Top 25 Python Interview Questions & Answers

Top 25 Python Interview Questions & Answers

1) What is Python?

Python is an interpreted, high-level and dynamically typed programming language. It is a general purpose programming language which can be used to develop a wide variety of applications. Python syntax is very simple to use and easy to learn which makes it a very popular language.

2) What are the key features of Python?

• Python is an interpreted language which means code is not compiled and directly run.
• Python is dynamically typed language which means each statement is executed line by line and type-checking is done dynamically during execution.
• Python provides all Object Oriented Programming concepts like classes, inheritance, etc.… except access modifiers.
• Python is a cross platform language which means it can be written in one Operating System and run on another OS without making any changes.
• Python can be used across multiple domains like web application development, Data Science, Machine Learning.

3) What is PEP 8?

PEP stands for Python Enhancement Proposal. It is a set of rules that specify how to format Python code for maximum readability.

4) What are the different data types in Python?

• Numbers
• Strings
• Lists
• Tuples
• Dictionaries

5) What is the difference between Lists and Tuples?

• Lists are mutable but Tuples are immutable
• Lists are slower when compared to tuples
• Lists are used to store elements of same data type but tuples can store elements from different data types
• Tuples have fixed length but Lists have variable length

6) Explain about memory management in Python?

Memory is managed by Python private heap space. All Python objects are stored in the private heap space and is inaccessible to the programmers. Python also has an inbuilt garbage collector which recycles all unused memory space.

7) What are namespaces in Python?

Python namespaces are used to make sure that object names are always unique in a program. These namespaces are implemented as dictionaries where the key is name and value is object.

8) What are different modules commonly used in Python?

Modules are reusable Python scripts which can be imported and used in different scripts or codes. It can consist of variables, functions or classes. It helps in making our code more organized, reusable and efficient. Some of the common Python modules are os, sys, math and random.

9) Is Python a case sensitive language?

Yes. Python is case-sensitive language.

10) What is the difference between Python Arrays and Lists?

Arrays can store elements with single data type but Lists can store elements of different data types.

11) How will you delete files in Python?

We can import the “os” module and use remove() function to delete files.

import os
os.remove("sample.txt")

12) How can you open a file for writing in Python?

fi = open("file1.txt","wt")

13) What is lambda function in Python?

Lambda function is an anonymous function in Python. It can accept any number of arguments but only has a single expression.

14) Do we need to declare variables in Python?

No. Python interpreter automatically identifies the data type of a variable based on the type of value assigned to the variable.

15) How to remove all leading whitespaces in a string in Python?

lstrip() function is used to remove all leading whitespaces from a string.

16) What is Docstring in Python?

Docstring is used to provide documentation for different modules, functions, classes and methods in Python.

17) What is the difference between set and dictionary in Python?

• Lists is an ordered collection while Python is a unordered collection of data values
• Lists can hold single values while Python can hold elements as key:value pairs

18) What are Python decorators?

It allows programmers to modify the changes in the behavior of a class or function in Python.

19) What is the difference between .pyc and .py files?

•  .pyc is a compiled bytecode file generated by Python compiler
• .py is the Python source file

20) How can we create a Python function?

Functions can be defined by using the def statement.

def print():

21) What is String slicing in Python?

We can use slicing to select a sub-string from the given string.

String = 'QASCRIPT'
print(String[:2])
Output: QA

It is a special type of method which is called automatically once the memory is allocated for a new object. It is used to initialize the values of instance members for objects.

23) How to reverse a string in Python?

We can reverse a string using the slicing function in Python.

String = 'QASCRIPT'
print(String[::-1])
Output: TPIRCSAQ

We can use remove() or pop() function to remove elements from an array.

lang = ["Java","Python","C"]
//Removes the second element
lang.pop(1)
//Removes the element with value=C 
lang.remove("C")

We can use static analysis tool named PyChecker to find bugs in Python source code. There is another tool called PyLint to check coding standards in Python modules.