Navigators Software Python Software Developer Interview Questions and Answers

Use the reverse() method to reverse a list in Python.

• Use the reverse() method to reverse the elements of a list in place.

• Example: my_list = [1, 2, 3, 4]; my_list.reverse(); print(my_list) will output [4, 3, 2, 1].

Use slicing with step -1 to reverse a string in Python.

• Use string slicing with step -1 to reverse a string: str[::-1]

• Example: 'hello'[::-1] will return 'olleh'

Using slicing to reverse a string in Python

• Use slicing with a step of -1 to reverse the string

• Example: reversed_string = 'hello'[::-1]

• Print reversed_string to see the reversed result

Use slicing with step -1 to reverse a string in Python.

• Use slicing with step -1 to reverse a string: str[::-1]

• Example: s = 'hello', reversed_s = s[::-1] will result in 'olleh'

Slicing in Python allows you to extract a portion of a string or list by specifying a start and end index.

• Use square brackets [] to specify the start and end index for slicing.

• The start index is inclusive, while the end index is exclusive.

• You can also specify a step value to skip elements while slicing.

• Example: reverse_string = 'hello'; reverse_string[::-1] will output 'olleh'.

Python decorator is a design pattern that allows you to add new functionality to existing functions or methods without modifying their structure.

• Decorators are denoted by the @ symbol followed by the decorator name.

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

• Decorators can be used for logging, timing, authentication, and more.

• Example: @my_decorator def my_function(): pass

Exceptions in Python are handled using try-except blocks to catch and handle errors gracefully.

• Use try-except blocks to catch exceptions and handle them gracefully.

• You can specify different except blocks for different types of exceptions.

• Use the 'finally' block to execute code regardless of whether an exception was raised or not.

Version control tools are software tools that help in managing changes to source code over time.

• Version control tools track changes made to files, allowing users to revert back to previous versions if needed.

• They enable collaboration among team members by providing a centralized repository for code.

• Examples of version control tools include Git, SVN, and Mercurial.

A system design for a messaging application like Whatsapp.

• Use a distributed system architecture to handle large number of users and messages.

• Implement end-to-end encryption for secure communication.

• Utilize a message queue system for real-time message delivery.

• Use a relational database for storing user data and a NoSQL database for message storage.

• Implement push notifications for instant message alerts.