OOPS basic concept in c++

 OOPS

 

OOP stands for Object-Oriented Programming.

 

Procedural programming is about writing procedures or methods that perform operations on the data, while object-oriented programming is about creating objects that contain both data and methods.

 

Advantages of OOPS

OOP is faster and easier to execute

OOP provides a clear structure for the programs

OOP makes it possible to create full reusable applications with less code and shorter development time

Object-Oriented Programming is a methodology or paradigm to design a program using classes and objects.

It simplifies software development and maintenance by providing some concepts:

 

Object

Class

Inheritance

Polymorphism

Abstraction

Encapsulation

 

 

C++ Classes/Objects

 

Classes in C++................(Collection of objects is called class. It is a logical entity.)

 

Everything in c++ is associated with classes and objects, along with its attributes and methods.

For example: in real life, a car is an object. The car has attributes, such as weight and color, and methods, such as drive and brake.

 

A Class is like an object constructor, or a "blueprint" for creating objects.

 

 

Object-Oriented Programming is a paradigm that provides many concepts, such as inheritance, data binding, polymorphism, etc.

 

Objects in C++..................

 

Object means a real-world entity such as a pen, chair, table, computer, watch, etc.

 

Inheritance in C++...................

 

The capability of a class to derive properties and characteristics from another class is called Inheritance

Inheritance is one of the most important features of Object-Oriented Programming.

 

Sub Class: The class that inherits properties from another class is called Sub class or Derived Class

Super Class: The class whose properties are inherited by a sub-class is called Base Class or Superclass.

 

When one object acquires all the properties and behaviors of a parent object, it is known as inheritance.

It provides code reusability. It is used to achieve runtime polymorphism.

 

It has many Types

 

Single Level Inheritance:

In single inheritance, a class is allowed to inherit from only one class.

i.e. one base class is inherited by one derived class only.

 

Multilevel Inheritance:

In this type of inheritance, a derived class is created from another derived class and that derived classcan be derived from a base class or any other derived class. There can be any number of levels.

 

Multiple Inheritance:

Multiple Inheritance is a feature of C++ where a class can inherit from more than one class.

i.e one subclass is inherited from more than one base class.

 

Hierarchical Inheritance:

In this type of inheritance, more than one subclass is inherited from a single base class.

i.e. more than one derived class is created from a single base class.

 

Hybrid Inheritance:

Hybrid Inheritance is implemented by combining more than one type of inheritance.

For example: Combining Hierarchical inheritance and Multiple Inheritance will create hybrid inheritance in C++

 

 

Encapsulation in C++...............

 

Encapsulation is defined as wrapping up data and information under a single unit.

In Object-Oriented Programming, Encapsulation is defined as binding together the data and the

functions that manipulate them.

Encapsulation in C++.Encapsulation also leads to data abstraction or data hiding. Using encapsulation also hides the data

 

 

Data Abstraction in C++...............

 

Data abstraction is one of the most essential and important features of object-oriented

programming in C++. Abstraction means displaying only essential information and hiding the

details. Data abstraction refers to providing only essential information about the data to the

outside world, hiding the background details or implementation.

 


Constructors/Deconstructor

 

A constructor is a special member function in C++ that is automatically called when an object is created. Its primary purpose is to initialize the object.

 

It has the same name as the class.

Constructors do not have a return type, not even void.

It is called automatically when an object is created.

A constructor with parameters to initialize objects with specific values.

 

Syntax:

 

class MyClass {     // The class

  public:           // Access specifier

    MyClass() {     // Constructor

      cout << "Hello World!";

    }

};

 

It has three types

 

1. Default Constructors

2. Parameterized Constructor

3. Copy Constructor

 

 

Destructor

Destructor is an instance member function that is invoked automatically whenever an object is going to

be destroyed. Meaning, a destructor is the last function that is going to be called before an object is destroyed.

In object-oriented programming, constructors are special methods or functions that initialize an object when it is created.

They are used to set initial values for object attributes or perform setup tasks necessary for the object. In most programming languages, constructors have specific syntax and rules.

 



Here’s a breakdown of constructors and their types:

 

1. Default Constructor

A default constructor is a constructor that takes no arguments or has no parameters. It initializes objects with default values.

 

Characteristics:

 

Automatically provided by the compiler if no other constructor is defined (in some languages like C++).

Can also be explicitly defined by the programmer.

 

 

2. Parameterized Constructor

 

A parameterized constructor takes arguments to initialize the object with specific values.

 

Characteristics:

 

Provides flexibility to set different initial values for each object.

Overcomes the limitation of default constructors.

 

 

3. Copy Constructor

 

A copy constructor creates a new object as a copy of an existing object. It duplicates the values of an existing object into the new one.

 

Characteristics:

 

Usually used for deep copying or custom copying behavior.

Automatically provided by the compiler in languages like C++ unless explicitly defined.

 

 


Polymorphism in C++...............

 

Polymorphism means "many forms", and it occurs when we have many classes that are related to each other by inheritance.

 

Like Inheritance lets us inherit attributes and methods from another class.

Polymorphism uses those methods to perform different tasks. This allows us to perform a single action in different ways.

 

For example, think of a base class called Animal that has a method called animalSound().

Derived classes of Animals could be Pigs, Cats, Dogs, Birds - And they also have their own implementation

of an animal sound (the pig oinks, and the cat meows, etc.):

 

polymorphism is of two types Compile time polymorphism and run time polymorphism

 

 

Compile time polymorphism(Function overloading and operator overloading)------------

 

Function overloading.........

 

When there are multiple functions with the same name but different parameters,

then the functions are said to be overloaded, hence this is known as Function Overloading.

Functions can be overloaded by changing the number of arguments or/and changing the type of arguments.

 

 

operator Overloading.........

 

C++ has the ability to provide the operators with a special meaning for a data type, this ability is known as operator overloading.

For example, we can make use of the addition operator (+) for string class to concatenate two strings.

We know that the task of this operator is to add two operands.

So a single operator ‘+’, when placed between integer operands, adds them and when placed between string operands, concatenates them.

 

used to perform the operations on the user defined datatype  

The advantage of operator overloading is to perform different operations on the same operand

 

 

 

Runtime Polymorphism(Function overriding and virtual functions)

 

Runtime polymorphism (also called dynamic polymorphism) refers to the ability of a program to decide at runtime which method or

function to call.

 

In runtime polymorphism, the compiler resolves the object at run time and then it

decides which function call should be associated with that object.

It is also known as dynamic or late binding polymorphism.

 

( Function Overriding )

 

Function Overriding occurs when a derived class has a definition for one of the member functions of the base class.

That base function is said to be overridden.

 

Virtual Functions......

 

A virtual function is a member function that is declared in the base class using the keyword virtual

and is re-defined (Overridden) in the derived class. It tells the compiler to perform late binding

(Late binding refers to the process of resolving function calls at runtime instead of at compile time.)

where the compiler matches the object with the right called function and executes it during the runtime.

This technique falls under Runtime Polymorphism.

 

This Pointer------------

 

In C++ programming, this is a keyword that refers to the current instance of the class.

There can be 3 main usage of this keyword in C++.

 

It can be used to pass current object as a parameter to another method.

 

It can be used to refer current class instance variable.

 

It can be used to declare indexers.

 

#include<iostream>

using namespace std;

class Test{

private:

   int x;

public:

   void setX (int x)

   {

       this->x = x;

   }

   void print() {

      cout << "x = " << x << endl;

   }

};

 

int main()

{

   Test obj;

   obj.setX(56);

   obj.print();

   return 0;

}

 

 

 

 

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