Most Popular Python Interview Questions and Answers to Crack any Interview Successfully.
This article provides details on most frequently asked interview questions and answers on Python.
It covers most of the concepts, features and also has some questions directed towards the application of concepts and features. With this Q&A list, you would be able to prepare for any Python theoretical interview.
Top Python Interview Questions and Answers
Enlisted below are the most commonly asked interview questions and answers on Python.
Q #1) Can Python be used for web client and web server side programming? And which one is best suited to Python?
Answer: Python is best suited for web server-side application development due to its vast set of features for creating business logic, database interactions, web server hosting etc.
However, Python can be used as a web client-side application which needs some conversions for a browser to interpret the client side logic. Also, note that Python can be used to create desktop applications which can run as a standalone application such as utilities for test automation.
Answer: Enlisted below are some of the benefits of using Python.
- Application development is faster and easy.
- Extensive support of modules for any kind of application development including data analytics/machine learning/math-intensive applications.
- Excellent support community to get your answers.
Q #3) Explain List, Tuple, Set, and Dictionary and provide at least one instance where each of these collection types can be used.
- List: Collection of items of different data types which can be changed at run time.
- Tuple: Collection of items of different data types which cannot be changed. It only has read-only access to the collection. This can be used when you want to secure your data collection set and does not need any modification.
- Set: Collection of items of the similar data type.
- Dictionary: Collection of items with key-value pairs.
Generally, List and Dictionary are extensively used by programmers as both of them provide flexibility in data collection.
Q #4) Does Python allow you to program in a structured style?
Answer: Yes. It does allow to code is a structured as well as Object-oriented style. It offers excellent flexibility to design and implement your application code depending on the requirements of your application.
Q #5) What is PIP software in the Python world?
Answer: PIP is an acronym for Python Installer Package which provides a seamless interface to install various Python modules. It is a command line tool which can search for packages over the internet and install them without any user interaction.
Q #6) What should be the typical build environment for Python based application development?
Answer: You just need to install Python software and using PIP, you can install various Python modules from the open source community.
For IDE, Pycharm is highly recommended for any kind of application development with vast support for plugins. Another basic IDE is called a RIDE and is a part of the Python open source community.
Q #7) What tools can be used to unit test your Python code?
Answer: The best and easiest way is to use ‘unittest' python standard library to test units/classes. The features supported are very similar to the other unit testing tools such as JUnit, TestNG.
Q #8) How does For loop and While loop differ in Python and when do you choose to use them?
Answer: For loop is generally used to iterate through the elements of various collection types such as List, Tuple, Set, and Dictionary.
While loop is the actual looping feature that is used in any other programming language. This is how Python differs in handling loops from the other programming languages.
Q #9) How are data types defined in Python and how much bytes do integer and decimal data types hold?
Answer: In Python, there is no need to define a variable's data type explicitly.
Based on the value assigned to a variable, Python stores the appropriate data type. In the case of numbers such as Integer, Float, etc, the length of data is unlimited.
Q #10) How do you make use of Arrays in Python?
Answer: Python does not support Arrays. However, you can use List collection type which can store an unlimited number of elements.
Q #11) How do you implement JSON given that Python is best suited for server-side application?
Answer: Python has built-in support to handle JSON objects.
You just have to import the JSON module and use the functions such as loads and dumps to convert from JSON string to JSON object and vice versa. It is a straightforward way to handle and exchange JSON based data from the server-side.
Q #12) What is the best way to parse strings and find patterns in Python?
Answer: Python has built-in support to parse strings using Regular expression module. Import the module and use the functions to find a sub-string, replace a part of a string, etc.
Q #13) Which databases are supported by Python?
Answer: MySQL (Structured) and MongoDB (Unstructured) are the prominent databases that are supported natively in Python. Import the module and start using the functions to interact with the database.
Q #14) What is the purpose of _init_() function in Python?
Answer: It is the first function that gets executed when an object of a class is instantiated. This is equivalent to the constructor concept in C++.
Q #15) What is the significance of ‘self' parameter in an object method? Should we always name this parameter as ‘self'?
Answer: Parameter ‘self' is used to refer to the object properties of a class.
‘self' parameter is supposed to be prefixed to the class object properties. The answer to the second part of the question is No. ‘self' parameter can have any name.
Q #16) How does Lambda function differ from a normal function in Python?
Answer: Lambda is similar to the inline function in C programming. It returns a function object. It contains only one expression and can accept any number of arguments.
In case of a normal function, you can define a function name, pass parameter and mandatorily have a return statement. The Lambda function can be typically used for simple operations without the use of function names. It can also be used in the place of a variable.
Q #17) How is Exception Handling done in Python?
Answer: There are 3 main keywords i.e. try, except and finally which are used to catch exceptions and handle the recovering mechanism accordingly. Try is the block of a code which is monitored for errors. Except block gets executed when an error occurs.
The beauty of the final block is to execute the code after trying for error. This block gets executed irrespective of whether an error occurred or not. Finally block is used to do the required cleanup activities of objects/variables.
Q #18) What is the starting point of Python code execution?
Answer: As Python is an interpreter, it starts reading the code from the source file and starts executing them.
However, if you want to start from the main function, you should have the following special variable set in your source file as:
Q #19) Name some of the important modules that are available in Python.
Answer: Networking, Mathematics, Cryptographic services, Internet data handling, and Multi-threading modules are prominent modules. Apart from these, there are several other modules that are available in the Python developer community.
Q #20) Which module(s) of Python can be used to measure the performance of your application code?
Answer: Time module can be used to calculate the time at different stages of your application and use the Logging module to log data to a file system in any preferred format.
Q #21) How do you launch sub-processes within the main process of a Python application?
Answer: Python has a built-in module called sub-process. You can import this module and either use run() or Popen() function calls to launch a sub-process and get the control of its return code.
Q #22) As Python is more suitable for the server-side application, it is very important to have threading implemented in your server code. How can you achieve that in Python?
Answer: We should use the threading module to implement, control and destroy threads for parallel execution of the server code. Locks and Semaphores are available as synchronization objects to manage data between different threads.
Q #23) Do we need to call the explicit methods to destroy the memory allocated in Python?
Answer: Garbage collection is an in-built feature in Python which takes care of allocating and de-allocating memory. This is very similar to the feature in Java.
Hence, there are very fewer chances of memory leaks in your application code.
Q #24) Does the same Python code work on multiple platforms without any changes?
Answer: Yes. As long as you have the Python environment on your target platform (Linux, Windows, Mac), you can run the same code.
Q #25) How can you create a GUI based application in Python for client-side functionality?
Answer: Python along with standard library Tkinter can be used to create GUI based applications. Tkinter library supports various widgets which can create and handle events which are widget specific.
Q #26) What are the different environment variables identified by Python?
PYTHONPATH: This environment variable helps the interpreter as to where to locate the module files imported in the program.
PYTHONSTARTUP: This environment variable contains the path of the Initialization file containing source code.
PYTHONCASEOK: This variable is used to find the first case-insensitive match in the import statement
Q #27) What is Python Tuples and how is it different from Lists?
Answer: Tuples is basically a sequence of elements which are separated by commas and are enclosed in a parenthesis.
Lists whereas is a sequence of elements which are separated by commas and are enclosed in brackets. Also, Tuples cannot be updated whereas, in lists, elements can be updated along with their sizes.
Q #28) What does ‘#’ symbol do in Python?
Answer: ‘#’ is used to comment out everything that comes after; on the line.
print (“I am beginner in Python”)
#print (“I am beginner in Python”)
I am beginner in Python
Q #29) What does stringVar.strip() does?
Answer: This is one of the string methods which removes leading/trailing white space.
Q #30) What should be the output of following code:
print(‘%. 6s’ % a)
Answer: Output should be: python
Q #31) Write a command to read:
a. ‘10’ characters from a file
b. Read entire file
c. Write output after executing both commands together.
Where file name is “softwaretestinghelp.txt”.
Python is a powerful high-level, object-oriented programming language created by Guido van Rossum.
It has simple easy-to-use syntax, making it the perfect language for someone trying to learn computer programming for the first time.
Answer: f = open (“softwaretestinghelp.txt “, “r”)
print (f. read (10))
print (f. read ())
is a powerful high-level, object-oriented programming language created by Guido van Rossum.
It has simple easy-to-use syntax, making it the perfect language for someone trying to learn computer programming for the first time.
Q #32) What are membership operators in Python? Write an example to explain both.
Answer: There are 2 types of membership operators in Python:
in: If the value is found in a sequence, then the result becomes true else false
not in: If the value is not found in a sequence, then the result becomes true else false
a=15 b=30 list= [3,6,15,20,30]; if (a in list) print “a is available in given list” else print “a is not available in given list” if (b not in list) print “b is not available in given list” else print “b is available in given list”
a is available in given list
b is available is list
Q #33) Write a code to display the current time.
Answer: currenttime= time.localtime(time.time())
print (“Current time is”, currenttime)
Q #34) What is the output of print str[4: ] if str = ‘ Python Language’?
Output: on Language
Q #35) Write the command to get all keys from the dictionary.
Answer: print dict.keys()
Q #36) Write a command to convert a string into an int in python.
Answer: int(x [,base])
Q #37) What are a help () and dir() in python?
Answer: help () is a built-in function that can be used to return the Python documentation of a particular object, method, attributes, etc.
dir () displays a list of attributes for the objects which are passed as an argument. If dir() is without the argument then it returns a list of names in current local space.
Q #38) What does term ‘Monkey Patching’ refers to in Python?
Answer: Monkey Patching refers to the modification of a module at run-time.
Q #39) What do you mean by ‘suites’ in Python?
Answer: The group of individual statements, thereby making a logical block of code is called suites
Example:If expression Suite Else Suite
Q #40) What is range () in Python? Give an example to explain it.
Answer: It is a function to iterate over a sequence of numbers.
for var in list(range (10))
Q #41) What is the difference between abs () and fabs ()?
Answer: abs () is a built-in function which works with integer, float and complex numbers also.
fabs () is defined in math module which doesn’t work with complex numbers.
Q #42) Write the output for the following code:
Code: str = “Python is a programming language”
str = “This is Interview Question17”
Q #43) What is a from import statement and write the syntax for it?
Answer: From statement allows specific attributes to be imported from a module in a current namespace.
Syntax: from modname import name1[, name2[, … nameN]]
Q #44) What is the difference between locals() and globals ()?
Answer: locals() is accessed within the function and it returns all names that can be accessed locally from that function.
globals() returns all names that can be accessed globally from that function.
Q #45) What is the use of Assertions in Python?
Answer: Assert statement is used to evaluate the expression attached. If the expression is false, then python raised AssertionError Exception.
Q #46) What is the difference between ‘match’ and ‘search’ in Python?
Answer: Match checks for the match at the beginning of the string whereas search checks for the match anywhere in the string
Q #47) What is the difference between shallow copy and deep copy?
Answer: Shallow copy is used when a new instance type gets created and it keeps values that are copied whereas deep copy stores values that are already copied.
A shallow copy has faster program execution whereas deep coy makes it slow.
Q #48) What statement is used in Python if the statement is required syntactically but no action is required for the program?
Answer: Pass statement
Q #49) What does PEP8 refer to?
Answer: PEP8 is a coding convention which is a set of recommendations of how to make the code more readable.
Q #50) What are *args and *kwargs?
Answer: They are used to pass a variable number of arguments to a function. *args is used to pass non-keyworded, variable length argument list whereas *kwargs is used to pass keyworded, variable length argument list.
Hope this article helped you to understand the nature of popular interview questions related to python.
Kindly note that apart from theoretical knowledge, you must possess very strong logical and analytical skills to write some Python programs during the interview session.
Wish you all the best!!
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