1. What is oops

1. OOPS stands for Object oriented programming structure.

2. It helps the developer to think and organize the code in terms of real world objects

3. It also helps to design the code more modular, flexible, reusable and maintainable.

4. OOPs groups related data and functions into classes

2. Explain with a example

In hospital management, "hospital", "doctor", "patient", "treatment", and "medicines" are real world objects. Each object have its own properties and behaviors.

When developing a hospital management application, developer create classes for each real world objects and define the attributes and methods based on its properties and behaviors

3. What is the use of Oops OR why should use oops?

To design modular, flexible, reusable and maintainable code

4. OOPS features

1. Class

Class is a blueprint of real world objects. It has attributes (member variables) and methods (member functions)

2. Object

Object is an instance of a class.

When creating a instance, memory is allocated for the attributes in the object

Each object has seperate memory location to store its own data

3. Inheritance (Code Reusability)

Common code can be written in a base (parent) class and reused in child classes.

4. Polymorphism (Code maintainablity )

You can use the same method name in parent and child classes with different behaviors.

5. Encapsulation ( Security)

1. Hides internal data.

2. Keeps data safe from outside of the class using private and protected access modifiers .

3. Helps to prevent accidental changes.

6. Abstraction

Hides internal logic and shows only relevant details using abstract classes or interfaces.

Summary

Features	Usage	code implementation
Class	To design properties and methods of an object	keyword "class"
Object	To store data	keyword "new"
Inheritance	Share the properties and logic to child class	keyword "extends"
Encapsulation	Hide the data	access modifier "private" , "protected"
Polymorphism	Redefine the function logic	keyword "extends" and redefine the function in child class
Abstraction	Hide internal logic	Abstract class & interface

1. Abstract class vs interface

Both are used for keeping common structure to the child classes

Abstract class has shared properties and shared logics. But interface don't have properties and shared logics

2. Static and non static variables

Static variable is single copy for all objects. but non-static variables are seperate copy for each objects

3. static methods vs non-static methods

in static method, member variables are not accessible. but in non-static method, member variables are accessible