>
using namespace std;
class Rect {
public:
int len;
int breadth;
int calculateArea() {
return len * breadth;
}
};
int main(){
Rect obj;
obj.len = 10;
obj.breadth = 20;
cout << "Area: " << obj.calculateArea();
}
Output
Area: 200
Issues with Above Program & How Data Abstraction Solves it
We are able to directly access the variables length and breadth. Imagine if they were for User class and variables were username and password.
We need to create a protective interface, this is where data abstraction helps us.
We use access specifiers in C++ to achieve Data Abstraction.
Let us have a look at the example below to understand more about it –
- Example 1: Shows how abstraction works using getters and setters
- Example 2: Shows how Data Abstractions works in real life examples
Example 1
#include <iostream>
using namespace std;
class Rect {
// data members are private and can not be accessed directly
// access specifiers
private:
int len;
int breadth;
public:
// setter for length
void setLen(int l){
len = l;
}
// setter for breadth
void setBreadth(int b){
breadth = b;
}
// getter for length
int getLen(){
return len;
}
// getter for breadth
int getBreadth(){
return breadth;
}
int calculateArea() {
return len * breadth;
}
};
int main(){
Rect obj;
// the following will give errors as data members are private now
// obj.len = 10;
// obj.breadth = 20;
// Following will be allowed
// these are called as getters (to get value)
// and setters (to set value)
obj.setLen(10);
obj.setBreadth(20);
cout << "Length:" << obj.getLen() << endl;
cout << "Breadth: " << obj.getBreadth() << endl;
cout << "Area: " << obj.calculateArea();
}
Output
Length:10 Breadth: 20 Area: 200
Example 2
#include <iostream>
using namespace std;
class User {
// data members are private
private:
int userID;
string password;
// member function interface is public
// to allow specific methods to work with data members
public:
void createProfile(int id, string pass){
userID = id;
password = pass;
cout << "User: " << userID << " account created" << endl;
}
// using this we don't give interface to share actual password
// infact the actual password is hidden as private data member
// we just let the user know if he entered the correct password or not
// this is data abstraction
void authenticate(string str){
if(password == str)
cout << "Login Successful";
else
cout << "Incorrect Password";
}
};
int main(){
User user1;
user1.createProfile(1, "pass123456$");
// following will not work as password is private
// user1.password = "1234";
// this will work as function in public
user1.authenticate("pass0000");
return 0;
}
Output
User: 1 account created Incorrect Password
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