Before you start scouring job boards and applying to positions, it’s a good idea to be prepared with answers to the common interview questions you may encounter when speaking with Python developers. A recent Stack Overflow survey found that nearly half of developers have been asked What’s your favorite data structure or algorithm? or some variation of this question during an interview, so it’s smart to be ready with an answer just in case! This article will give you sample answers to many common Python-specific questions, as well as best practices for responding and tips to guide your preparation.
1) What is the maximum length of a string in Python?
Strings in Python are represented internally as Unicode code points. The maximum length of a string is, therefore, defined by Unicode’s maximum code point—which is currently (Version 10.0) about 65,000 characters. And that’s not counting byte-order marks (BOMs), which can potentially extend string length even further.
2) What is the difference between == and is operators in Python?
The == operator compares whether two variables have equal values. The is operator is more complicated: it returns True if an object is of a certain type, or False otherwise. You can use it to see if one variable contains another variable; you can also use it to check if a variable represents some other kind of objects, such as a list or class instance. In order to understand which operator to use when you must learn about reference and value comparisons.
3) How would you sort an array of integers from least to greatest?
This is one of those interview questions that’s super easy to answer if you’ve already got a bit of experience coding in Python. The challenge: coming up with it on the spot! To solve it, we’ll use an algorithm called bubble sort. It works by comparing each value in our array with its neighbors until it finds two elements that are out of order; then, it swaps them.
4) What is the difference between range(0,10) and range(1,10)?
The difference between range(0,10) and range(1,10) is that range(0,10) returns an iterator of numbers 0 to 9 inclusive. You could use it in a loop and modify each value sequentially but not know what number you’re on since incrementing will continue until it hits 10. But range(1,10) returns an iterator that starts at 1, incrementing until it reaches 10.
5) What are true division, floor division, and integer division in Python?
In computing, the division is an arithmetic operation that performs the division of one quantity by another. The dividend is divided by the divisor to produce a quotient and a remainder. For example, in 6 ÷ 2 = 3 with a remainder of 1, and 15 ÷ 3 = 5 with no remainder. Both 6 and 15 are whole numbers (also called integers), so their division results in a whole number.
6) Give an example of list comprehension.
List comprehensions, a feature of python that allows you to apply an operation to every element in a list and return it as a new list. This is one of those features that can easily go unnoticed in your day-to-day programming because they are concise, very efficient, and don’t require much documentation. However, I believe they deserve special mention here due to their utility when doing certain kinds of analysis on data.
7) Explain how lambda works.
Lambda is a powerful and concise way to create small inline functions. Lambdas are similar to but more concise than anonymous functions. They can make your code more expressive without sacrificing its readability. Let’s have a look at an example that makes use of lambda. The following snippet shows how we would write a function using an anonymous function.
8) Explain how tuple unpacking works.
Tuples in Python are used to store multiple values in a single entity. When a tuple is used within an expression, each value from that tuple can be referenced by name as if it were a separate variable.
9) Can you do nested list comprehensions? If so, how would you do them?
Nested list comprehensions offer a concise way to create list objects from other lists, where each element of the output is determined by an expression. The two examples below show how you might use nested list comprehensions.
10) What does this code output?  + 3 *  + 1 .[1, 6, 7] Don’t forget to include a brief explanation. What is a heredoc? (See example) What is a CSV file? What does it look like? How can you open and read one in python? Explain what each element in the list does when looping over a list.
11) Draw the syntax tree of 2+2*3. And then explain what happens when you do it again
The syntax tree of 2+2*3 is as follows: There are two operators, + and *. Each of them has two operands. The first one is 2 and 2, which are respectively op1 and op2. The second one is * and 3, which are respectively op1 and op2. By doing operator overloading in python, it will help us use different types of operation objects with the same syntax tree in a much more readable way.
12) Write a function to add two numbers
Functions are at the heart of any programming language, and your first interaction with a new language should be learning how to write functions. Write a function called add_numbers that accepts two arguments (numbers) and returns their sum. So, if you input 1+2, your function should return 3. If you pass in 1+1 when you only define one argument, it should return 2.
13) What’s the difference between list and tuple?
A tuple is an immutable data structure and is used to represent an aggregate value. Lists are mutable which means that they can be modified. A list consists of elements separated by commas, while a tuple consists of items separated by commas or enclosed within parentheses, brackets, or braces.
14) What happens when you print non-integer using the int() function?
This is one of those questions to find out how deep do an applicant’s understanding of basic data types and built-in functions goes. This question demonstrates that you know integers are a primitive data type in Python and that int() is a function that converts its argument to an integer. For example, int(1.2) returns 1, while int(‘foo’) returns an error because strings cannot be converted to integers.
15) What are different ways of filtering in Python?
There are many ways to filter your data in python. There is no right or wrong way to do it, but there are many approaches that fit a variety of scenarios and programming techniques. The best option will depend on your scenario and even your personal preference. Let’s look at some of these filtering techniques to help you determine which method is right for you next time you need to filter data in python.
16) How would you find 2 given numbers in an array/list without duplicates?
There are several ways to solve it, one of them would be: def find_unique(numbers): lower =  for number in numbers: if number not in lower: lower.append(number) return lower print find_unique([4, 1, 5, 3]) ## >>> [1, 4]
17) How would you sort nested lists using built-in functions?
Lists can contain nested lists. This is a common problem for beginners but with practice, it’s easy to create complex data structures. Although there are plenty of functionalities and methods available for manipulating arrays in Python, you’ll sometimes need to use built-in functions instead. One of these functions is the sort that sorts lists from lowest to highest or vice versa if you provide it with a negative number.
18) How do you check if an integer is an even or odd number?
A simple method is to just try dividing by 2. If it’s an even number, then you will get 0 as a result, otherwise, if it’s odd, 1. But it is always better to write a program rather than rely on a manually calculated output. First, let’s import some libraries and create our function which will return True or False
19) Can we use lambda with open() and filter() built-in functions?
Like other programming languages, Python also supports lambda functions. This allows us to implement anonymous functions in our code. The lambda keyword is only used for creating lambda functions. There are two types of lambda functions in Python: basic lambda function and Multi-Line Lambda Function. In addition to that, we can also use the callback function as an anonymous function with filter() and max() built-in functions in Python. Let’s check out the top 8 interview questions about lambdas to ace your next interview!
20) Which test case fails at runtime? Why?
Unit tests help you verify and validate code at a small scale, with isolated components. By running these tests prior to checking in code changes, you can ensure that your changes haven’t broken existing functionality. If all of your test cases pass but something is still amiss, then it’s time to take a look at what happens when your code is deployed to production.
While the job market and demand for Python developers have continued to grow in recent years, getting interviews and job offers can still be difficult if you’re new to the field or don’t have much experience working with Python. The above 20 questions are some of the most commonly asked during technical interviews, but knowing them well and being able to respond thoughtfully will help you stand out from other applicants and increase your chances of landing your next job as a Python developer. If you are interested to learn new coding skills, the Entri app will help you to acquire them very easily. Entri app is following a structural study plan so that the students can learn very easily. If you don’t have a coding background, it won’t be any problem. You can download the Entri app from the google play store and enroll in your favorite course.