Register Login

Top 20 Python Interview Questions and Answers

Python has become by far the most widely used general-purpose programming language. Choosing Python during your career development will give you a lucrative career. If you look for one of the best programming languages used by any company, Python will be among the top 3 in the list. In this article, you will learn about the top 20 Python interview questions.

1. Mention some popular applications of Python.

Ans: Python is the most well-accepted, general-purpose, high-level programming language created by Guido van Rossum. This highly readable programming language allows programmers to write the instructions for developing programs and applications for:

  • Web Development
  • Software Development
  • Data science
  • System Scripting
  • Complex Mathematics
  • Game Development

2. What is the difference between Tuple and List in Python?

Ans: Both of them help in storing heterogeneous values. But they have a distinction between them.

Tuple List
Tuple is immutable List is mutable
Iteration operation is comparatively fast in Tuple Iteration operation is comparatively slower than Tuple in List
Tuple requires less memory than List List requires more memory than Tuple
It has fewer built-in methods It has a huge collection of built-in methods
Appending data is not possible Appending data in list can be done easily using the append() method
Tuple is appropriate in developing applications where data accessing operation is done frequently List is preferred in building application where frequent data insertion and deletion takes place
Tuple’s storage mechanism is static in nature List’s storage mechanism is dynamic in nature

3. What is PYTHONPATH?

PYTHONPATH is an environment variable that helps when a module needs to be imported into a Python program. When a programmer needs to import a module, PYTHONPATH acts as a look-up for checking for the presence of the imported modules on those paths or directories. The Python interpreter utilizes it to detect the path and resolve which module to load.

4. How Python does memory management?

Ans: Most of the Python objects are dynamic in nature. So, Python uses its private heap space for managing the object and its memory. All the Python objects and data structures get stored in the primary memory's heap space. Even the programmer does not have the privilege to access these private spaces as the interpreter has access restrictions to them. Python also provides its own inbuilt garbage collector that can recycle all its unused memory and releases the memory to make it free to the heap space for other storage and uses.

5. What are positive and negative indices in Python?

Ans: There are two different ways of representing an object index in Python. These are

  • positive index and
  • negative index

The positive index starts from 0 up to n-1, whereas the negative index starts from -1 and goes up to -n. When programmers apply the positive indices, the searching beings from left to the right. When programmers apply the negative indices, the searching begins from right to left.

6. What is the use of a pass statement in Python?

Ans: Pass statement is a null statement that does not perform anything. The pass statement uses the pass keyword that acts as a placeholder and instructs the compiler not to do anything. It is implemented when the programmer doesn’t want any code to execute. So, programmer simply uses the pass there as empty code within function definitions, loops, decision-making statement body, class definitions, or in other blocks or suits.

7. Tell me some differences between Python 2.x and Python 3.x.

Ans: There are many significant differences between both versions.

  • In Python 2.x, for printing anything in the console output, the print keyword was used. This print keyword got replaced by the print() function in Python 3.x.
  • In Python 2.x, all the implicit string type has its base character set as ASCII. But in Python 3.x, all the implicit string type has its character set as Unicode.
  • There is no xrange() in Python 3.x, whereas there is no range() in Python 2.x.

8. What are Python Iterators?

Ans: Python iterators help in iterating any object containing a collection of elements. Iterators are the group of items, which can be implemented on any iterable object like lists, tuples, or dictionaries. The iterator in Python implements __itr__ and the next() method for iterating the stored elements. Python iterator generally implements the loops for iterating over the collections (lists and tuples).

9. What is the use of break statements in Python?

Ans: The break statement aid to control or terminate the Python loop by separating the current loop from executing and jump out to transfer the control to the subsequent block.

10. Is Python case sensitive?

Ans: Yes, Python is a case-sensitive programming language. It means anything you type as an identifier or keyword has a sensitive case (uppercase or lowercase). If you type:

var = 10


Var = 10,

both are two different Python objects allocating two different memory locations.

11. What are Lambda functions in Python?

Ans: Lambda functions are anonymous functions that can have n number of parameters associated with them. But it should have only one statement.

For example

z = lambda a, b, c, d : a + b + c + d
print( z(7, 3, 8, 2))

12. What is the use of the def keyword?

Ans: The def keyword helps in creating or defining a user-defined function in Python. We have to use the keyword def followed by the name of the function and pass the parameters (if any) within the parenthesis.

13. What are the different ways of representing strings?

Ans: The string is a popular compound data type that acts as an iterable object. There are four different ways of representing strings in Python.

  • Using a pair of single quotes ''
  • Using a pair of double quotes ""
  • Using a pair of single quotes three-times ''' '''
  • Using a pair of double quotes three-times """ """

14. What is type conversion?

Ans: Type conversion is converting a valid Python object from one type to the other. Python supports two different types of type conversion.

  • Implicit type casting
  • Explicit type casting

In the case of implicit typecasting, type conversion takes place automatically by the Python interpreter.
In the case of explicit typecasting, type conversion has to be done by the programmer using the predefined functions like int(), float(), ord(), dict(), list(), tuple(), etc.

15. Mention the names of some ways through which you can perform a reverse of a string.

  • Using Loop
  • Using recursion
  • Negative indexing
  • Using the stack data structure
  • Extended Slice Syntax

16. What is the main purpose of the relational operator?

Ans: The main purpose of the relational operator is to compare values or operands and return either true or false based on the resultant expression.

17. What is the use of # in Python?

Ans: The # is used to comment everything associated with it in the same line. Once commented, the Python interpreter will automatically ignore anything written within it.

18. What are Python modules?

Ans: Python modules are set of statements and definitions containing within a file. Such a module also contains runnable code, or similar codes that can help makes the code easier to understand & implement. Programmers can reuse those codes by importing them into the program they are writing.

19. Does Python have classes and objects?

Ans: Yes, Python has classes and objects. It supports object-oriented programming.

20. What is a nesting of a list?

Ans: Creating or declaring a List object within another list is called the nesting of a list. Let suppose, you have a variable li. Then we can create a collection of lists within the li list.

E.g., li = [[2, 4, 5], [10, 13, 25]], where [2, 4, 5] is a list and [10, 13, 25] are nested lists residing within the li object.

Before going through the interview question, you must be thorough about the various Python concepts that you can learn from Python Tutorials. The popularity of Python is growing exponentially and is not going anywhere in the next 8 to 9 decades.