100+ Python Developer Interview Questions and Answers

The logic of the program is to reverse a given string word by word without using any built-in function.

• Split the string into an array of words using whitespace as the delimiter.

• Iterate through the array of words in reverse order.

• Append each word to a new string, separated by a space.

Answers to interview questions for a Python developer.

• 1. Tuples are immutable while lists are mutable.

• 2. Decorators are functions that modify the behavior of other functions.

• 3. 'to' object is not a standard term in Python, so it's unclear.

• 4. Pass does nothing, break exits the loop, and continue skips to the next iteration.

• 5. Need the given program to identify the error.

• 6. Explain your projects in detail, highlighting your role and achievements.

Variables are names given to memory locations while objects are instances of a class with attributes and methods.

• Variables are used to store values while objects are used to represent real-world entities.

• Variables can be reassigned to different values while objects have a fixed identity.

• Variables are created when they are assigned a value while objects are created using constructors.

• Variables can be of different data types while objects are instances of a specific class.

• Examp...read more

This program reverses a given string without using any built-in methods.

• Iterate through the string from the last character to the first character.

• Append each character to a new string to reverse the order.

• Return the reversed string as the output.

To check if a key exists in a dictionary without raising a KeyError.

• Use the 'in' keyword to check if the key exists in the dictionary.

• Use the 'get' method to return a default value if the key does not exist.

• Use the 'keys' method to get a list of all keys and check if the key is in the list.

Local variables are variables that are defined within a function and can only be accessed within that function. Global variables are variables that are defined outside of any function and can be accessed throughout the program.

• Local variables are created when a function is called and destroyed when the function completes.

• Global variables can be accessed and modified by any function in the program.

• Using local variables helps in encapsulation and prevents naming conflicts.

• Globa...read more

Yes, the key of a dictionary in Python can be changed. The criteria for selecting a key are immutability and uniqueness.

• The key of a dictionary can be any immutable data type such as strings, numbers, or tuples.

• The key must be unique within the dictionary, as duplicate keys are not allowed.

• Changing the value of a key is allowed, but changing the key itself requires creating a new key-value pair.

• Keys that are mutable, such as lists, cannot be used as dictionary keys.

To get the value for a key from a dictionary in Python, use the square bracket notation or the get() method.

• Use square brackets and the key name to access the value directly: dictionary[key]

• Alternatively, use the get() method to retrieve the value: dictionary.get(key)

• If the key is not present in the dictionary, using square brackets will raise a KeyError, while get() will return None or a default value if specified

Arrays are homogeneous data structures while lists are heterogeneous data structures in Python.

• Arrays are fixed in size while lists are dynamic.

• Arrays can only contain elements of the same data type while lists can contain elements of different data types.

• Arrays are faster and more memory-efficient for numerical operations.

• Lists have more built-in functions and are more versatile for general-purpose programming.

• Example of array: import array as arr; a = arr.array('i', [1, 2, ...read more

Yes, I have worked on various python projects including web development, data analysis and automation.

• Developed a web application using Django framework

• Automated data extraction and analysis using pandas library

• Created a chatbot using Python and Dialogflow API

• Implemented machine learning algorithms for predictive analysis

• Integrated Python scripts with other technologies like AWS and Docker

A decorator is a design pattern in Python that allows modifying the behavior of a function or class without changing its source code.

• Decorators are functions that take another function as an argument and return a new function.

• They are used to add functionality to an existing function or class.

• They can be used to modify the behavior of a function, such as adding logging or timing functionality.

• They can also be used to enforce security or access control.

• A decorator is denoted b...read more

Agree, taking time to learn the new domain is crucial for success.

• Learning the new domain will help us understand the business requirements better.

• It will also help us identify potential challenges and opportunities.

• We can leverage our existing skills and knowledge to build better solutions.

• Taking time to learn the new domain will also help us build credibility with stakeholders.

• We can use this time to network and build relationships with experts in the new domain.

A brief explanation of linked list, array, multidimensional array, nested for loop, and polymorphism.

• Linked list is a data structure where each element points to the next one.

• Array is a collection of elements of the same data type stored in contiguous memory locations.

• Multidimensional array is an array with more than one dimension.

• Nested for loop is a loop inside another loop.

• Polymorphism is the ability of an object to take on many forms.

A class is a blueprint for creating objects that have properties and methods. Functions are written inside a class to define its behavior.

• A class is a user-defined data type that encapsulates data and functions that operate on that data.

• Functions written inside a class are called methods and are used to define the behavior of the class.

• The role of a class is to provide a template for creating objects that share common properties and behavior.

• Classes allow for code reusability...read more

Lists are mutable while tuples are immutable in Python.

• Lists use square brackets [] while tuples use parentheses ().

• Elements in a list can be added, removed, or modified while tuples cannot be modified.

• Lists are used for collections of homogeneous items while tuples are used for heterogeneous items.

• Lists are generally used for large collections of data while tuples are used for smaller collections or for data that should not be changed.

• Lists are slower than tuples in terms of...read more

Discussing approaches to solve a DSA problem in a Zoom call.

• Understand the problem statement and constraints.

• Choose an appropriate data structure and algorithm.

• Implement the solution and test it with sample inputs.

• Optimize the solution if possible.

• Discuss the time and space complexity of the solution.

Generators in Python are functions that can be paused and resumed, allowing for efficient memory usage and lazy evaluation.

• Generators are created using the yield keyword

• They are used to create iterators

• Generators produce a sequence of values on-the-fly

• They are memory efficient as they generate values one at a time

• Generators are useful for processing large datasets or infinite sequences

Answers to common Python interview questions.

• Namespace is a container for storing variables and functions.

• Dictionary is a collection of key-value pairs.

• Type conversion is the process of converting one data type to another.

• Arrays are homogeneous while lists are heterogeneous.

• Functions are blocks of code that perform a specific task.

Data can be sent to the database using SQL queries or an ORM like Django's ORM.

• Use SQL queries to insert, update or delete data in the database.

• Use an ORM like Django's ORM to interact with the database using Python code.

• Ensure that the data being sent is properly formatted and validated to prevent errors or security issues.

Pickling is a way to serialize Python objects, while non-pickling refers to objects that cannot be pickled.

• Pickling is used to convert Python objects into a byte stream that can be stored or transmitted.

• Non-pickling objects are those that cannot be serialized using the pickle module.

• Examples of non-pickling objects include file objects, network sockets, and database connections.

• To make an object picklable, it must be able to be reduced to a string of bytes and then reconstruc...read more

Inheritance is a way to create a new class by inheriting properties and methods from an existing class.

• It allows code reusability and saves time.

• Types of inheritance are single, multiple, multilevel, and hierarchical.

• Single inheritance involves inheriting properties and methods from a single parent class.

• Multiple inheritance involves inheriting properties and methods from multiple parent classes.

• Multilevel inheritance involves inheriting properties and methods from a parent c...read more

Python uses automatic memory management through a garbage collector.

• Python uses reference counting to keep track of objects in memory.

• When an object's reference count reaches zero, it is automatically deallocated.

• Python also employs a garbage collector to handle cyclic references.

• The garbage collector identifies and collects objects that are no longer reachable.

• Memory management in Python is transparent to the developer.

Collection data types are used to store multiple values in a single variable. HTML is a markup language, CSS is used for styling web pages, object is an instance of a class, array is a collection of similar data types, thread is a sequence of instructions executed by a CPU, and multi-threading is the ability of a CPU to execute multiple threads simultaneously.

• Collection data types include lists, tuples, and dictionaries in Python.

• HTML stands for Hypertext Markup Language and ...read more

Python is a high-level, interpreted programming language known for its simplicity, readability, and versatility.

• Python is used for web development, data analysis, artificial intelligence, and more.

• Advantages of Python include its ease of use, large standard library, and community support.

• Functions in Python are used to group related code and make it reusable.

• The break statement is used to exit a loop prematurely.

• A tuple is an ordered, immutable collection of elements.

Find the next greater element for each element in the array.

• Iterate through the array from right to left.

• Use a stack to keep track of elements with no greater element found yet.

• Pop elements from the stack until a greater element is found or stack is empty.

• Store the next greater element for each element in a result array.

The question is unclear and does not make sense.

• The question is not a valid question.

• It does not relate to Python web designing or any other topic.

• It is not possible to provide a meaningful answer to this question.

To select a particular row in SQL, use the SELECT statement with the WHERE clause.

• Use the SELECT statement to retrieve data from a table.

• Specify the table name and column names in the SELECT statement.

• Use the WHERE clause to filter the rows based on a condition.

• Specify the condition in the WHERE clause using comparison operators.

• Example: SELECT * FROM table_name WHERE column_name = 'value';

Creating a class in Python involves defining attributes and methods. Inheritance allows a class to inherit attributes and methods from a parent class.

• To create a class, use the 'class' keyword followed by the class name and a colon

• Define attributes using the '__init__' method

• Define methods within the class using the 'def' keyword

• Inheritance is achieved by defining a child class that inherits from a parent class using the 'class ChildClass(ParentClass):' syntax

• The child class ...read more

Find second highest number from list without using inbuilt functions

• Sort the list in descending order

• Return the second element of the sorted list

Python has several built-in data types including numeric, sequence, mapping, and boolean types.

• Numeric types include integers, floats, and complex numbers

• Sequence types include lists, tuples, and strings

• Mapping types include dictionaries

• Boolean type includes True and False values

Yes, init method is a special method in Python classes used to initialize objects.

• The init method is called automatically when an object is created from a class.

• It is used to set initial values for object attributes.

• The init method always takes the 'self' parameter as the first argument.

• Example: def __init__(self, name, age): self.name = name; self.age = age

• The init method can also be used to perform any other setup or initialization tasks.

Data types are categories of data items that determine the operations that can be performed on them.

• Numeric types: int, float, complex

• Sequence types: list, tuple, range

• Text type: str

• Mapping type: dict

• Set types: set, frozenset

• Boolean type: bool

• Binary types: bytes, bytearray, memoryview

Python is a high-level programming language known for its simplicity and readability.

• Python is an interpreted language, which means it does not need to be compiled before running.

• It has a large standard library that provides many useful modules and functions.

• Python supports multiple programming paradigms, including procedural, object-oriented, and functional programming.

• It is widely used in web development, data analysis, artificial intelligence, and scientific computing.

• Pyth...read more

Program to maximize money from robbing 9 houses without triggering alarm for consecutive robberies

• Create a list of money in each house

• Use dynamic programming to keep track of maximum money robbed without triggering alarm

• Consider robbing or skipping each house based on previous robberies

• Example: houses = [10, 20, 15, 25, 10, 30, 50, 5, 40]

Pickling is the process of converting a Python object into a byte stream, while unpickling is the reverse process.

• Pickling allows objects to be serialized and stored in a file or transferred over a network.

• The pickle module in Python provides functions for pickling and unpickling objects.

• Example: Pickling a list - pickle.dump([1, 2, 3], file)

• Example: Unpickling a list - pickle.load(file)

A class is a blueprint for creating objects, while an object is an instance of a class.

• A class defines the properties and behaviors that objects of that class will have.

• An object is a specific instance of a class, with its own unique data and behavior.

• Classes can be thought of as templates, while objects are the actual instances created from those templates.

• Example: Class 'Car' defines properties like 'color' and behaviors like 'drive', while an object 'myCar' is an instance ...read more

Shallow copy creates a new object with the same reference as the original, while deep copy creates a new object with a new reference.

• Shallow copy only copies the top-level object, while deep copy copies all nested objects.

• Shallow copy can be done using slicing or the copy() method, while deep copy requires the copy module.

• Modifying the original object will affect the shallow copy, but not the deep copy.

• Example: x = [[1, 2], [3, 4]]; y = x[:] # shallow copy; z = copy.deepcopy(...read more

Program to find duplicate elements in a list and add 3.

• Create an empty list to store duplicates

• Loop through the list and check if element is already in the duplicates list

• If not, add it to the duplicates list

• Add 3 to the original list

• Print the duplicates list and the updated original list

Tuple is an immutable sequence, while list is a mutable sequence in Python.

• Tuple elements cannot be modified once assigned, while list elements can be modified.

• Tuple uses parentheses () to enclose elements, while list uses square brackets [] to enclose elements.

• Tuple is generally used for heterogeneous data types, while list is used for homogeneous data types.

• Tuple is faster than list when accessing elements.

• Tuple consumes less memory than list.

Yes, we can create our custom exception in Python.

• To create a custom exception, we need to create a class that inherits from the Exception class.

• We can define our own message and error code for the custom exception.

• We can raise the custom exception using the 'raise' keyword.

• Custom exceptions can be used to handle specific errors in our code.

• Example: class MyException(Exception): pass

• Example: raise MyException('This is a custom exception')

Testers focus on finding defects while developers focus on creating software.

• Testers are responsible for testing the software and finding defects.

• Developers are responsible for creating the software and fixing defects.

• Testers use test cases and scenarios to ensure the software meets requirements.

• Developers use programming languages and tools to create software.

• Testers work closely with developers to ensure defects are fixed.

• Developers work closely with testers to understand a...read more

Python has built-in data structures like lists, tuples, sets, and dictionaries.

• Lists are mutable and ordered, used for storing multiple items.

• Tuples are immutable and ordered, used for storing multiple items.

• Sets are mutable and unordered, used for storing unique values.

• Dictionaries are mutable and unordered, used for storing key-value pairs.