What is the difference between a class variable and an instance variable in Python?
Richard W

In Python, class variables and instance variables are both types of variables that are used in object-oriented programming. Here's a detailed explanation of the differences between class variables and instance variables: Class Variables: - Definition: Class variables are variables that are defined within a class but outside any instance methods. They are shared among all instances (objects) of the class. - Scope: Class variables have a class-level scope, meaning they can be accessed by all instances of the class as well as the class itself. - Initialization: Class variables are typically initialized outside any instance methods, often at the beginning of the class definition. - Purpose: Class variables are used to store data that is shared among all instances of the class. They represent attributes or characteristics that are common to all objects of that class. - Access: Class variables can be accessed using the class name followed by the variable name (ClassName.variable) or using any instance of the class (instance.variable). - Example:

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class Car:
    wheels = 4  # Class variable

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

car1 = Car("Toyota")
car2 = Car("Honda")

print(Car.wheels)  # Output: 4
print(car1.wheels)  # Output: 4
print(car2.wheels)  # Output: 4

In this example,wheels is a class variable defined within theCar class. It is shared among all instances of the class (car1 andcar2). The variablebrand is an instance variable specific to each instance. Instance Variables: - Definition: Instance variables are variables that are specific to each instance (object) of a class. They represent unique data or attributes associated with each object. - Scope: Instance variables have an instance-level scope, meaning they can only be accessed by the instance of the class to which they belong. - Initialization: Instance variables are typically initialized within the__init__() method of the class, using theself keyword to refer to the instance itself. - Purpose: Instance variables store data that is unique to each object. They represent specific characteristics or state of individual objects. - Access: Instance variables are accessed using the instance name followed by the variable name (instance.variable). - Example:

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class Car:
    def __init__(self, brand):
   self.brand = brand  # Instance variable

car1 = Car("Toyota")
car2 = Car("Honda")

print(car1.brand)  # Output: Toyota
print(car2.brand)  # Output: Honda

In this example,brand is an instance variable specific to each instance of theCar class. Each object (car1 andcar2) has its own separatebrand variable. Summary: In summary, class variables are shared among all instances of a class and represent common data or attributes. They have a class-level scope and are accessed using the class name or any instance of the class. Instance variables, on the other hand, are specific to each instance of a class and represent unique data or attributes. They have an instance-level scope and are accessed using the instance name. Understanding the differences between class variables and instance variables is essential for designing classes and objects that accurately represent the data and behavior of the problem domain.

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