Top 50 Python Interview Questions with Answers 2024

Looking to ace your Python interview in 2024? Check out our comprehensive list of the top 50 Python interview questions with detailed answers.

Basic Python Interview Questions:

1. What is Python?

   • Python is a high-level, interpreted, and general-purpose programming language. It emphasizes code readability and has a simple and easy-to-learn syntax.

2. What are the key features of Python?

   • Key features of Python include its simplicity, readability, versatility, and the large standard library it offers. It supports multiple programming paradigms, such as procedural, object-oriented, and functional programming.

3. What is PEP 8?

   • PEP 8 is a style guide for Python code. It provides guidelines for writing clean, readable code and covers topics such as naming conventions, code layout, and programming practices.

4. What is the difference between Python 2 and Python 3?

   • Python 3 is the latest version of the Python programming language and is not backward compatible with Python 2. Python 3 introduces several new features and syntax changes, including the print() function, Unicode support, and syntax for function annotations.

5. What is the difference between list and tuple in Python?

   • Lists are mutable, ordered collections of items, whereas tuples are immutable, ordered collections. Lists are defined using square brackets [], while tuples are defined using parentheses ().

6. Explain Python dictionaries.

   • Dictionaries in Python are unordered collections of key-value pairs. They are defined using curly braces {} and are mutable. Each key in a dictionary must be unique.

7. What is the difference between == and is in Python?

   • The == operator is used to compare the values of two objects, while the is operator is used to compare the identities of two objects. In other words, == checks for equality, whereas is checks for identity.

8. Explain the terms "mutable" and "immutable" and give examples.

   • Mutable objects can be changed after they are created, while immutable objects cannot. Examples of mutable objects in Python include lists, dictionaries, and sets, while examples of immutable objects include tuples, strings, and numbers.

9. What is a generator in Python?

   • A generator in Python is a special type of iterator that generates values on-the-fly using the yield keyword. Generators are memory efficient and can be used to iterate over large sequences without storing them in memory.

10. Explain the term "duck typing".

    • Duck typing is a programming concept in which the type or class of an object is less important than the methods and properties it defines. In duck typing, an object's suitability for a particular purpose is determined by whether it supports the necessary methods and properties, rather than its type or class.

Python Data Types and Data Structures:

11. What are the basic data types in Python?

    • Basic data types in Python include integers, floating-point numbers, complex numbers, strings, booleans, and the None object.

12. Explain the concept of slicing in Python.

    • Slicing is a way to extract a portion of a sequence (such as a string, list, or tuple) in Python. It is done using the square bracket notation [] and allows you to specify a start index, stop index, and step size.

13. How can you convert a string to a number in Python?

    • You can convert a string to a number in Python using the int(), float(), or complex() functions, depending on the type of number you want to convert the string to.

14. Explain the difference between append() and extend() methods for lists.

    • The append() method adds a single element to the end of a list, while the extend() method adds multiple elements to the end of a list by appending all the elements of an iterable (such as another list) to the end of the list.

15. What is the difference between remove() and pop() methods for lists?

    • The remove() method removes the first occurrence of a specified value from a list, while the pop() method removes the element at a specified index and returns it.

16. Explain the difference between a shallow copy and a deep copy.

    • A shallow copy creates a new object that references the original object, while a deep copy creates a new object and recursively copies all the objects that the original object references.

17. What is a Python set? How is it different from a list or a tuple?

    • A set in Python is an unordered collection of unique elements. Unlike lists and tuples, sets do not allow duplicate elements, and they are not ordered.

18. Explain the difference between a list and a set.

    • Lists are ordered collections of elements that allow duplicates, while sets are unordered collections of unique elements that do not allow duplicates.

19. Explain the difference between a list and a dictionary.

    • Lists are ordered collections of elements that are indexed by integers, while dictionaries are unordered collections of key-value pairs that are indexed by keys.

20. Explain the concept of a dictionary comprehension.

    • A dictionary comprehension is a concise way to create dictionaries in Python. It allows you to create dictionaries using a single line of code by specifying key-value pairs and an optional condition.

Python Control Flow and Functions:

21. What is the purpose of the pass statement in Python?

    • The pass statement in Python is a null statement that does nothing. It is used as a placeholder where a statement is required syntactically but no action is needed.

22. What is a lambda function in Python?

    • A lambda function in Python is a small, anonymous function that can have any number of parameters but can only have one expression. Lambda functions are often used as arguments to higher-order functions.

23. Explain the difference between map() and filter() functions.

    • The map() function applies a given function to each item of an iterable and returns a list of the results, while the filter() function filters an iterable based on a given function and returns a list of the items for which the function returns True.

24. What is a decorator in Python?

    • A decorator in Python is a design pattern that allows you to add functionality to an existing function or method without modifying its code. Decorators are implemented using the @ symbol followed by the decorator function.

25. Explain the concept of *args and kwargs.

    • *args and **kwargs are special syntax in Python that allow a function to accept a variable number of positional arguments and keyword arguments, respectively. *args collects extra positional arguments as a tuple, while **kwargs collects extra keyword arguments as a dictionary.

26. What is recursion in Python? Give an example.

    • Recursion is a programming technique in which a function calls itself in order to solve smaller instances of the same problem. Here's an example of a recursive function to calculate the factorial of a number:

      def factorial(n):
          if n == 0:
              return 1
          else:
              return n * factorial(n-1)
      

       

27. What is the purpose of the global keyword in Python?

    • The global keyword in Python is used inside a function to indicate that a variable should be treated as a global variable, rather than a local variable.

28. What is the purpose of the nonlocal keyword in Python?

    • The nonlocal keyword in Python is used inside a nested function to indicate that a variable should be treated as a nonlocal variable, rather than a local variable or a global variable.

29. Explain the difference between == and != operators with respect to the __eq__() and __ne__() methods.

    • The == operator checks for equality and calls the __eq__() method, while the != operator checks for inequality and calls the __ne__() method. These methods can be overridden in custom classes to define custom equality behavior.

30. Explain the purpose of __init__() method in Python.

    • The __init__() method is a special method in Python classes that is called when a new instance of the class is created. It is used to initialize the attributes of the object.

Object-Oriented Programming (OOP) in Python:

31. What is OOP?

    • Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data (in the form of attributes) and code (in the form of methods). OOP allows for the modular and reusable design of software.

32. Explain the four principles of OOP.

    • The four principles of object-oriented programming are:
      • Encapsulation: The bundling of data and methods that operate on that data into a single unit (i.e., a class).
      • Inheritance: The ability to create new classes based on existing classes.
      • Polymorphism: The ability for different classes to be treated as instances of the same class through inheritance.
      • Abstraction: The process of hiding the implementation details of a class and exposing only the necessary features.

33. What is a class in Python?

    • A class in Python is a blueprint for creating objects. It defines the attributes (data) and methods (functions) that all instances of the class will have.

34. What is an object in Python?

    • An object in Python is an instance of a class. It contains data (in the form of attributes) and code (in the form of methods) that operate on that data.

35. Explain the concept of inheritance in Python.

    • Inheritance is a feature of object-oriented programming that allows you to define a new class based on an existing class. The new class (called a subclass or derived class) inherits the attributes and methods of the existing class (called a superclass or base class).

36. What is method overriding in Python?

    • Method overriding is the process of defining a method in a subclass that has the same name and signature as a method in the superclass. The method in the subclass "overrides" the method in the superclass, providing a new implementation.

37. What is method overloading in Python?

    • Method overloading is the ability to define multiple methods with the same name but different signatures in a class. Python does not support method overloading directly, but you can achieve similar behavior using default argument values or variable-length argument lists.

38. What is encapsulation in Python?

    • Encapsulation is the bundling of data and methods that operate on that data into a single unit (i.e., a class). It allows you to control access to the data by defining the data as private and providing public methods to access and modify the data.

39. What is polymorphism in Python?

    • Polymorphism is the ability for different classes to be treated as instances of the same class through inheritance. It allows you to write code that can operate on objects of different classes without needing to know the specific class of each object.

40. What is the purpose of self in Python?

    • self is a reference to the current instance of a class. It is used inside a class to access the attributes and methods of the class's instances.

Exception Handling and File Handling in Python:

41. What is exception handling in Python?

    • Exception handling is the process of responding to and recovering from exceptions (errors) that occur during the execution of a program. It allows you to write code that gracefully handles errors and prevents the program from crashing.

42. Explain the try, except, finally blocks.

    • The try block is used to enclose the code that may raise an exception. The except block is used to handle the exception if it occurs. The finally block is used to execute code that should always run, regardless of whether an exception occurs.

43. What is the purpose of the else block in exception handling?

    • The else block in exception handling is executed if the try block does not raise an exception. It is typically used to execute code that should run only if no exception occurs.

44. What is the purpose of the raise statement in Python?

    • The raise statement in Python is used to raise an exception manually. It allows you to create custom exceptions and signal errors in your code.

45. Explain the concept of file handling in Python.

    • File handling in Python allows you to read from and write to files. It involves opening a file, performing read or write operations, and then closing the file.

46. What is the difference between reading a file in 'r' mode and 'rb' mode?

    • When reading a file in 'r' mode, the file is opened in text mode and returns strings, while when reading a file in 'rb' mode, the file is opened in binary mode and returns bytes.

47. How can you write to a file in Python?

    • You can write to a file in Python using the write() method. If the file is opened in text mode, you can write strings to the file, and if the file is opened in binary mode, you can write bytes to the file.

48. Explain the purpose of with statement in file handling.

    • The with statement in Python is used to open a file and ensure that it is closed properly after the block of code inside the with statement is executed. It is a context manager that automatically handles the opening and closing of the file.

49. What is the difference between read() and readline() methods?

    • The read() method reads the entire contents of a file as a single string or bytes object, while the readline() method reads a single line from the file and returns it as a string or bytes object.

50. How can you iterate over lines of a file in Python?

    • You can iterate over the lines of a file in Python using a for loop. Each iteration of the loop reads a single line from the file until the end of the file is reached.