200+ Python Developer Interview Questions and Answers

Django follows a Model-View-Template architecture, with models representing data, views handling logic, and templates for presentation.

• Django follows the Model-View-Template (MVT) architecture pattern.

• Models represent the data structure, Views handle the business logic, and Templates manage the presentation layer.

• Models interact with the database, Views process user requests, and Templates generate HTML output.

• Django's architecture promotes code reusability, modularity, and s...read more

Django is a high-level Python web framework that encourages rapid development and clean, pragmatic design. Flask is a lightweight WSGI web application framework.

• Django is a full-featured framework with built-in ORM, admin panel, and authentication system, while Flask is more lightweight and flexible.

• Django follows the 'batteries included' philosophy, providing many built-in features out of the box, whereas Flask is more minimalistic and allows developers to choose their own t...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.

JSON is lightweight, easy to read, and commonly used for web APIs. XML is more verbose, structured, and used for data interchange.

• JSON is lightweight and easy to read compared to XML

• XML is more verbose and structured than JSON

• JSON is commonly used for web APIs, while XML is used for data interchange

• JSON supports only text and number data types, while XML supports various data types including text, numbers, dates, and arrays

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

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

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]

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.

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.

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

The code checks if a string is a palindrome, ignoring case sensitivity.

• The string 'JaVaJ' is converted to lowercase using casefold().

• The reversed version of the string is generated but not used correctly.

• The comparison should be between the casefolded string and its reversed version.

• Correct palindrome check: 'JaVaJ' becomes 'javaj' and reversed is also 'javaj'.

Reverse each word in a sentence while keeping the word order intact.

• Split the sentence into words using the split() method.

• Reverse each word using slicing [::-1].

• Join the reversed words back into a sentence using join().

• Example: 'I am George' -> ['I', 'ma', 'egroeG'] -> 'I ma egroeG'.

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

Lists are mutable, ordered collections; tuples are immutable, ordered collections in Python.

• Mutability: Lists can be modified (e.g., list.append(4)), while tuples cannot (e.g., tuple[0] = 1 raises an error).

• Syntax: Lists use square brackets (e.g., my_list = [1, 2, 3]), while tuples use parentheses (e.g., my_tuple = (1, 2, 3)).

• Performance: Tuples are generally faster than lists for iteration due to their immutability.

• Use Cases: Lists are used for collections of items that may ...read more

append adds a single element, while extend adds multiple elements from an iterable to a list.

• append(obj): Adds 'obj' as a single element to the end of the list. Example: lst.append(4) results in [1, 2, 3, 4].

• extend(iterable): Adds each element from 'iterable' to the list. Example: lst.extend([4, 5]) results in [1, 2, 3, 4, 5].

• Use append when you want to add one item; use extend when you want to merge another iterable into the list.

• Both methods modify the original list in plac...read more

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

Calculate the distance between two trains approaching each other one hour before they meet.

• If Train A travels at 60 km/h and Train B at 40 km/h, their combined speed is 100 km/h.

• In one hour, they will cover 100 km together before colliding.

• Distance = Speed x Time; here, Distance = 100 km/h x 1 hour.

Check if brackets in a string are correctly paired and ordered.

• Use a stack to track opening brackets.

• For each closing bracket, check if it matches the top of the stack.

• If the stack is empty at the end, brackets are balanced.

• Example: '{[()]}': balanced, '{[(])}': not balanced.

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.

Use super() method to call parent's init method in child class.

• Use super() method in child class to call parent's init method.

• Pass the child class and self as arguments to super() method.

• Access the parent class attributes and methods using super().

Variables are containers for storing data. Loops are used to iterate over a sequence of elements. OOPs is a programming paradigm based on objects and classes.

• Variables are used to store data in memory. They can be assigned different values and data types.

• Rules for naming variables: must start with a letter or underscore, can contain letters, numbers, and underscores, cannot start with a number.

• Loops are used to execute a block of code repeatedly. Types of loops include for lo...read more