Class and Object in Python

In Python, Class and Object are the core building blocks of Object Oriented Programming (OOP). They help in organizing code, improving reusability, and modeling real-world entities.

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What is a Class?

A class is a blueprint or template used to create objects. It defines:

• Variables (called attributes)
• Functions (called methods)

A class does not occupy memory until an object is created from it.

Syntax of a Class

class ClassName:
    # attributes
    # methods

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Example of Class in Python

class Student:
    school_name = "ABC Public School"

    def study(self):
        print("Student is studying")

Explanation:

• Student → Class name
• school_name → Class variable
• study() → Method
• self → Refers to current object

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What is an Object?

An object is a real instance of a class. It represents a real-world entity and occupies memory.

Multiple objects can be created from the same class.

Creating an Object

object_name = ClassName()

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Example of Object in Python

s1 = Student()
s2 = Student()

s1.study()
print(s1.school_name)

Output:

Student is studying
ABC Public School

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Using __init__() with Class and Object

The __init__() method is a constructor that initializes object data when an object is created.

class Employee:
    def __init__(self, name, salary):
        self.name = name
        self.salary = salary

    def display(self):
        print(self.name, self.salary)

emp1 = Employee("Chandan", 50000)
emp2 = Employee("Amit", 60000)

emp1.display()
emp2.display()

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Difference Between Class and Object

Class	Object
Blueprint or template	Instance of a class
Does not occupy memory	Occupies memory
Defines attributes and methods	Uses attributes and methods
Declared once	Can create multiple objects

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Real-World Example

Class: Mobile Phone
Objects: iPhone, Samsung, OnePlus

class Mobile:
    def call(self):
        print("Calling...")

iphone = Mobile()
samsung = Mobile()

iphone.call()
samsung.call()

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Class vs Object in Automation Testing

class LoginPage:
    def login(self):
        print("Login successful")

login_test = LoginPage()
login_test.login()

This approach is widely used in:

• Selenium Page Object Model (POM)
• Robot Framework libraries
• Python test automation frameworks

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Common Interview Questions

• What is a class in Python?
• What is an object?
• Difference between class and object?
• What is the role of self?
• What is __init__()?

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Conclusion

Understanding Class and Object is the foundation of Python OOP. Every advanced concept like inheritance, polymorphism, and abstraction depends on these two concepts.

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