Python interview questions and answers -

1. What are some distinct features of Python?

Some distinct features of Python are:

a) Structured and functional programming is supported.

b) It can be compiled to byte code to create larger applications.

c) Supports high-level dynamic data types.

d) Supports checking of dynamic data types.

e) It could be used effectively along with Java, COBRA, C, C++, ActiveX, and COM.

2. What is the Pythoncaseok environment variable?

The Pythoncaseok environment variable is applied in Windows with the purpose of directing Python to find the first case insensitive match in an import statement.

3. Briefly explain some characteristics of Python.

Marks and devious Semikoli but the Little Blind Text didn’t listen. She packed her seven versalia, put her initial into the belt and made herself on the way.

4. What is Pythonpath?

A Pythonpath tells the Python interpreter to locate the module files that can be imported into the program. It includes the Python source library directory and source code directory. You can preset Pythonpath as a Python installer.

5. Why do we use the Pythonstartup environment variable?

The variable consists of the path in which the initialization file carrying the Python source code can be executed. This is needed to start the interpreter.

6. What is the major difference between tuples and lists in Python?

There are several major differences between tuples and lists in Python, which include the following:

Tuples	List
Tuples are similar to a list, but they are enclosed within parentheses, unlike the list	The list is used to create a sequence
The element and size can be changed	The element and size cannot be changed
They cannot be updated	They can be updated
They act as read-only lists	They act as a changeable list
Tuples use parentheses	Lists use square brackets
Example: tup = (1, "a", "string", 1+2)	Example: L = [1, "a" , "string" , 1+2]

7. What does the method object() do?

The method returns a featureless object that is base for all classes. This method does not take any parameters.

8. What are positive and negative indices?

Positive indices are applied when the search begins from left to right. In negative indices, the search begins from right to left. For example, in the array list of size n the positive index, the first index is 0, then comes 1, and until the last index is n-1. However, in the negative index, the first index is -n, then -(n-1) until the last index -1.

9. What is the permitted length of the identifier?

The length of the identifier in Python can be of any length. The longest identifier will be from PEP – 8 and PEP – 20.

10. What is namespace in Python?

A namespace is a naming system used to make sure names are unique to avoid naming conflicts

11. What is pep 8?

Python Enhancement Proposal or pep 8 is a set of rules that specify how to format Python code for maximum readability.

12. Define self in Python.

Self is an instance of a class or an object in Python. It is included as the first parameter. It helps differentiate between the methods and attributes of a class with local variables.

13. Is indentation necessary in Python?

Indentation is required in Python if not done properly the code is not executed properly and might throw errors. Indentation is usually done using four space characters.

14. Define a function in Python.

A block of code that is executed when it is called is defined as a function. The keyword def is used to define a Python function.

15. Do runtime errors exist in Python? Give an example.

Yes, runtime errors exist in Python. For example, if you are duck typing and things look like a duck, then it is considered a duck even if that is just a flag or stamp. The code, in this case, would be a run-time error. For example, Print “Hackr io” would result in the runtime error of the missing parenthesis that is required by print ( ).

16. What are the limitations of Python?

There are limitations to Python, which include the following:

a) It has design restrictions.

b) It is slower when compared with C and C++ or Java.

c) It is inefficient for mobile computing.

d) It consists of an underdeveloped database access layer.

17. What is the Pass statement?

A Pass statement in Python is used when we cannot decide what to do in our code, but we must type something to make it syntactically correct.

18. Can we use a break and continue together in Python? How?

Break and continue can be used together in Python. The break will stop the current loop from execution, while the jump will take it to another loop.

19. Why do we need a continue?

A continue helps control the Python loop by making jumps to the next iteration of the loop without exhausting it.

20. Why do we need a break?

Break helps control the Python loop by breaking the current loop from execution and transferring the control to the next block.

21. In how many ways can we apply reverse strings?

There are five ways in which the reverse string can be applied:

a) Loops

b) Recursions

c) Stacks

d) Extended slice syntax

e) Reversed function

22. Does Python support an intrinsic do-while loop?

No, Python does not support an intrinsic do-while loop.

23. Define slicing in Python.

Slicing refers to the mechanism to select the range of items from sequence types like lists, tuples, strings.

24. What are the different stages of the life cycle of a thread?

The different stages of the life cycle of a thread are:

Stage 1:

Creating a class where we can override the run method of the Thread class.

Stage 2:

We make a call to start() on the new thread. The thread is taken forward for scheduling purposes.

Stage 3:

Execution takes place wherein the thread starts execution, and it reaches the running state.

Stage 4:

Thread waits until the calls to methods including join() and sleep() take place.

Stage 5:

After the waiting or execution of the thread, the waiting thread is sent for scheduling.

Stage 6:

Running thread is done by executing the terminates and reaches the dead state.

25. What is docstring?

Docstring is a Python documentation string, it is a way of documenting Python functions, classes, and modules.

26. What are relational operators, assignment operators, and membership operators?

a) The purpose of relational operators is to compare values.

b) The assignment operators in Python can help in combining all the arithmetic operators with the assignment symbol.

c) Membership operators in Python with the purpose to validate the membership of a value in a sequence.

27. Differentiate between list and tuple.

Tuple is not mutable it can be hashed eg. key for dictionaries. On the other hand, lists are mutable.

28. What are Python decorators?

A specific change made in Python syntax to alter the functions easily are termed as Python decorators.

29. How are identity operators different from membership operators?

Unlike membership operators, the identity operators compare the values to find out if they have the same value or not.

30. Draw a comparison between the range and xrange in Python.

In terms of functionality, both range and xrange are identical. Both allow for generating a list of integers. The main difference between the two is that while range returns a Python list object, xrange returns an xrange object.

Xrange is not able to generate a static list at runtime the way range does. On the contrary, it creates values along with the requirements via a special technique called yielding. It is used with a type of object known as generators.

If you have an enormous range for which you need to generate a list, then xrange is the function to opt for. This is especially relevant for scenarios dealing with a memory-sensitive system, such as a smartphone.

The range is a memory hog. Using it requires much more memory, especially if the requirement is gigantic. Hence, in creating an array of integers to suit the needs, it can result in a memory error and ultimately lead to a crash.

31. Describe multithreading in Python.

Using Multithreading to speed up the code is not the go-to option, even though Python comes with a multi-threading package.

The package has the GIL or Global Interpreter Lock, which is a construct. It ensures that only one of the threads executes at any given time. A thread acquires the GIL and then performs work before passing it to the next thread.

This happens so fast that to a user it seems that threads are executing in parallel. Obviously, this is not the case as they are just taking turns while using the same CPU core. GIL passing adds to the overall overhead to the execution.

As such, if you intend to use the threading package for speeding up the execution, using the package is not recommended.

32. How do you capitalize the first letter of string?

The capitalize() method capitalizes the first letter of the string, and if the letter is already capital it returns the original string

33. Explain how to acquire the Google cache age of any URL or webpage using Python.

In order to get the Google cache age of any URL or webpage using Python, the following URL format is used:

http://webcache.googleusercontent.com/search?q=cache:URLGOESHERE

Simply replace URLGOESHERE with the web address of the website or webpage whose cache you need to retrieve and see in Python.

34. Can we reverse a list in Python?

Yes, we can reserve a list in Python using the reverse() method. The code is as follows:

def reverse(s):

str = ""

for i in s:

str = i + str

return str

35. How is a file deleted in Python?

The file can be deleted by either of these commands:

os.remove(filename)
os.unlink(filename)

36. Explain how to acquire the Google cache age of any URL or webpage using Python.

In order to get the Google cache age of any URL or webpage using Python, the following URL format is used

Simply replace URLGOESHERE with the web address of the website or webpage whose cache you need to retrieve and see in Python.

Python Advanced Interview Questions

37.What is the output of the following code?

A0 = dict(zip(('a','b','c','d','e'),(1,2,3,4,5)))

A1 = range(10)

A2 = sorted([i for i in A1 if i in A0])

A3 = [i for i in A1 if i in A3]

A4 = [i for i in A1 if i in A3]

A5 =

A6 = [[i, i*i] for i in A1]

print(A0,A1,A2,A3,A4,A5,A6)

ans

A0 = {'a': 1, 'c': 3, 'b': 2, 'e': 5, 'd': 4} # the order may vary
A1 = range(0, 10)
A2 = []
A3 = [1, 2, 3, 4, 5]
A4 = [1, 2, 3, 4, 5]
A5 =
A6 = [[0, 0], [1, 1], [2, 4], [3, 9], [4, 16], [5, 25], [6, 36], [7, 49], [8, 64], [9, 81]]

38. Suppose you need to collect and print data from IMDb top 250 Movies page. Write a program in Python for doing so. (NOTE: You can limit the displayed information for 3 fields; namely movie name, release year, and rating.)

from bs4 import Beautifulsoup

import requests

import sys

url = 'http://www.imdp.com/chart/top'

response = requests.get(url)

soup = Beautifulsoup(response.text)

tr = soup.findchildren("tr")

tr = iter(tr)

for movie in tr:

title = movie.find('td' , {'class': 'titlecolum'}.find('a').contents[0]

year = movie.find('td', {'class: 'titlecolumn'}).find('span',{'class':'secondaryinfo'}).contents[0]

rating = movie.find('td',{'class': 'ratingcolumn imdbrating'} ).find('strong').contents[0]

row = title + ' - ' + ' ' + rating

print(row)

39. Python supports negative indexes. What are they and why are they used?

The sequences in Python are indexed. It consists of positive and negative numbers. Positive numbers use 0 as the first index, 1 as the second index, and so on. Hence, any index for a positive number n is n-1.

Unlike positive numbers, index numbering for the negative numbers starts from -1 and it represents the last index in the sequence. Likewise, -2 represents the penultimate index. These are known as negative indexes. Negative indexes are used for:

a.) Removing any new-line spaces from the string, thus allowing the string to except the last character, represented as S[:-1]

b.) Showing the index to representing the string in the correct order

40. Explain dictionaries with an example.

A dictionary in the Python programming language is an unordered collection of data values such as a map. Dictionary holds the key:value pair. This helps define a one-to-one relationship between keys and values. Indexed by keys, a typical dictionary contains a pair of keys and corresponding values.

Let us take an example with three keys, namely website, language, and offering. Their corresponding values are hackr.io, Python, and Tutorials. The code for would be

41. What is the output of the following code?

Far far away, behind the word mountains, far from the countries Vokalia and Consonantia, there live the blind texts. Separated they live in Bookmarksgrove right at the coast

try: if '1' !=1;

raise "someerror"

else: print("someError has not occured")

expect "someError":pr

int ("someError has occured")

42. Explain the process of compilation and linking.

In order to compile new extensions without any error, compiling and linking is used in Python. Linking initiates only and only when the compilation is complete.

In the case of dynamic loading, the process of compilation and linking depends on the style that is provided with the concerned system. In order to provide dynamic loading of the configuration setup files and rebuilding the interpreter, the Python interpreter is used.

43. What is Flask and what are the benefits of using it?

Flask is a web microframework for Python with Jinja2 and Werkzeug as its dependencies. As such, it has some notable advantages:

a) Flask has little to no dependencies on external libraries.

b) Because there is a little external dependency to update and fewer security bugs, the web microframework is lightweight.

c) It has an inbuilt development server and a fast debugger.

44. What is monkey patching in Python?

The dynamic modifications made to a class or module at runtime are termed as monkey patching in Python. Consider the following code snippet:

class myclass:

def f(self):

print "f()"

we can monkey-patch the program something like this

import m

def monkey_f(self):

print "monkey_f()"

m.Myclass.f = monkey_f

obj = m.Myclass()

obj.f()

45. What is the map() function used for?

The map() function applies a given function to each item of an iterable. It then returns a list of the results. The value returned from the map() function can then be passed on to functions to the likes of the list() and set().

Typically, the given function is the first argument and the iterable is available as the second argument to a map() function. Several tables are given if the function takes in more than one argument.

46. Whenever Python exits, not all the memory is deallocated. Why is it so?

Upon exiting, Python’s built-in effective cleanup mechanism comes into play and tries to deallocate or destroy every other object. However, Python modules that have circular references to other objects, or the objects that are referenced from the global namespaces, aren’t always deallocated or destroyed.

This is because it is not possible to deallocate those portions of the memory that are reserved by the C library.

47. How is memory managed in Python?

Python private heap space takes place of memory management in Python. It contains all Python objects and data structures. The interpreter is responsible to take care of this private heap and the programmer does not have access to it. The Python memory manager is responsible for the allocation of Python heap space for Python objects. The programmer may access some tools for the code with the help of the core API. Python also provides an inbuilt garbage collector, which recycles all the unused memory and frees the memory and makes it available to heap space.

48. How are arguments passed in Python? By value or by reference?

All of the Python is an object and all variables hold references to the object. The reference values are according to the functions; as a result, the value of the reference cannot be changed.

49. Explain the Dogpile effect.

The dogpile effect is when the cache expires and websites are hit by multiple requests made by the client at the same time. Using a semaphore lock prevents the Dogpile effect. In this system when a value expires, the first process acquires the lock and starts generating a new value.

50. What is the split function used for?

The split function breaks the string into shorter strings using the defined separator. It returns the list of all the words present in the string.

Top 50 Python Interview Questions and Answers