C++ OOPS Concept Tutorial

C++ OOPS Concept Tutorial


C++ OOPS Concept Tutorial
What is C++ OOP
In computer programming, OOP refers to Object-Oriented Programming.
Object-Oriented Programming is a programming methodology that associates data structures with a set of operators which act upon them. 
  • To overcome the limitation of the procedural language the concept was developed.
  • A new way of solving problems with computers.
  • OOP languages provide the programmer, the ability to create class hierarchies.
  • Programmers can create modular and reusable code.
  • Can modify the existing modules.
  • The fundamental idea behind object-oriented languages is to combine into a single unit, both data, and functions. A unit is called an object.
  • Functions inside the objects are called member function provides the way to access data.
  • If you want to read a data item in an object then you call the member function in the object.
  • I will read that data item in the object and return the value. You can’t access the data directly. Data is hidden.
  • Data and its functions are said to be encapsulated into a single entity called an object.
The fundamental features of OOP
  • Encapsulation
  • Data abstraction
  • Inheritance
  • Polymorphism
  • Dynamic Hiding 
  • Message Passing  
  • Extensibility
  • Persistence
  • Delegation
C++ Classes and Objects
C++ Classes/Objects
In computer programming, C++ is an object-oriented programming language. Therefore C++ is totally based on classes and objects, along with its attributes and methods. For example: in real life, there are various types of vehicles like cars, bicycles, trucks, autos, and so on. Therefore vehicles are classes and their types are objects.
Class: 
  • Class is the template (Format).
  • The C++ class mechanism allows users to define their data types. For this reason, Class is called user-defined data-types.
  • Class is created by class keyword.
The class definition has two parts:
  • Class head- compose of keyword class followed by class name.
  • Class body- enclose by pair of curly braces is as follows: {…….}
The Syntax of the class is as follows: 
class class_name
{
private:
// declaration of variables
// declaration of functions
protected:
// declaration of variables
// declaration of functions
public:
// declaration of variables
// declaration of functions
};
Object:  
  • An Object is a Physical existence.
  • An Object is instance of a class.
  • An object is combination of or collection of data and code designed to emulate a physical or abstract entity. 
Objects serve the following purposes:
  • Understanding the real world and a practical base for designers.
  • Decomposition of problems into objects depends on judgment and the nature of the problem.
  • Every object has attributes and behavior called operations.
  • The attributes are the data structures representing the properties of the objects.
The Syntax of object is as follows: 
class_name object_1, object_2, object_3 …… object_n;
Example: Create class and objects then find area of room is as follows
Output
C++ Class Methods
In this tutorial, you can have learned about C++ Class methods that are also called functions.
There is two ways declaration of Methods for our class is as follows:
  1. Defining Member Functions Inside the Class Declaration
  2. Defining Member Functions outside the Class Declaration
  3.  
  1. Defining Member Functions Inside the Class Declaration
  • Member functions defined inside the class declaration are called inline functions
  • Only very short functions, like the one below, should be inline functions
        int getSide()
        { return side; } 
Example
Output
  • Defining Member Functions After the Class Declaration *preferred way
  • Put a function prototype in the class declaration
  • In the function definition, precede the function name with the class name and scope resolution operator (::)
int Square::getSide()
{
return side;
}
Example
Output