Lecture: ( by Vikash Das, youtube ) →

https://www.youtube.com/watch?v=ntSYb-tzjBE&list=PLupK5DK91flV45dkPXyGViMLtHadRr6sp&index=3

Notes:

Class vs Object → the core idea of Object Oriented Programming

OOP (Object-Oriented Programming) is a way of writing code by grouping related data and actions together into "objects," modeled on real-world things.

Class = a blueprint / template.

A class describes what a type of something is and can do, but it isn't a real item yet. In the picture, Employee and Phone are classes.

Try imagining the Employee class → When I know a person belongs to this class, I know what a type of this thing is (this person is an employee) and what it can do (can report, travel,…)

Each class has two parts:

• Data attributes (its details / characteristics):
  • Employee → Name, Id, Dep, Salary, Designation
  • Phone → Size, Weight, Camera, FP
• Functions / Methods (the actions it can do):
  • Employee → Report, Presentation, Travel
  • Phone → Call, Photo/Video, Net-Browse
  • A function that lives inside a class is called a method.

Object = one real example made from the class.

When you use the blueprint to create an actual, specific thing, that thing is an object (also called an instance).

• Sam is a real employee → an object of the Employee class.
• XYZ 15 is a real phone → an object of the Phone class.

Each object has its own values for the attributes (Sam's name and salary differ from another employee's), but all objects share the same structure and methods defined by their class.

Easy way to hold it: