Here’s a brief description of the top 50 Python interview questions that can help prepare for an interview:
1. What are the key features of Python?
Python is an interpreted, dynamically typed, and high-level language. It emphasizes readability, simplicity, and allows integration with other languages. It supports object-oriented, functional, and procedural programming paradigms.
2. What is the difference between Python 2 and Python 3?
Python 2 and Python 3 differ in syntax and behavior. For example, Python 2 uses print as a statement (print “hello”), while Python 3 uses it as a function (print(“hello”)). Python 3 also has better support for Unicode, and division of integers returns a float in Python 3, unlike Python 2.
3. How do you create a list in Python?
A list in Python can be created by enclosing elements in square brackets:
my_list = [1, 2, 3, 4]
4. What is a tuple in Python and how is it different from a list?
A tuple is similar to a list but is immutable (cannot be changed after creation). You create it by using parentheses:
my_tuple = (1, 2, 3, 4)
Note:- Lists are mutable, while tuples are not.
5. What is the purpose of the self keyword in Python?
self refers to the instance of the class in instance methods. It is used to access the instance’s attributes and methods.
6. What are Python decorators and how do they work?
Decorators are functions that modify or enhance the behavior of other functions or methods. They are applied using the @decorator_name syntax. Example:
def decorator_function(func):
def wrapper():
print("Before function call")
func()
print("After function call")
return wrapper
@decorator_function
def say_hello():
print("Hello!")
7. Explain the difference between deepcopy and shallow copy in Python.
Shallow Copy: Creates a new object but references the same elements inside the object (i.e., nested objects are not copied).
Deep Copy: Creates a completely new object and recursively copies all objects found within the original, including nested objects.
8. What is the purpose of the with statement in Python?
The with statement is used to wrap the execution of a block of code, ensuring that resources (like files or network connections) are properly managed (opened and closed).
9. What is a lambda function in Python?
A lambda function is a small anonymous function defined with the lambda keyword. It can take any number of arguments but only has one expression:
add = lambda x, y: x + y
10. What are Python’s built-in data types?
Integer, Float, String, Boolean, List, Tuple, Set, Dictionary, etc.
11. Explain how Python handles memory management.
Python uses automatic memory management, with garbage collection for unused objects and reference counting to track object references.
12. What are Python’s string formatting techniques?
Using the % operator: name = "John"; "Hello %s" % name
Using str.format(): "Hello {}".format(name)
Using f-strings (Python 3.6+): f"Hello {name}"
13. What are the main differences between is and == operators?
== checks for value equality, while is checks for identity (whether two objects are the same in memory).
== (Equality operator): Compares the values of two objects to check if they are equal. It checks if the contents or data of the objects are the same, regardless of whether they are the same object in memory.
a = [1, 2, 3]
b = [1, 2, 3]
print(a == b) # True, because the values are the same
is (Identity operator): Checks if two references point to the same object in memory, i.e., if they are the exact same object. It doesn’t compare the values of the objects but rather their identity (memory address).
Example:
a = [1, 2, 3]
b = [1, 2, 3]
print(a is b) # False, because a and b are different objects in memory
14. What is a set in Python? How is it different from a list?
A set is an unordered collection of unique elements. Unlike lists, sets do not allow duplicate elements and do not maintain order.
15. How can you handle exceptions in Python?
Using try, except, and finally blocks:
try:
# code that may raise an exception
except SomeException as e:
# handle the exception
finally:
# cleanup code
16. What is the difference between append() and extend() in Python lists?
append() adds a single element to the list, while extend() adds multiple elements from an iterable to the list.
17. What are list comprehensions and how do they work?
List comprehensions provide a concise way to create lists. Example
squares = [x**2 for x in range(5)]
18. Explain the use of the global keyword.
The global keyword is used to refer to a global variable inside a function, allowing modification of its value.
19. What is the difference between del and remove() in Python lists?
del removes an element by index, while remove() removes the first occurrence of a specific value.
20. How does Python handle type conversion?
Python provides built-in functions to convert between data types, such as int(), float(), str(), and list().
21. What are Python’s built-in functions for working with iterables?
map(), filter(), zip(), sorted(), enumerate(), all(), any(), etc.
22. What are generators in Python and how do they differ from iterators?
Generators are a type of iterator that generate values lazily (on the fly), using the yield keyword. They don’t store all values in memory, making them memory efficient.
23. Explain the difference between range() and xrange() in Python 2.x.
range() returns a list, while xrange() returns an iterator. In Python 3, range() behaves like xrange().
24. What are Python’s built-in modules for working with dates and times?
datetime, time, calendar, and dateutil
25. What is the use of zip() function in Python?
zip() combines two or more iterables into tuples, pairing corresponding elements.
zip([1, 2, 3], ['a', 'b', 'c']) # [(1, 'a'), (2, 'b'), (3, 'c')]
26. What is the purpose of the assert keyword?
assert is used for debugging. It tests a condition, and if the condition is false, raises an AssertionError.
27. Explain how to implement a Python class and its methods.
A Python class is created using the class keyword, with methods defined using def
class MyClass:
def greet(self):
print("Hello")
28. What is the difference between staticmethod and classmethod?
staticmethod: Does not take self or cls as its first argument.
classmethod: Takes cls as its first argument, which represents the class, not the instance.
29. What is the property decorator and how does it work?
The @property decorator is used to define a method that behaves like an attribute, allowing getter, setter, and deleter functionality for attributes.
30. What are Python’s built-in data structures?
Lists, Tuples, Sets, Dictionaries, and named collections in the collections module (e.g., deque, Counter, defaultdict).
31. Explain the difference between sorted() and sort() in Python.
sorted() returns a new sorted list, while sort() sorts the list in place and modifies the original list.
32. What is the use of defaultdict in Python’s collections module?
A defaultdict is a dictionary that provides a default value for non-existent keys.
33. What is a Counter in Python?
A Counter is a subclass of dict used to count the occurrences of elements in an iterable.
34. What are Python’s built-in modules for working with file input/output?
os, shutil, pathlib, and open().
35. What is the difference between os and shutil modules in Python?
os provides methods for interacting with the operating system, like file manipulation, while shutil provides high-level file operations like copying and moving files.
36. How does Python handle garbage collection?
Python uses reference counting and garbage collection to manage memory, automatically removing unused objects from memory.
37. What is the difference between range and enumerate in Python?
range() generates a sequence of numbers, while enumerate() adds a counter to an iterable and returns pairs of index and value.
38. What are the advantages of using try/except/finally blocks in Python?
They help handle errors gracefully, ensuring that resources are released in finally blocks, even when exceptions occur.
39. Explain Python’s yield keyword and how it works.
yield is used to produce a value from a generator function without returning. The function suspends its state, allowing the function to resume where it left off.
40. What is multithreading in Python? How is it implemented?
Multithreading is a way of executing multiple threads (smaller tasks) in parallel. It is implemented using the threading module.
41. What is the Global Interpreter Lock (GIL) in Python?
The GIL is a mutex that allows only one thread to execute Python bytecode at a time, limiting the concurrency of Python programs on multi-core systems.
42. Explain how Python’s memory management works with reference counting.
Python uses reference counting to track the number of references to an object. When an object’s reference count reaches zero, the object is automatically garbage collected.
43. How do you optimize Python performance for large datasets?
Use generators, avoid unnecessary copies of large data, use numpy for numerical data, and utilize multi-threading or multi-processing for concurrent tasks.
44. What is the difference between async and await in Python?
async defines a function as asynchronous, while await is used to pause the execution of an asynchronous function until the awaited result is ready.
45. Explain the concept of Python’s asyncio module.
The asyncio module provides a framework for writing asynchronous programs using async/await syntax, making it easier to handle concurrent tasks.
46. What is the purpose of init and new methods in Python?
__init__ initializes a new instance of a class, while __new__ creates the instance.47. How do you implement inheritance and polymorphism in Python?
Inheritance is implemented by creating a subclass that inherits from a parent class. Polymorphism allows objects of different classes to be treated as instances of the same class.
48. What are metaclasses in Python? How are they used?
Metaclasses are classes of classes in Python. They define how a class behaves. They can be used to customize class creation by modifying the class during its creation.
49. What are Python’s Context Managers and how do they work?
Python’s context managers are objects that manage resources (like files, network connections, or locks) by automatically handling setup and cleanup. They are typically used with the with statement, which ensures that resources are properly acquired and released, even if an error occurs.
A context manager implements two methods:
__enter__(self): Initializes the resource.
__exit__(self, exc_type, exc_value, traceback): Cleans up the resource, regardless of whether an exception occurred.
Example:
with open('file.txt', 'r') as file:
content = file.read()
# File is automatically closed after the block
The with statement ensures that the file is closed even if an error occurs inside the block.
50. What is Python dictionary?
In Python, a dictionary is a built-in data structure that stores data in key-value pairs.
In Python, a dictionary is a built-in data structure that stores data in key-value pairs. Kindly review complete details here..