This repository contains 100 Python Interview Questions divided into Easy, Intermediate, and Hard sections. These questions cover the core concepts and help you prepare for Python-related interviews.
| # | Question | Answer |
|---|---|---|
| 1 | What is Python? | Python is a high-level, interpreted, general-purpose programming language. |
| 2 | What are Python's key features? | Interpreted, dynamically-typed, object-oriented, and has a vast standard library. |
| 3 | How do you create a variable in Python? | By assigning a value to it (e.g., x = 10). |
| 4 | How do you write comments in Python? | Using the # symbol for single-line comments, or triple quotes ''' for multi-line comments. |
| 5 | What is a function in Python? | A reusable block of code that performs a specific task, defined using the def keyword. |
| 6 | What is the difference between a list and a tuple in Python? | A list is mutable, whereas a tuple is immutable. |
| 7 | How do you create a list in Python? | By placing elements within square brackets: my_list = [1, 2, 3]. |
| 8 | How do you create a tuple in Python? | By placing elements within parentheses: my_tuple = (1, 2, 3). |
| 9 | How do you create a dictionary in Python? | Using curly braces with key-value pairs: my_dict = {'a': 1, 'b': 2}. |
| 10 | How do you create a set in Python? | By placing elements within curly braces: my_set = {1, 2, 3}. |
| 11 | How do you check the type of an object in Python? | Using the type() function. |
| 12 | What is the difference between == and is operators? |
== checks value equality, whereas is checks identity (whether two objects are the same in memory). |
| 13 | How do you handle exceptions in Python? | Using try, except, finally blocks. |
| 14 | What is the purpose of the range() function? |
To generate a sequence of numbers. |
| 15 | How do you concatenate strings in Python? | Using the + operator or join() method. |
| 16 | What are Python's built-in data types? | int, float, str, list, tuple, set, dict, bool. |
| 17 | How do you define a class in Python? | Using the class keyword followed by the class name and a colon. |
| 18 | What is an instance in Python? | An object created from a class. |
| 19 | What is the difference between local and global variables in Python? | Local variables are defined within a function, whereas global variables are defined outside any function. |
| 20 | How do you import a module in Python? | Using the import statement (e.g., import math). |
| # | Question | Answer |
|---|---|---|
| 21 | What is list comprehension in Python? | A concise way to create lists using a single line of code. |
| 22 | How do you perform list comprehension? | [expression for item in iterable]. |
| 23 | What is the map() function in Python? |
Applies a function to every item of an iterable and returns an iterator. |
| 24 | What is the filter() function in Python? |
Filters items from an iterable based on a function and returns an iterator. |
| 25 | What is the difference between map() and filter()? |
map() applies a function to each element, while filter() removes elements that don’t meet a condition. |
| 26 | How do you use the reduce() function? |
By applying a function cumulatively to items in an iterable to reduce it to a single value (requires functools). |
| 27 | What is a lambda function? | An anonymous, inline function defined using the lambda keyword. |
| 28 | What is the difference between None and False in Python? |
None represents the absence of a value, while False is a boolean value. |
| 29 | How do you reverse a list in Python? | Using list.reverse() or reversed(list). |
| 30 | How do you create a generator in Python? | Using a function with yield instead of return. |
| 31 | What is the with statement used for? |
It simplifies exception handling by encapsulating common preparation and cleanup tasks. |
| 32 | How do you handle files in Python? | Using open(), read(), write(), and close() methods. |
| 33 | How do you sort a list of dictionaries by a key? | By using the sorted() function with a key argument. |
| 34 | How do you merge two dictionaries in Python? | Using the update() method or {**dict1, **dict2}. |
| 35 | What is the purpose of the zip() function? |
To combine two or more iterables into tuples. |
| 36 | How do you check if a key exists in a dictionary? | Using the in operator (e.g., if key in my_dict). |
| 37 | What is the del statement used for? |
To delete objects, variables, list elements, or dictionary keys. |
| 38 | What is the difference between deep copy and shallow copy? | A deep copy copies all objects recursively, while a shallow copy copies only the top-level object. |
| 39 | What is the purpose of the enumerate() function? |
It adds a counter to an iterable and returns it as an enumerate object. |
| 40 | How do you create an infinite loop in Python? | By using while True: without a breaking condition. |
| 41 | What is the purpose of the global keyword? |
To declare that a variable inside a function refers to a globally defined variable. |
| 42 | How do you remove duplicates from a list? | By converting the list into a set and back into a list: list(set(my_list)). |
| 43 | How do you convert a list of strings to integers? | Using list comprehension with int() function: [int(x) for x in my_list]. |
| 44 | What is the difference between sort() and sorted()? |
sort() sorts a list in-place, while sorted() returns a new sorted list. |
| 45 | How do you handle JSON data in Python? | Using the json module to load(), dump(), loads(), and dumps(). |
| 46 | How do you create a virtual environment in Python? | Using the venv module: python -m venv env_name. |
| 47 | How do you check for memory leaks in Python? | By using tools like gc module or memory_profiler. |
| 48 | What is the __name__ variable in Python? |
It holds the name of the current module. If the module is being run directly, it will be '__main__'. |
| 49 | What is a decorator in Python? | A function that modifies the behavior of another function or method. |
| 50 | How do you create a decorator? | By defining a function that returns another function, using the @ symbol before the function name. |
| # | Question | Answer |
|---|---|---|
| 51 | What is the Global Interpreter Lock (GIL)? | A mutex that protects access to Python objects, preventing multiple threads from executing Python bytecodes simultaneously. |
| 52 | How do you implement multithreading in Python? | Using the threading module to create and manage threads. |
| 53 | How do you handle multiprocessing in Python? | Using the multiprocessing module to create and manage processes. |
| 54 | What are metaclasses in Python? | Metaclasses are classes of classes that define how classes are created and behave. |
| 55 | How do you create a metaclass? | By defining a class that inherits from type. |
| 56 | What is monkey patching? | The dynamic modification of a class or module at runtime. |
| 57 | How do you implement method overloading in Python? | Python does not natively support method overloading. You can implement it using default arguments or variable-length arguments. |
| 58 | What is method overriding? | Redefining a method in a subclass that was originally defined in the parent class. |
| 59 | How does Python's garbage collection work? | Python uses reference counting along with a cyclic garbage collector to free memory. |
| 60 | How do you use asyncio in Python? |
By using async def to define coroutines and await to yield control during blocking operations. |
| 61 | What is a coroutine? | A coroutine is a function that can pause its execution and return control to the event loop, resuming later. |
| 62 | How do you handle exceptions in asynchronous code? | Using try and except blocks inside async functions or handling exceptions in the event loop. |
| 63 | How do you profile Python code performance? | By using modules like cProfile and timeit to measure execution time and performance bottlenecks. |
| 64 | What is a closure in Python? | A closure is a function that remembers the values from its lexical scope even when the program flow is no longer in that scope. |
| 65 | What is the nonlocal keyword? |
It allows a function to modify variables from the nearest enclosing scope that is not global. |
| 66 | What is functools.lru_cache? |
A decorator that caches the results of function calls to improve performance. |
| 67 | What is duck typing in Python? | Duck typing refers to Python's dynamic typing, where an object's suitability is determined by its methods and properties rather than its type. |
| 68 | How do you manage memory in Python? | By avoiding circular references, using weak references, and monitoring object lifetimes. |
| 69 | What is a weak reference in Python? | A weak reference allows one to reference an object without preventing its garbage collection. |
| 70 | How do you serialize and deserialize objects in Python? | By using the pickle module to convert objects to byte streams and back. |
| 71 | What is a context manager in Python? | A context manager allows setup and cleanup operations around a block of code using with statements. |
| 72 | How do you create a custom context manager? | By defining a class with __enter__ and __exit__ methods or using the contextlib module. |
| 73 | What is the dataclasses module in Python? |
It provides a decorator and functions for automatically adding special methods to user-defined classes. |
| 74 | How do you enforce immutability in Python? | By using namedtuple, frozenset, or custom classes with overridden setters. |
| 75 | What are slots in Python? | Slots are a mechanism to restrict dynamic attribute creation in objects by using the __slots__ attribute in a class. |
| 76 | What is the difference between @staticmethod and @classmethod? |
@staticmethod defines a method that doesn't access the instance or class, while @classmethod takes a cls argument that refers to the class. |
| 77 | How do you perform type hinting in Python? | By specifying the expected types of function arguments and return values using annotations. |
| 78 | How do you implement singleton design pattern in Python? | By using a metaclass or overriding the __new__ method. |
| 79 | What are Python descriptors? | Descriptors are objects that manage the attributes of other objects through methods like __get__, __set__, and __delete__. |
| 80 | How do you use property() in Python? |
To create getter, setter, and deleter methods for class attributes. |
| 81 | What is the Observer design pattern in Python? | A pattern where an object (subject) notifies observers (listeners) about changes. |
| 82 | How do you create threads in Python? | Using the threading module by creating Thread objects. |
| 83 | What is a deadlock in Python? | A situation where two or more threads are blocked forever, waiting for each other to release resources. |
| 84 | How do you prevent deadlocks in Python? | By using locks, semaphores, or avoiding circular waits. |
| 85 | What is the difference between a thread and a process? | A thread is a lightweight process that shares memory space, while a process has its own memory space. |
| 86 | How do you use heapq in Python? |
By using the heapq module to implement a priority queue with a heap. |
| 87 | What is memoization in Python? | A technique to store function call results to avoid recalculating for the same inputs. |
| 88 | How do you dynamically load a module in Python? | By using importlib.import_module(). |
| 89 | What is reflection in Python? | The ability of a program to inspect and modify its structure and behavior at runtime. |
| 90 | How do you get the name of the currently executing function in Python? | Using inspect.currentframe().f_code.co_name. |
| 91 | How do you create an abstract base class in Python? | By importing ABC from the abc module and using @abstractmethod decorator. |
| 92 | What is the Chain of Responsibility design pattern? | A pattern where requests are passed along a chain of handlers until one handles it. |
| 93 | What is method resolution order (MRO)? | The order in which Python looks up methods in a class hierarchy, used in multiple inheritance. |
| 94 | How do you achieve multiple inheritance in Python? | By specifying multiple base classes in a class definition. |
| 95 | What is a metaclass conflict in Python? | It occurs when a class inherits from two classes with incompatible metaclasses. |
| 96 | How do you detect circular dependencies in Python? | Using tools like pydeps or by manually inspecting the module import graph. |
| 97 | How do you implement the State design pattern in Python? | By creating a state base class and specific state subclasses, switching states dynamically. |
| 98 | What is the purpose of super() in Python? |
To call methods from a parent class in a subclass, typically during method overriding. |
| 99 | How do you make Python code faster? | By using tools like Cython, optimizing loops, using numpy, and reducing function calls. |
| 100 | How do you deal with memory fragmentation in Python? | By avoiding large object allocations and using pymalloc or memory profilers to manage memory efficiently. |
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