Top 10 Python interview questions with answers:
1. What are Python's key data types?
Solution:
Numeric types: int, float, complex
Text type: str
Sequence types: list, tuple
Mapping type: dict
Set types: set, frozenset
Boolean type: bool
2. What is a list comprehension in Python?
Solution:
A concise way to create lists using a single line of code.
Example:
squares = [x**2 for x in range(10)] # [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
3. What is the difference between == and is in Python?
Solution:
== checks for value equality.
is checks for object identity (whether two references point to the same object).
a = [1, 2, 3]
b = [1, 2, 3]
print(a == b) # True, values are equal
print(a is b) # False, different objects
4. How do you handle exceptions in Python?
Solution:
Using try, except, else, and finally blocks.
Example:
try:
result = 10 / 0
except ZeroDivisionError:
print("Cannot divide by zero!")
else:
print("No error occurred.")
finally:
print("This block runs regardless of an error.")
5. What are Python decorators and why are they used?
Solution:
Decorators are functions that modify the behavior of other functions or methods. They are used for adding functionality without changing the original function's code. Example:
def my_decorator(func):
def wrapper():
print("Something is happening before the function is called.")
func()
print("Something is happening after the function is called.")
return wrapper
@my_decorator
def say_hello():
print("Hello!")
say_hello()
6. What is a Python generator?
Solution:
A generator is a function that uses yield to return an iterator, which generates values on the fly without storing them in memory. Example:
def my_generator():
yield 1
yield 2
yield 3
gen = my_generator()
for value in gen:
print(value)
7. How do you create a dictionary in Python?
Solution:
my_dict = {'name': 'John', 'age': 30, 'city': 'New York'}
8. What is the difference between append() and extend() in Python?
Solution:
append(): Adds a single element to the end of a list.
extend(): Adds all elements from an iterable to the end of a list.
my_list = [1, 2, 3]
my_list.append([4, 5]) # [1, 2, 3, [4, 5]]
my_list.extend([6, 7]) # [1, 2, 3, [4, 5], 6, 7]
9. What is a lambda function in Python?
Solution:
A lambda function is an anonymous function defined using the lambda keyword. It's often used for short, simple operations. Example:
square = lambda x: x**2
print(square(5)) # 25
10. What is the Global Interpreter Lock (GIL)?
Solution:
The GIL is a mutex in CPython (the standard Python implementation) that prevents multiple native threads from executing Python bytecode at the same time. This can limit the performance of multithreaded Python programs in CPU-bound operations but not in I/O-bound operations.
Hope it helps :)
