Here is a collection of Python interview questions and answers for freshers:
1. What is Python, and why is it popular for programming?
Python is a high-level, interpreted programming language known for its simplicity and readability. It’s popular because of its ease of learning, wide-ranging applications (web development, data analysis, automation), and a large supportive community.
2. Explain the difference between Python 2 and Python 3.
Python 2 and Python 3 are two major versions of Python. Python 3 was introduced to fix and improve certain aspects of Python 2. Key differences include print statements, Unicode support, and integer division.
3. How do you comment in Python?
In Python, you can add comments using the ‘#’ symbol. Comments are ignored by the interpreter and are used for code documentation.
4. What are variables in Python?
Variables are used to store data values. In Python, you don’t need to declare the data type explicitly; the interpreter infers it based on the assigned value.
5. Explain the concept of indentation in Python.
Indentation is crucial in Python; it represents block structure and scope. Proper indentation is necessary for code readability and functionality.
6. What is a Python data type?
Data types in Python define the kind of data a variable can hold. Common data types include int, float, str, and bool.
7. How do you declare and initialize a variable in Python?
Variables in Python can be declared and initialized in one line, for example: x = 10.
8. Explain the difference between ‘==’ and ‘is’ in Python.
‘==’ checks if the values of two variables are equal, while ‘is’ checks if two variables reference the same object in memory.
9. What is a list in Python?
A list is a collection of ordered and mutable elements, enclosed in square brackets. Lists can store data of various data types.
10. How do you access elements in a list?
You can access elements in a list using indexing. Python uses zero-based indexing, so the first element is at index 0.
11. What is a tuple in Python?
A tuple is an ordered and immutable collection of elements, enclosed in parentheses. Tuples are often used when data should not be modified.
12. Explain Python dictionaries.
Dictionaries are collections of key-value pairs, where each key is unique. They are defined with curly braces, e.g., {'name': 'John', 'age': 25}.
13. What is a Python set?
A set is an unordered collection of unique elements. Sets are defined using curly braces or the set() constructor.
14. How do you create a function in Python?
Functions are created using the def keyword followed by the function name, parameters, and a colon. The function body is indented.
15. Explain the ‘if’ statement in Python.
The ‘if’ statement is used for conditional execution. If a condition is true, the indented code block under ‘if’ is executed.
16. What is a ‘for’ loop in Python?
A ‘for’ loop is used to iterate over a sequence (like a list or string) or other iterable objects. It executes a block of code for each item in the sequence.
17. What is the ‘while’ loop in Python?
A ‘while’ loop repeatedly executes a block of code as long as a specified condition is true. It’s used when the number of iterations is uncertain.
18. How do you handle exceptions in Python?
Exceptions are handled using ‘try’ and ‘except’ blocks. Code that might raise an exception is placed in the ‘try’ block, and the ‘except’ block handles the exception gracefully.
19. Explain the concept of modules in Python.
Modules are files containing Python code, which can be reused in other programs. You can import modules using the ‘import’ keyword.
20. What is PIP in Python?
PIP is a package manager for Python, used to install, manage, and uninstall Python packages or libraries from the Python Package Index (PyPI).
21. Describe list comprehensions in Python.
List comprehensions provide a concise way to create lists. They can be used to apply an expression to each item in an iterable.
22. What is a lambda function in Python?
Lambda functions, also known as anonymous functions, are small, unnamed functions defined using the lambda keyword.
23. Explain object-oriented programming (OOP) in Python.
Python supports OOP principles like encapsulation, inheritance, and polymorphism. It allows you to create and work with objects and classes.
24. How do you open and close files in Python?
You can open files using the ‘open()’ function, specifying the file path and mode. To close a file, use the ‘close()’ method.
25. What is the difference between ‘append()’ and ‘extend()’ methods in lists?
‘append()’ adds an element to the end of a list, while ‘extend()’ appends elements of an iterable to the end of the list.
26. What is a decorator in Python?
Decorators are a powerful feature in Python used to modify or enhance the behavior of functions or methods.
27. Explain the Global Interpreter Lock (GIL) in Python.
GIL is a mutex used in CPython (the default Python interpreter) to allow only one thread to execute in the interpreter at a time. This can impact multi-threaded performance in CPU-bound programs.
28. How do you handle file exceptions in Python?
You can use ‘try’, ‘except’, and ‘finally’ blocks to handle file exceptions like FileNotFoundError or IOError gracefully.
29. What is the purpose of the ‘pass’ statement in Python?
The ‘pass’ statement is a placeholder used when syntactically required but no action is desired.
30. How do you import functions or objects from a module?
You can import specific functions or objects from a module using the ‘from’ keyword, followed by the module name and ‘import’ statement.
31. Explain the use of ‘self’ in Python classes.
‘self’ is a reference to the instance of the class. It’s used within class methods to access and modify instance attributes.
32. How do you create a virtual environment in Python?
You can create a virtual environment using the ‘venv’ module. It helps isolate project dependencies from the system Python installation.
33. Describe the purpose of the ‘with’ statement in Python.
The ‘with’ statement is used to simplify file handling. It ensures that the file is properly closed after operations are performed on it.
34. What is the purpose of the ‘init’ method in Python classes?
The ‘init‘ method is a constructor used to initialize object attributes when an instance of a class is created.
35. Explain the use of ‘super()’ in Python classes.
‘super()’ is used to call a method from a parent class. It’s often used to extend the functionality of a parent class method in a child class.
36. What is a generator in Python, and how is it different from a list?
A generator is an iterable that generates values on-the-fly rather than storing them in memory. It’s more memory-efficient than lists, especially for large datasets.
37. How do you handle multiple exceptions in a single ‘except’ block?
You can use a tuple of exceptions in a single ‘except’ block to handle multiple exceptions with the same code.
38. Explain the purpose of the ‘del’ statement in Python.
The ‘del’ statement is used to remove a reference to an object or a specific element from a data structure.
39. What are docstrings in Python, and how are they useful?
Docstrings are triple-quoted strings used for documentation within modules, classes, functions, or methods. They help in code documentation and can be accessed using the ‘help()’ function.
40. What is the Global Variable in Python?
A global variable is a variable defined outside of any function or method. It can be accessed and modified from any part of the program.
41. Explain the ‘try’…’finally’ block in Python.
The ‘try’…’finally’ block is used to ensure that a specific block of code is always executed, whether an exception is raised or not. It’s often used for resource cleanup.
42. How can you remove duplicates from a list in Python?
You can remove duplicates from a list by converting it to a set (which automatically removes duplicates) and then back to a list.
43. What is the purpose of the ‘enumerate()’ function in Python?
The ‘enumerate()’ function is used to iterate over elements of an iterable while keeping track of the index or position of each element.
44. Explain the ‘map()’ function in Python.
The ‘map()’ function applies a given function to all items in an input list and returns a new list with the results.
45. What is the purpose of the ‘filter()’ function in Python?
The ‘filter()’ function filters elements of an iterable based on a given function, returning a new iterable with the filtered results.
46. Describe a Python decorator and its use cases.
A Python decorator is a function that modifies another function or method’s behavior. It is often used for tasks like logging, authentication, and access control.
47. How do you handle an ‘ImportError’ in Python?
An ‘ImportError’ occurs when Python cannot locate a module or package. You can handle it using ‘try’…’except’ blocks or by ensuring the module is installed.
48. Explain the ‘assert’ statement in Python.
The ‘assert’ statement is used for debugging. If the given expression is False, it raises an ‘AssertionError’ with an optional error message.
49. How can you reverse a list in Python?
You can reverse a list using the ‘reverse()’ method or by slicing the list with a step of -1.
50. What is the purpose of the ‘pass’ statement in Python loops?
The ‘pass’ statement is a placeholder that does nothing. It’s often used to create empty loops or conditional statements.
These questions and answers should help you prepare for Python interviews as a fresher. Remember to practice coding exercises and explore real-world projects to solidify your Python skills further. Good luck with your interviews!