In Object-Oriented Programming (OOP), a class is a structure that defines a type of object by describing its properties (attributes) and behaviors (methods). It serves as a template or blueprint for creating objects.

What is a Class?

A class in Python allows you to define:

  • ✅ Attributes — characteristics of the object (e.g., name, age, color)

  • ✅ Methods — actions the object can perform (e.g., speak, eat, sleep)

When a class is defined, no object exists yet. You must instantiate it to create a usable object in memory. Each object (or instance) will have its own values for the attributes and can execute the methods defined in the class.

How to Create a Class in Python

You use the class keyword followed by the name of the class. Inside the class, methods and attributes are defined using indentation.

Here’s a simple example:

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def introduce(self):
        print(f"Hi, my name is {self.name} and I am {self.age} years old.")

Explanation:

  • __init__ is the constructor method, automatically called when a new object is created.

  • self refers to the current instance of the class.

  • introduce() is a method that prints a personal introduction.

Example: Class Cat

Here’s a more complete example using a class to define a cat:

class Cat:
    def __init__(self, name, color, age):
        self.name = name
        self.color = color
        self.age = age
        self.health = "good"       # default attribute
        self.hunger = "satisfied"  # default attribute

    def meow(self):
        print(f"{self.name} is meowing...")

    def eat(self):
        self.hunger = "full"
        print(f"{self.name} is eating.")

    def sleep(self):
        print(f"{self.name} is sleeping.")

    def check_health(self):
        print(f"{self.name}'s health is {self.health}.")

    def check_hunger(self):
        print(f"{self.name} is {self.hunger}.")

In this example, the Cat class has these attributes:

  • name, color, age, health, hunger

And these methods:

  • meow(), eat(), sleep(), check_health(), check_hunger()

Example usage:

my_cat = Cat("Whiskers", "gray", 3)
my_cat.meow()
my_cat.eat()
my_cat.check_hunger()

With this structure, you can create many cat objects, each with unique characteristics and behaviors.

 

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