Understanding Class Variables and Instance Variables in Python

A Beginner’s Guide to Mastering Object-Oriented Programming

Photo by Teng Yuhong on Unsplash

Object-oriented programming (OOP) is a fundamental concept in Python, and understanding class variables and instance variables is crucial for writing efficient and maintainable code. These variables play a vital role in defining the behavior and state of objects, which are the building blocks of OOP.

Class Variables

Class variables are variables that are shared among all instances of a class. They are defined within the class itself, outside of any methods, and are accessible to all instances of the class.

Class variables are typically used to store data that is common to all instances of the class, such as constants or configuration settings. Here’s an example of a class with a class variable:

class Circle:
    pi = 3.14159  # Class variable

    def __init__(self, radius):
        self.radius = radius  # Instance variable

    def area(self):
        return self.pi * self.radius ** 2

In this example, pi is a class variable that stores the value of pi. It is accessible to all instances of the Circle class and can be used in the area method. To access a class variable, you can use the class name or an…