Python Interview Questions for Experienced – 5 Yrs

1. How is memory management done in Python?

In Python memory management is done using private heap space. The private heap is the storage area for all the data structures and objects. The interpreter has access to the private heap and the programmer cannot access this private heap.

The storage allocation for the data structures and objects in Python is done by the memory manager. The access for some tools is provided by core API for programmers to code. The built-in garbage collector in Python is used to recycle all the unused memory so that it can be available for heap storage.

2. State the difference between Java vs Python

The major difference between Java and Python are as follows:

In Java, we need to write a long code to print something.
In Java we need to put a semicolon at the end of the statement and also code must be placed in curly braces.
In Java, we need to declare the type for each variable
Java is not easy to use because of its larger coding
Java Database Connectivity (JDBC) is more popular and used most commonly.
PythonIn Python coding is simple and smaller when compared to Java
Whereas, in Python indentation is mandatory as it improves the readability of the code.
In this case, codes are dynamically typed and this is also known as duck typing
In Python, it is very easy to code and perform very easily.
In Python database access layers are weaker when compared to Java.

3. How can Python be an interpreted language?

As in Python the code which we write is not machine-level code before runtime so, this is the reason why Python is called an interpreted language.

4. What happens when a function doesn’t have a return statement? Is this valid?

Yes, this is valid. The function will then return a None object. The end of a function is defined by the block of code that is executed (i.e., the indenting) not by any explicit keyword.

5. How can we make a Python script executable on Unix?

In order to make a Python script executable on Unix, we need to perform two things. They are: Script file mode must be executable and The first line should always begin with #.

6. What is the Python String format and Python String replace?

Python String Format:The String format() method in Python is mainly used to format the given string into an accurate output or result.

Syntax for String format() method:

template.format(p0, p1, …, k0=v0, k1=v1, …)

Python String Replace: This method is mainly used to return a copy of the string in which all occurrences of the substring is replaced by another substring.

7. Differentiate between SciPy and NumPy?

NumPyNumerical Python is called NumPy. It is used for performing general and efficient computations on numerical data which is saved in arrays. For example indexing, reshaping, sorting, and so on.

Scipy (Scientific Python) is mainly used to perform various operations like differentiation, integration and many more. For performing algebraic computations this module contain some of the fully fledged operations.

8. How do Python arrays and lists differ from each other?

Array is defined as a linear structure that is used to store only homogeneous data. Since an array stores only similar type of data, it occupies less amount of memory when compared to a list. Length of the array is fixed at the time of designing and no more elements can be added in the middle.

List are used to store arbitrary and heterogenous data. List stores different types of data so it requires huge amount of memory. Length of the list is no fixed, and adding items in the middle is possible in lists.

9. List the features of Django?

Excellent documentation.
Python web framework.
SEO optimised.
High scalability.
Versatile in nature.
Offers high security.
Thoroughly tested.
Provides rapid Development.

10. Which level framework does Django belong to?

Django is a high-level Python web framework which was developed for realistic design, clean, rapid development.

11. What are the advantages of Django?

The Django framework is very simple to learn as a multifaceted framework. When it comes to security, Django is the best framework. Scalability is an added advantage of Django.

12. Why should we use the Django framework?

Django is used widely because of its simplicity and rapid development, which implies it can complete more than one iteration at a time without beginning the full schedule from scratch. DRY philosophy — Do not Replicate Yourself — Developers can reuse surviving code and also focus on the individual one.

13. List the common security issues that can be avoided by using Django?

Few common security issues that can be avoided by using Django are:

Clickjacking.
Cross-site scripting.
SQL injection.

14. List a few of the famous companies that are using Django?

Few well-known companies that are using the Django framework are:

Instagram.
Spotify.
Mozilla.
Dropbox.
NASA.

15. What can we do with the Django framework?

Django was first created to power a web application as a newspaper publisher, the Lawrence Journal-World. It is very good in handling projects with large volumes from the text files, media, including extremely high traffic and web publication.

16. List steps for setting up static files in Django?

There are only three main steps for setting up Django static files:

Firstly set STATIC_ROOT in settings.py,
Run manage.py collect static,
Setting up a static file entry pythonAnywhere tab.

17. Is Django stable?

Yes, Django is used by many famous companies because it is quite stable.

18. Differentiate Django reusability code with other frameworks?

Django web framework is operated and also maintained by an autonomous and non-profit organization designated as Django Software Foundation (DSF). The initial foundation goal is to promote, support, and advance this Django Web framework.

19. How can we handle URLs in Django?

from django.contrib import admin from django.urls import path urlpatterns = [ path(appmajix/, appmajix.site.urls), ]

20. List the mandatory files of the Django project?

manage.py settings.py __init__.py urls.py wsgi.py

21. Explain about the Django session?

A session comprises a mechanism to store information on specific server-side at the interaction by the web application. By default, session reserves in the database and allows file-based and cache-based sessions.

22. Why do we use a cookie in Django?

A cookie is a piece of information that is stored in a client browser for a specific time. When the specific time is completed the cookie gets automatically removed from the client browser.

23. What is the use of Django-admin.py?

Django-admin.py is a command-line argument which is used for administrative tasks.

24. What is the use of manage.py?

manage.py is an automatically built file inside each Django project. It is a flat wrapper encompassing the Django-admin.py.

manage.py possesses the following usage:

Establishes your project’s package on sys.path. It fixes the DJANGO_SETTING_MODULE environment variable to point to your project’s setting.py file.

25. Why is Django loosely packed?

Django has been described as a loosely coupled framework because of the MTV architecture it’s based upon. Django’s architecture is a variant of MVC architecture and also MTV is helpful because this completely separates the server code of the client’s machine.

26. Explain how we can build or set up the database in Django?

We can make use of the edit mysite/setting.py command, it is a simple Python module consisting of levels for presenting or displaying Django settings. By default Django uses SQLite – this also makes it easy for Django users in case of any other type of installation. For example, if your database choice is different then you need to follow certain keys in the DATABASE like default items to match database connection settings. Engines: By these engines you change the database by using commands such as:

‘django.db.backends.postgresql_psycopg2’,

‘django.db.backends.sqlite3’, ‘django.db.backends.oracle’, ‘django.db.backends.mysql’

Name: This represents the name of your own database. If you are familiar with using SQLite as your database, in such a case the database is available as a file on your particular system. Moreover, the name should be a fully absolute or exact path along with the file name of the particular file. Suppose if we are not using SQlite as your database then additional settings such as password, user, the host must be added.

27. List out the inheritance styles in Django?

There are three possible inheritance styles in Django, and they are:

Proxy models: This style is mainly used for those who want to modify the Python level behavior of the model, without modifying the model’s fields.

Abstract Base Classes: This inheritance style is used only when we want to make the parent class hold the data which they don’t want to repeat it again in the child class.

Multi-table Inheritance: This inheritance style is used only when we want to subclass an existing model and there must be a database table designed for each model on its own.

28. How to save an image locally using Python in which we already know the URL address?

The following code is used to save the image locally from the URL address which we know.

import urllib.request urllib.request.urlretrieve(URL, local-filename.jpg)

29. How can we access sessions in flask?

A session will basically allow us to remember information from one request to another. In a flask, a signed cookie is used to make the user look at the session contents and modify them. Moreover, the user can change the session only when the secret key named Flask.secret_key is present.

30. What are the database connections in Python Flask, explain?

Database powered applications are supported by flask. The relational database systems need to create a schema that requires piping the schema.sql file into a SQLite3 command. So, in this case you need to install SQLite3 command on your system to initiate and create the database in the flask.We can request a database using flask in three ways, and they are:

before_request(): Using this we can request the database before only without passing arguments.

after_request(): This method is called after requesting the database and also sending the response to the client.

teardown_request(): This method is called in the cases where the responses are not guaranteed and the exception is raised. They have no access to modify the request.

31. Explain the procedure to minimize or lower the outages of Memcached server in your Python development?

The following are the steps used to minimize the outages of the Memcached server in your Python development, and they are.

When a single instance fails, this will impact the larger load of the database server. The client makes the request when the data is reloaded. In order to avoid this, the code that you have written must be used to lower cache stampedes then it will be used to leave a minimal impact.

The other way is to bring out the instance of the memcached on a new machine by using the IP address of the lost machine. Another important option is to lower the server outages.

This code provides you the liberty to modify the memcached server list with minimal work Another way is by setting timeout value that will be one of the options for memcached clients to implement the memcached server outage. When the performance of the server goes down, the client keeps on sending a request until the timeout limit is reached.

Class Student: def __init__(self, name): self.name = name S1=Student(XYZ) print(S1.name)

32. What is the Dogpile effect?

This is defined as an occurrence of an event when the cache expires and also when the websites are hit with more requests by the client at a time. This dogpile effect can be averted by the use of a semaphore lock. If in the particular system the value expires then, first of all, the particular process receives the lock and begin generating new value.

33. Is multiple inheritance supported in Python?

Multiple inheritance is supported in python. It is a process that provides flexibility to inherit multiple base classes in a child class. Example of multiple inheritance in Python is as follows:

class Calculus: def Sum(self,a,b): return a+b; class Calculus1: def Mul(self,a,b): return a*b; class Derived(Calculus,Calculus1): def Div(self,a,b): return a/b; d = Derived() print(d.Sum(10,30)) print(d.Mul(10,30)) print(d.Div(10,30)) Output: 40 300 0.3333

34. Why is Flask considered a microframework?

Flask is a lightweight web framework for Python that allows developers to build web applications quickly. It is considered a microframework because it doesn’t come with built-in tools like form validation, database abstraction, or authentication. Instead,

Flask provides the basic necessities (like routing and request handling), and developers can add extensions as needed. This gives flexibility but keeps the core framework simple and easy to learn.

35. How does Flask handle routing?

Flask uses decorators to associate URLs with Python functions. The @app.route() decorator is used to define the route for an endpoint. When a user accesses a particular URL, Flask maps that URL to the corresponding view function, which handles the request.

from flask import Flask app = Flask(__name__) @app.route(‘/’) def home(): return “Welcome to the Credo Systemz homepage!”

36. What is the purpose of Flask’s render_template function?

render_template is used to render HTML templates with dynamic content. Flask uses Jinja2 as its template engine, allowing developers to inject data into HTML files and control the structure dynamically.

from flask import Flask, render_template app = Flask(__name__) @app.route(‘/’) def home(): return render_template(‘home.html’, name=”xyz”)

Here, Flask will render the home.html file, passing the variable name to the template, where it can be used like {{ name }}.

37. How does Flask handle HTTP methods (GET, POST, etc.)?

Flask allows developers to specify which HTTP methods a route can accept by passing a methods argument to the @app.route() decorator. By default, Flask routes handle only GET requests, but you can specify other methods like POST, PUT, and DELETE.

from flask import Flask, request

app = Flask(__name__) @app.route(‘/submit’, methods=[‘GET’, ‘POST’]) def submit(): if request.method == ‘POST’: data = request.form[‘data’] return f”Data received: {data}” return “Submit data through POST.”

This example listens for both GET and POST. For POST requests, it captures form data from the request object.

38. How do you handle error pages in Flask?

Flask allows you to customize error pages by using the @app.errorhandler() decorator. This lets you create custom responses for common HTTP errors, such as 404 Not Found or 500 Internal Server Error.

39. What are dunder methods in Python, and why are they used?

Dunder methods (short for “double underscore”) are special methods that allow us to define the behavior of objects for built-in operations. They are also called magic methods.

For example:

__init__ is used for object initialization,

__str__ for defining how an object should be represented as a string, __add__ to define the behavior of the + operator for custom objects.

40. Explain the concept of metaclasses in Python.

Metaclasses in Python define the behavior of a class. In Python, everything is an object, including classes. A metaclass is the class of a class. It controls how classes are created and can be used to modify class creation at runtime.

class Meta(type): def __new__(cls, name, bases, dct): print(f’Creating class {name}’) return super().__new__(cls, name, bases, dct) class MyClass(metaclass=Meta): pass

When MyClass is defined, the Meta class’s __new__ method will be called.

41. What is method resolution order (MRO)?

Method Resolution Order (MRO) determines the order in which base classes are searched when calling a method. Python uses the C3 linearization algorithm to compute the MRO. The MRO can be viewed using the __mro__ attribute or the mro() method.

42. What is the difference between @classmethod, @staticmethod, and instance methods in Python?

Instance methods: Take self as the first parameter and can modify object instance state.

Class methods: Take cls as the first parameter and are bound to the class, not instances. They can modify class state.

@classmethod def class_method(cls): pass

Static methods: Do not take self or cls as a parameter and cannot modify class or instance state. They are just functions defined inside a class.

@staticmethod def static_method(): pass

43. How does Python’s super() work in multiple inheritance?

super() allows us to call a method from the parent class in a subclass. In multiple inheritance, super() follows the MRO (Method Resolution Order) to ensure that the method of the next class in the hierarchy is called.

class A: def show(self): print(“A”) class B(A): def show(self): super().show() print(“B”) class C(A): def show(self): super().show() print(“C”) class D(B, C): def show(self): super().show() print(“D”) Calling D().show() will print A -> C -> B -> D, following the MRO.

44. Can you explain the slots mechanism?

The __slots__ mechanism is used to restrict the creation of instance attributes to a predefined list, which can save memory by not using a dictionary to store attributes for each instance. This can improve performance when many instances of a class are created.

45. What is the difference between deep copy and shallow copy in Python?

Shallow copy: Creates a new object but inserts references into it to the original objects (one level deep). This means changes to nested objects in the original will affect the copied object.

Deep copy: Creates a new object and recursively copies all objects found. Changes to the original objects do not affect the deep copy.

46. How do Python descriptors work?

A descriptor in Python is an object that defines how an attribute is accessed. A descriptor class implements any of the __get__(), __set__(), or __delete__() methods. Descriptors are used to manage attribute access in custom ways.

47. Explain monkey patching in Python. Is it a good practice?

Monkey patching refers to dynamically modifying or extending a class or module at runtime. While it can be useful in certain situations like testing or fixing bugs in third-party libraries, it is generally considered bad practice because it can lead to unpredictable behavior and make code harder to maintain.

48. What is the difference between composition and inheritance?

Inheritance: Represents an “is-a” relationship. Use it when one class is a subtype of another.

Example: A Dog class inherits from an Animal class.

Composition: Represents a “has-a” relationship. Use it when you want to compose objects using other objects.

Example: A Car class may have an Engine object rather than inheriting from Engine.

49. How is encapsulation implemented in Python?

Encapsulation in Python is implemented through class attributes and methods, and access to these can be controlled using access modifiers. Although Python does not have strict access control like some other languages (e.g., private, protected, and public keywords), it provides conventions:

Public Attributes: These are accessible from anywhere (default behavior).
Protected Attributes: By convention, attributes prefixed with a single underscore (_attribute) should not be accessed outside the class or its subclasses. However, this is only a weak form of encapsulation.
Private Attributes: To make an attribute more restricted, a double underscore (__attribute) is used. This triggers name mangling, making it harder (but not impossible) to access the attribute outside the class. The attribute is internally renamed to _ClassName__attribute.

50. How would you achieve strict encapsulation in Python to prevent any external access to sensitive class attributes?

While Python’s encapsulation relies on conventions, you can combine advanced techniques to enforce stricter encapsulation:

Private Attributes with Name Mangling: You can declare private attributes using a double underscore to make them difficult to access directly.
Properties with Getters/Setters: Use the @property decorator to manage access to these private attributes, allowing controlled read and write access while hiding the underlying implementation.
Preventing Dynamic Attribute Addition: By using __slots__, you can prevent users from dynamically adding new attributes, ensuring the class remains more secure and memory efficient.

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Python Interview Questions for Experienced – 5 Yrs