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Python

Introduction to Python

Python Basics

Cotrol Structures

Data Structures

Date and Time

Functions and Module

File Handling

Python OOP

Advanced Concepts

Python DSA

Searching Algorithms

Sorting Algorithms

Python Classes/Objects

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Python is an object-oriented programming language.
Almost everything in Python is an object.

🔹 Create a Class

Use the class keyword to create a class.

class MyClass:
    x = 10

🔹 Create an Object

Create an object from a class using the class name with parentheses.

obj = MyClass()
print(obj.x)  # Output: 10

🔹 The __init__() Function

The __init__() function is called automatically when the object is created.
It is used to assign values to object properties.

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

p1 = Person("Alice", 25)
print(p1.name)
print(p1.age)

🔹 The self Parameter

The self parameter refers to the current instance.
It is used to access variables and methods within the class.

class Car:
    def __init__(self, model):
        self.model = model

    def show(self):
        print("Car model is:", self.model)

c1 = Car("Tesla")
c1.show()

🔹 Modify Object Properties

You can modify property values after object creation.

p1.age = 30
print(p1.age)

🔹 Add Object Methods

Objects can also have methods (functions inside a class).

class Student:
    def __init__(self, name):
        self.name = name

    def greet(self):
        print("Hello", self.name)

s = Student("John")
s.greet()

🔹 Delete Object Properties

Use del to delete properties or entire objects.

del p1.age  # Delete property
del p1      # Delete object

Practice Questions

Q1. Write a Python program to create a class named Laptop with properties brand and price.

Q2. Write a Python program to use the __init__() method to initialize the properties of the Laptop class.

Q3. Write a Python program to create two objects of the Laptop class and print their details.

Q4. Write a Python program to add a method discount() that reduces the price by a given amount or percentage.

Q5. Write a Python program to modify the value of the price property after the object is created.

Q6. Write a Python program to add a method that returns a full description of the laptop (e.g., brand and price).

Q7. Write a Python program to create a class Teacher with attributes name and subject.

Q8. Write a Python program to use self to access and print the teacher’s information inside a method.

Q9. Write a Python program to delete the subject property of a Teacher object using the del keyword.

Q10. Write a Python program to delete the entire object of the Teacher class using the del keyword.

Python Classes/Objects Quiz

Q1: What is a class in Python?

A. A type of variable
B. A blueprint for objects
C. A list of functions
D. A string container

Q2: What is an object?

A. A loop
B. A class itself
C. An instance of a class
D. A built-in module

Q3: What is the purpose of the __init__() function?

A. To print data
B. To create new classes
C. To initialize object properties
D. To delete objects

Q4: What does the self keyword refer to?

A. The whole script
B. The class name
C. The current object
D. None of the above

Q5: Which keyword is used to define a class?

A. struct
B. class
C. define
D. object

Q6: What is required when creating an object?

A. File name
B. Function name
C. Class name with parentheses
D. Variable name

Q7: Can a class have multiple objects?

A. Yes
B. No
C. Only if it’s a string
D. Only one per script

Q8: What can objects contain?

A. Methods only
B. Properties only
C. Both methods and properties
D. Only numbers

Q9: How can you remove a property from an object?

A. remove()
B. del
C. erase
D. discard

Q10: What happens if you try to print a deleted object?

A. It prints “None”
B. It throws an error
C. It runs normally
D. It reloads the object
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