Python Interview Questions

Python Interview Quiz

Difficulty: All Basic Medium Difficult Topic: All Syntax Functions Operators Exceptions List Comprehension

1. What is the difference between a list and a tuple in Python?
A) Lists are immutable, tuples are mutable.
B) Both are mutable.
C) Both are immutable.
D) Lists are mutable, tuples are immutable.

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2. How do you remove whitespaces from a string in Python?
A) All of the above
B) Use string.replace(' ', '')
C) Use string.strip()
D) Use string.lstrip() and string.rstrip()

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3. What is the output of this code?

d1 = {}
d1['a'] = 1
d1['b'] = 2
d2 = d1
d2['a'] = 10
print(d1)
print(d2)

A) {'a': 10} {'a': 10}
B) {'a': 1, 'b': 2} {'a': 10, 'b': 2}
C) {'a': 1, 'b': 2} {'a': 1, 'b': 2}
D) {'a': 10, 'b': 2} {'a': 10, 'b': 2}

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4. What is a key difference between Python 2 and Python 3 regarding the print statement?
A) There is no difference; print works the same in both.
B) Python 2 doesn't support print statements.
C) In Python 3, print is a function and requires parentheses.
D) Python 2 uses print() while Python 3 uses printf().

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5. What is the output of the following code?

class Foo(object):
    def __init__(self):
        self.x = 5
        self.bubbles = 2
class Buzz(Foo):
    def __init__(self):
        Foo.__init__(self)
        self.bubbles = 'Bubbles'
foo = Foo()
print(foo.x)
print(foo.bubbles)
buzz = Buzz()
print(buzz.x)
print(buzz.bubbles)
foo.x = 22
print(buzz.x)
print(Foo.bubbles)
Foo.bubbles = 'dasf'
print(foo.bubbles)
print(foo.x)

A) 5 2 5 'Bubbles' 22 2 'dasf' 22
B) 5 2 5 'Bubbles' 5 AttributeError
C) 5 2 5 'Bubbles' 22 AttributeError
D) 5 2 5 'Bubbles' 5 2 'dasf' 22

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6. How do you sort a list of dictionaries by 'lastName' in place?
A) my_list.sort(key=d['lastName'])
B) my_list.sort(key=lambda d: d['lastName'])
C) sorted(my_list, key=d['lastName'])
D) sorted(my_list, key=lambda d: d['lastName'])

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7. How do you delete a file in Python?
A) Use shutil.remove('filename')
B) Use file.delete('filename')
C) Use os.remove('filename')
D) Use os.delete('filename')

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8. What is the output of this code? a = {1, 2, 3, 4} b = {2, 3, 4, 5} c = {3, 4, 5, 6} d = {4, 5, 6, 7} v = a.union(b, c) print(v | d)
A) {4, 5, 6, 7}
B) {1, 2, 3, 4}
C) {1, 2, 3, 4, 5, 6}
D) {1, 2, 3, 4, 5, 6, 7}

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9. How does Python's garbage collection work, and what is the `gc` module?
A) Python does not have garbage collection.
B) Python uses mark-and-sweep garbage collection.
C) Python uses reference counting and a cyclic garbage collector.
D) Python uses a stop-the-world garbage collector.

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10. How are arguments passed by value or by reference in Python?
A) By name
B) By value
C) By object reference
D) By reference

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11. What is wrong with the following code?

odd = lambda x: bool(x % 2)
numbers = [n for n in range(10) if odd() if not odd(n)]
for i in range(len(numbers)):
    if odd(numbers[i]):
        del numbers[i]
print(numbers)

A) The code is correct and will run without errors.
B) The list comprehension is correct, but deleting items while iterating causes index errors.
C) The list comprehension is incorrect, and the loop will cause a MemoryError.
D) The lambda function is used incorrectly, and the list comprehension has a syntax error.

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12. How do you create a Unicode string in Python?
A) Use u'text' in Python 3.
B) All strings are Unicode in Python 3.
C) Use b'text' for Unicode strings.
D) Use 'text'.encode('utf-8')

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13. What is the output of the following code and why?

class Foo:
    def __init__(self):
        self.x = 5
        self.bubbles = "Bubbles"
    def buzz(self):
        print(self.bubbles)
f = Foo()
f.buzz()

A) False, because a new list is created.
B) True, because the list is modified in place.
C) True, because the function returns the id of a new list.
D) False, because the ids are different.

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14. What will be the output of `3 / 2` in Python 3?
A) 2
B) 1.5
C) Error
D) 1

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15. What does the `lambda` keyword do in Python?
A) Defines a named function.
B) Creates an anonymous function.
C) Imports a module.
D) Declares a loop.

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16. Which statement best describes the Memento and Observer design patterns?
A) Memento alters an object's behavior when its state changes. Observer encapsulates an algorithm inside a class.
B) Memento captures and restores an object's internal state, whereas Observer notifies multiple classes of changes.
C) Memento defers the exact steps of an algorithm to a subclass. Observer defines a new operation.

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17. What are list and dictionary comprehensions in Python? How do you create them and filter items?
A) Comprehensions are used to create functions.
B) Comprehensions are used to define classes.
C) Comprehensions provide a concise way to create lists or dictionaries with optional filtering.
D) Comprehensions are used for exception handling.

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18. How do you remove values from a Python array?
A) All of the above.
B) Use list.remove(value) to remove by value.
C) Use del list[index] to remove by index.
D) Use list.pop(index) to remove by index.

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19. How do you use Abstract Base Classes (ABCs) in Python, and in what contexts are they suitable?
A) ABCs are used to handle exceptions.
B) ABCs are used for metaprogramming.
C) ABCs are used to create concrete classes.
D) ABCs define a common interface for subclasses to implement specific methods.

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20. What is the output of `[x for x in range(5) if x % 2 == 0]`?
A) [1, 3]
B) [0, 2, 4]
C) [0, 1, 2, 3, 4]
D) [2, 4]

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21. What is the default secondary prompt for continuation lines in Python's interactive mode?
A) >>
B) ..
C) ...
D) >>>

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22. What is the value of z after this code? x = 1 y = 0 z = 0 result = 2 try: z = z + 1 result = x / y z = z + 1 except ZeroDivisionError: z = z + result else: z = z + 1 finally: z = z + 1 z = z + 1 print(z)
A) 3
B) 6
C) 4
D) 5

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23. Which pair best illustrates an abstract-concrete class relationship?
A) Cat - Kitten
B) Colour - Red
C) Truck - Window
D) Planet - Moon

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24. What are the results of 5/2, 5.0/2, and 5*1.0/2 in Python?
A) 2.5, 2.5, 2.5
B) 2, 2.5, 2.5
C) 2, 2, 2.5
D) 2.5, 2, 2.5

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25. How is memory managed in Python?
A) Python uses a mark-and-sweep algorithm.
B) Python uses reference counting and garbage collection.
C) Python uses manual memory management.
D) Python does not manage memory.

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26. Does Python have OOP concepts?
A) No, Python does not support OOP concepts.
B) Python supports OOP but not inheritance.
C) Python only supports procedural programming.
D) Yes, Python supports OOP concepts.

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27. What are Python functions?
A) Functions are reusable blocks of code that perform a specific task.
B) Functions are used for creating classes.
C) Functions are used for exception handling.
D) Functions are used for looping.

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28. What happens when you access x[3] in a list with only 3 elements?
A) It raises an IndexError.
B) It wraps around to the first element.
C) It returns the last element.
D) It returns None.

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29. How do you create a nested comprehension in Python, and how does it compare to traditional for loops?
A) Nested comprehensions are not supported in Python.
B) Nested comprehensions are less concise than for loops.
C) Nested comprehensions use multiple for loops in a single statement and are more concise but can be less readable.
D) Nested comprehensions are used for exception handling.

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30. What is the output of this code?

lst1 = [1, 2, 3]
lst2 = lst1
lst3 = lst2
del lst2[1:2]
print(lst3)

A) [1, 3]
B) [1, 2, 3]
C) []
D) [2, 3]

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31. What happens when you use the += operator on a list with a string in Python?
A) It replaces the list with the string.
B) It raises a TypeError.
C) It appends each character of the string to the list.
D) It concatenates the string to the list as a single element.

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32. Which built-in types in Python are mutable and which are immutable?
A) Mutable: dict, set, tuple; Immutable: list, frozenset, str
B) Mutable: list, dict, set; Immutable: tuple, frozenset, str
C) Mutable: list, tuple, set; Immutable: dict, frozenset, str
D) Mutable: list, dict, tuple; Immutable: set, frozenset, str

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33. In Python's interactive mode, which variable holds the value of the last printed expression?
A) ?
B) -
C) _
D) *

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34. What is a reference to an object in Python?
A) It is a shallow pointer that contains the address of an object.
B) It is the address where the variables and methods of an object are stored.
C) It is the address of a variable only; not the methods of an object.
D) It is the physical address of an object.

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35. What is the output of this code?

list1 = [1, 3, 5, 7, 9]
list2 = [0, 2, 4, 6, 8]
print({x: y for x in list1 for y in list2})

A) {1: 0, 3: 2, 5: 4, 7: 6, 9: 8}
B) {1: 8, 3: 8, 5: 8, 7: 8, 9: 8}
C) {1: [0, 2, 4, 6, 8], 3: [0, 2, 4, 6, 8], ...}
D) {0: 1, 2: 3, 4: 5, 6: 7, 8: 9}

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36. How do you comment multiple lines in Python?
A) Use for comments.
B) Use // for multi-line comments.
C) Use /* */ for multi-line comments.
D) Use triple quotes or # on each line.

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37. How do you install Python on Windows and set the path variable?
A) Download from python.org and check 'Add Python to PATH'.
B) Install via Anaconda.
C) Use pip to install Python.
D) Download from GitHub and manually set the path.

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38. What is the output of this code?

def pair_the_items():
    item_stack = [1, 2, 3, 4]
    idx = 0
    item_pairs = zip(item_stack[idx:-1], item_stack[idx+1:])
    print(type(item_pairs))
    print(f'item pairs: {list(item_pairs)}')
pair_the_items()

A) item pairs: (1, 2, 3, 4)
B) item pairs: [(1, 2), (2, 3), (3, 4)]
C) item pairs: [(1, 2, 3, 4)]
D) item pairs: [(1, 2), (2, 3), (3, 4)]

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39. How can you generate random numbers in Python?
A) Use the numpy module.
B) Use the statistics module.
C) Use the math module.
D) Use the random module.

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40. Given an array of 99 unique numbers from 1 to 100, how do you find the missing number, and what is the run time?
A) Sort the array and find the missing number in O(n log n) time.
B) Use binary search to find the missing number in O(log n) time.
C) Use a hash set to find the missing number in O(n) time.
D) Subtract the sum of the array from 5050 in O(n) time.

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41. How do you copy an object in Python?
A) Use object.copy()
B) Use clone()
C) Use copy.copy() or copy.deepcopy()
D) Use deepcopy() only

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42. How do you remove leading whitespaces from a string in Python?
A) Use string.rstrip()
B) Use string.replace(' ', '')
C) Use string.strip()
D) Use string.lstrip()

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43. What is a generator in Python, and where might you use one?
A) Generators are used for parallel processing.
B) Generators are used for creating lists.
C) Generators yield values one at a time and are memory-efficient.
D) Generators are used for exception handling.

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44. How can you set up a database in Django?
A) Edit settings.py and run 'python manage.py migrate'
B) Edit urls.py and run 'python manage.py makemigrations'
C) Edit admin.py and run 'python manage.py createdb'
D) Edit models.py and run 'python manage.py syncdb'

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45. Which of these is NOT a valid way to handle exceptions in Python?
A) try-finally
B) try-except-else
C) catch-throw
D) try-except

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46. How do you insert an object at a given index in Python?
A) Use list.insert(index, object)
B) Use list.append()
C) Use list[index] = object
D) Use list.add(index, object)

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47. What is the output of this code? d = {'k1': 'alpha'} d.update(key3='gamma') d.update({'k1': 'delta'}) print(d)
A) {'k1': 'alpha'}
B) {'k1': 'delta', 'key3': 'gamma'}
C) {'k1': 'gamma', 'key3': 'delta'}
D) {'k1': 'alpha', 'key3': 'gamma'}

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48. How do you sort a list of dictionaries by multiple keys, such as 'lastName' and then 'firstName'?
A) sorted(my_list, key=lambda d: (d['lastName'], d['firstName']))
B) my_list.sort(key=lambda d: d['lastName'], d['firstName'])
C) sorted(my_list, key=[d['lastName'], d['firstName']])
D) sorted(my_list, key=lambda d: d['lastName'] + d['firstName'])

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49. Which statement is used to force a particular exception to occur in Python?
A) throws
B) throw
C) except
D) raise

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50. What is the value of z after this code? z = 5 x = '456' while z > -1: y = x if y in ('1', '2', '3') or len(y) > 1: break x = x + y if y in ('4', '5', '6'): continue z = z - 1 print(z)
A) 10
B) 5
C) -1
D) 0

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51. What is the output of print(name[-1]) if name = 'Python'?
A) Invalid Syntax
B) End-of-lines
C) n
D) P

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52. Which expression represents 10 to the power of 3 in Python?
A) 10 ** 3
B) 10 ^ 3
C) 10 * 3
D) 10 (3)

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53. What is the purpose of PYTHONPATH, and how do you modify it?
A) PYTHONPATH is used to set the Python interpreter's version.
B) PYTHONPATH is used to set the default encoding.
C) PYTHONPATH is an environment variable for module search paths.
D) PYTHONPATH is used to define virtual environments.

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54. What is the output of this code? from string import * method = 'METHODS' def x(methods): method = str.swapcase(methods) print(('%(method)s' % locals())) methods = str.swapcase(method[:-1]) x(methods)
A) 'methods'
B) 'method'
C) 'METHOD'
D) 'Methods'

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55. How is Python an interpreted language?
A) Python is just-in-time compiled.
B) Python is compiled to machine code.
C) Python is transpiled to another language.
D) Python is interpreted line-by-line.

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56. What is the purpose of *args and **kwargs in Python?
A) *args is for default arguments, **kwargs for variable arguments.
B) *args is for keyword arguments, **kwargs for positional arguments.
C) *args is for positional arguments, **kwargs for keyword arguments.
D) *args is for named arguments, **kwargs for unnamed arguments.

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57. How do you get the current working directory in Python?
A) import os.path; os.path.getcwd()
B) import sys; sys.getcwd()
C) import os; os.getcwd()
D) import pwd; pwd()

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58. What is the difference in variable scope between Python 2 and Python 3 in list comprehensions?
A) List comprehensions are not supported in Python 2.
B) There is no difference in variable scope between Python 2 and Python 3.
C) In Python 2, list comprehensions leak variables; in Python 3, they do not.
D) In Python 2, list comprehensions do not leak variables; in Python 3, they do.

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59. How do you debug a Python program?
A) Use print statements or pdb.
B) Use try-except blocks.
C) Use logging or traceback.
D) Use assert statements.

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60. What is the purpose of the property decorator in Python?
A) The property decorator is used to create class methods.
B) The property decorator is used to define static methods.
C) The property decorator is used to handle exceptions.
D) The property decorator allows methods to be accessed as attributes.

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61. Which utility is used to install or remove Python packages?
A) pep
B) sudo
C) pip
D) yum

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62. What is the output of sorting this array alphabetically by food name and then by number?

foods = ['Apple-1', 'Cucumber-5', 'Apple-33', 'Banana-17', 'Strawberry-15', 'Strawberry-4', 'Apple-4', 'Coconut-7', 'Banana-18', 'Strawberry-23']

A) ['Apple-1', 'Apple-33', 'Apple-4', 'Banana-17', 'Banana-18', 'Coconut-7', 'Cucumber-5', 'Strawberry-15', 'Strawberry-23', 'Strawberry-4']
B) ['Cucumber-5', 'Coconut-7', 'Banana-18', 'Banana-17', 'Apple-33', 'Apple-4', 'Apple-1', 'Strawberry-23', 'Strawberry-15', 'Strawberry-4']
C) ['Strawberry-4', 'Strawberry-15', 'Strawberry-23', 'Coconut-7', 'Cucumber-5', 'Banana-17', 'Banana-18', 'Apple-1', 'Apple-4', 'Apple-33']
D) ['Apple-1', 'Apple-4', 'Apple-33', 'Banana-17', 'Banana-18', 'Coconut-7', 'Cucumber-5', 'Strawberry-4', 'Strawberry-15', 'Strawberry-23']

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63. What is the purpose of Python decorators, and how can they be used?
A) Decorators are used to define classes.
B) Decorators are used to import functions and decorate them.
C) Decorators are used to extend function logic by handle redundant code among multiple functions by wrapping them.
D) Decorators are used to create anonymous functions.

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64. What happens when you multiply a list containing a sublist and modify it?
A) List multiplication creates deep copies of the sublist.
B) Each sublist is independent, so modifying one does not affect others.
C) All sublists are references to the same list, so modifying one affects all.
D) Modifying a sublist will raise an error.

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65. How can we make forms in Python?
A) Use Django or Flask for web forms, Tkinter for GUI forms.
B) Use Flask for GUI forms, Tkinter for web forms.
C) Use PyQt for web forms, Django for GUI forms.
D) Use SQLAlchemy for forms.

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66. What happens when you append to a list while iterating over it in Python?
A) It can lead to infinite loops or errors.
B) It works fine and appends elements correctly.
C) It raises a RuntimeError.
D) It removes elements instead of appending.

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67. How do you count the occurrences of each character in a string and return the result as a dictionary?
A) Use a list to store counts.
B) Use a dictionary with setdefault or defaultdict.
C) Use a tuple to store character frequencies.
D) Use a set to count occurrences.

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