Course Introduction
Data Abstraction
Data abstraction refers to providing only essential information to the outside world and hiding their background details, i.e., to represent the needed information in program without presenting the details.
Data abstraction is a programming (and design) technique that relies on the separation of interface and implementation.
Let's take one real life example of a TV, which you can turn on and off, change the channel, adjust the volume, and add external components such as speakers, VCRs, and DVD players, BUT you do not know its internal details, that is, you do not know how it receives signals over the air or through a cable, how it translates them, and finally displays them on the screen.
Thus, we can say a television clearly separates its internal implementation from its external interface and you can play with its interfaces like the power button, channel changer, and volume control without having any knowledge of its internals.
In C++, classes provides great level of data abstraction. They provide sufficient public methods to the outside world to play with the functionality of the object and to manipulate object data, i.e., state without actually knowing how class has been implemented internally.
For example, your program can make a call to the sort() function without knowing what algorithm the function actually uses to sort the given values. In fact, the underlying implementation of the sorting functionality could change between releases of the library, and as long as the interface stays the same, your function call will still work.
In C++, we use classes to define our own abstract data types (ADT). You can use the cout object of class ostream to stream data to standard output like this −
Source Code:Program to implement the concept of abstraction
/* C++ Program - implement Abstraction */
#include <iostream>
using namespace std;
class Adder {
public:
// constructor
Adder(int i = 0) {
total = i;
}
// interface to outside world
void addNum(int number) {
total += number;
}
// interface to outside world
int getTotal() {
return total;
};
private:
// hidden data from outside world
int total;
};
int main() {
Adder a;
a.addNum(10);
a.addNum(20);
a.addNum(30);
cout << "Total " << a.getTotal() <<endl;
return 0;
}
Output
When the above code is compiled and executed, it produces the following result −
Total 60
Above class adds numbers together, and returns the sum. The public members - addNum and getTotal are the interfaces to the outside world and a user needs to know them to use the class. The private member total is something that the user doesn't need to know about, but is needed for the class to operate properly.
