Python
Basic Python Interview Questions and Answers
1. What is Python?
Python is an interpreted, high-level, dynamically typed programming language. It is widely used for web development, data analysis, artificial intelligence, scientific computing, and automation.
2. What are the key features of Python?
The key features of Python include:
- Easy-to-read syntax
- Dynamically typed
- Interpreted language
- Large standard library
- Object-oriented
- Extensive support for integration with other languages
- Cross-platform compatibility
3. What are the different data types in Python?
Python supports the following built-in data types:
- Numeric Types: int, float, complex
- Sequence Types: list, tuple, range
- Text Type: str
- Mapping Type: dict
- Set Types: set, frozenset
- Boolean Type: bool
- Binary Types: bytes, bytearray, memoryview
- None Type: None
4. What is the difference between a list and a tuple in Python?
The main difference between a list and a tuple is:
- List: A list is mutable, meaning its elements can be changed or modified after it is created.
- Tuple: A tuple is immutable, meaning once it is created, its elements cannot be modified.
5. What is a dictionary in Python ?
A dictionary in Python is a collection of key-value pairs. It is unordered and mutable. Keys must be unique and immutable (e.g., strings, numbers, or tuples).
6. What is a function in Python?
A function in Python is a block of reusable code that performs a specific task. It is defined using the def keyword, followed by the function name and parameters.
7. What is a functions in Python?
A function in Python is a block of reusable code that performs a specific task. It is defined using the def keyword, followed by the function name and parameters.
8. What is a lambda function in Python?
A lambda function is an anonymous function defined using the lambda keyword. It is used for creating small, one-line functions without a name.
# Example of a lambda function
add = lambda x, y: x + y
print(add(2, 3)) # Output: 5
9. What is the difference between deepcopy() and copy() in Python?
The copy() method creates a shallow copy of an object, meaning that nested objects are not copied and are shared between the original and copied objects. The deepcopy() method creates a deep copy, where all objects are recursively copied, ensuring no shared references between the original and copied objects.
10. What are modules and packages in Python?
A module in Python is a file containing Python code, including functions, classes, and variables. A package is a collection of related modules grouped together in a directory.
11. What is the purpose of the self keyword in Python?
The self keyword is used in instance methods in Python to refer to the instance of the class. It allows access to the class's attributes and methods from within the class.
12. What are Python decorators?
Decorators are functions that modify the behavior of other functions or classes. They are applied using the @decorator_name syntax before the function definition.
13. What are the different types of loops in Python?
Python supports the following types of loops:
- for loop: Used to iterate over a sequence (e.g., list, tuple, string).
- while loop: Repeats as long as a condition is true.
14. What is a generator?
A generator is a function that returns an iterator. It uses the yield keyword to produce values one at a time, instead of returning all values at once, which makes it memory-efficient for large data sets.
15. What is exception handling in Python?
Exception handling in Python is done using try, except, else, and finally blocks to handle runtime errors gracefully. The except block handles the exception, the else block executes if no exceptions occur, and the finally block executes regardless of whether an exception occurs.
16. What are the types of exceptions in Python?
Some common types of exceptions in Python include:
- IndexError: Raised when trying to access an element in a list using an invalid index.
- KeyError: Raised when trying to access a dictionary with a non-existent key.
- ValueError: Raised when a function receives an argument of the correct type but inappropriate value.
- TypeError: Raised when an operation is performed on an object of an inappropriate type.
17. What is list comprehension in Python?
List comprehension is a concise way to create lists by applying an expression to each item in an iterable. It can be more compact and readable than using loops.
# Example of list comprehension
numbers = [x for x in range(10) if x % 2 == 0]
print(numbers) # Output: [0, 2, 4, 6, 8]
18. What is a context manager in Python?
A context manager is a type of object that defines the runtime context for a block of code. It is typically used with the with statement and is useful for managing resources like file handling, database connections, etc.
19. What is the Global Interpreter Lock (GIL) in Python?
The Global Interpreter Lock (GIL) is a mechanism used in CPython to ensure that only one thread executes Python bytecode at a time. This prevents issues with memory management but also limits the effectiveness of multi-threading in Python for CPU-bound tasks.
20. What is the difference between is and == in Python?
The == operator compares the values of two objects, whereas the is operator checks if two references point to the same object in memory.
21. How do you handle file I/O in Python?
File I/O in Python is done using the built-in open() function, followed by methods like read(), write(), or close(). The with statement is often used to ensure that files are properly closed after use.
22. What is multithreading in Python?
Multithreading in Python allows multiple threads to run concurrently within the same process. It is useful for I/O-bound tasks but may not provide a performance boost for CPU-bound tasks due to the Global Interpreter Lock (GIL).
23. What are iterators?
Iterators are objects in Python that allow you to traverse through all the elements of a collection (e.g., list, tuple, etc.). An iterator implements two methods: __iter__() and __next__(). The __next__() method retrieves the next item in the sequence, while __iter__() is used to return the iterator object itself.
24. What are Python's built-in data structures?
Python's built-in data structures include:
- Lists: Ordered, mutable collection of items.
- Tuples: Ordered, immutable collection of items.
- Sets: Unordered collection of unique items.
- Dictionaries: Collection of key-value pairs.
25. What is the purpose of the pass statement in Python?
The pass statement is a null operation in Python. It is used as a placeholder for future code, especially when a statement is syntactically required but you don’t want to add any code. For example, in empty classes, functions, or loops.
# Example of using pass
def function_that_does_nothing():
pass
