🔄 How to define a class variable shared among all instances of a class in Python?

In Python, if you want to define a variable that is shared across all instances of a class, you should define it outside of any method but inside the class — this is called a class variable.

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✅ Correct answer to the question:

> How would you define a class variable that is shared among all instances of a class in Python?

🟢 Option 2: Outside of any method at the class level

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🔍 Let’s review the other options:

🔴 Option 1: Inside the constructor method using self
This creates an instance variable, specific to each object, not shared.

🔴 Option 3: As a local variable inside a method
Local variables are temporary and only exist inside the method scope.

🔴 Option 4: As a global variable outside the class
Global variables are shared across the entire program, not specific to class instances.

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🚗 Simple Example: Class Variable in Action

class Car:
    wheels = 4  # ✅ class variable, shared across all instances

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

car1 = Car("Toyota", "Red")
car2 = Car("BMW", "Blue")

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

Car.wheels = 6  # changing the class variable

print(car1.wheels)  # Output: 6
print(car2.wheels)  # Output: 6

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💡 Key Takeaways:
- self. creates instance variables → unique to each object.
- Class-level variables (outside methods) are shared across all instances.
- Perfect for shared attributes like constants, counters, or shared settings.



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👨‍💻 From: https://t.iss.one/DataScienceQ

1. What is the output of the following code?

x = [1, 2, 3]
y = x
y.append(4)
print(x)

2. Which of the following data types is immutable in Python?
A) List
B) Dictionary
C) Set
D) Tuple

3. Write a Python program to reverse a string without using built-in functions.

4. What will be printed by this code?

def func(a, b=[]):
    b.append(a)
    return b

print(func(1))
print(func(2))

5. Explain the difference between == and is operators in Python.

6. How do you handle exceptions in Python? Provide an example.

7. What is the output of:

print(2 ** 3 ** 2)

8. Which keyword is used to define a function in Python?
A) def
B) function
C) func
D) define

9. Write a program to find the factorial of a number using recursion.

10. What does the *args parameter do in a function?

11. What will be the output of:

list1 = [1, 2, 3]
list2 = list1.copy()
list2[0] = 10
print(list1)

12. Explain the concept of list comprehension with an example.

13. What is the purpose of the __init__ method in a Python class?

14. Write a program to check if a given string is a palindrome.

15. What is the output of:

a = [1, 2, 3]
b = a[:]
b[0] = 10
print(a)

16. Describe how Python manages memory (garbage collection).

17. What will be printed by:

x = "hello"
y = "world"
print(x + y)

18. Write a Python program to generate the first n Fibonacci numbers.

19. What is the difference between range() and xrange() in Python 2?

20. What is the use of the lambda function in Python? Give an example.

#PythonQuiz #CodingTest #ProgrammingExam #MultipleChoice #CodeOutput #PythonBasics #InterviewPrep #CodingChallenge #BeginnerPython #TechAssessment #PythonQuestions #SkillCheck #ProgrammingSkills #CodePractice #PythonLearning #MCQ #ShortAnswer #TechnicalTest #PythonSyntax #Algorithm #DataStructures #PythonProgramming

By: @DataScienceQ 🚀