The Top Applications Software Technology Interview Questions and How to Prepare for Them

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Toptal sourced essential questions that the best software developers can answer. Driven from our community, we encourage experts to submit questions and offer feedback.

Tell us a bit about the latest project you worked on. Was it finished successfully? If so, explain what you did to help make it happen and how you dealt with any problems that came up.

You should be able to tell a lot about the candidate’s overall contribution to the project, their management skills, and how well they work with others. This question should also show you how they interact with project management and other stakeholders. Software projects almost always run into problems and roadblocks. A software engineer or developer must be able to spot problems, solve them quickly and effectively, and complete the work correctly and on time. 2 .

Talk about a time when you had to make a critical decision during production. What happened? How did you manage it?.

The answer to this question will help you figure out if the candidate can think for themselves, quickly and clearly analyze and judge issues, and see the most logical connection between ideas.

People who are good at critical thinking often also like to explore new things. This can lead to new ideas and better ways of doing things. 3 .

How would you explain APIs to non-technical stakeholders?

Being able to communicate well is one of the most important skills a candidate can have. This kind of question will show you how the candidate deals with the toughest or most in-depth conversations.

A candidate might answer like this:

While this answer is accurate enough, it may come across as “just more tech-speak” to a non-tech-savvy audience. A better answer would be:

This is a little better. It sounds less academic, and some accuracy was given up in exchange for words like “website” instead of “web-based system” and “desktop software” instead of “software library.” But it’s still too technical because there needs to be a break to explain OSes, which some people may not know.

Compare that with:

Here, the answer gets across three key aspects of the topic:

• Everyone knows what it is: programmers, Twitter, and Windows are all well-known terms.
• What it does, using a concrete example. This example also uses well-known ideas: tweeting and putting something on a website.
• Building on the example and showing the “before and after” difference, this is why it’s helpful: it saves time and lets workers focus more on creativity instead of daily tasks.

That should help you figure out what to look for. If necessary, you can pick a technical term that you’re more familiar with instead of “API.” As far as communication goes, if your candidate’s answer wasn’t even right, that should be a huge red flag!

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Here is a simple programming challenge. Could you have a go at solving it?

Example question 1 (shorter time frame): Write a function to compute the Nth Fibonacci number.

For Example Question 2 (longer time frame), write a function that takes in the current position of a chess knight and gives back a list of possible moves that knight could make. That is, you don’t know where the other pieces are right now, so you can’t check to see if you can capture pieces on the knight’s side or leave their king open to capture. ).

Giving candidates a simple programming challenge may seem trivial, but it’s useful for several reasons:

• It gives you a chance to see how well they hold up under stress. You need to hire people who can write code under pressure, so make sure they do this in front of you.
• It demonstrates their educational foundation.
• It just shows how experienced they are and whether they can write code or not.
• It can help you tell the difference between skill sets depending on the type of challenge you pick. It also helps you figure out if they have a background in science or math and if they are a high-level thinker.

5 .

What programming languages do you use? Which three do you prefer, or are most familiar with?

This question will help you figure out how much the candidate knows about programming, how good they are at it, and if they are a good fit for your company.

Developers from all over the world use GitHub to share code. At the end of 2017, GitHub listed these ten programming languages and technologies as the most popular:

• JavaScript is a dynamic language that is often used to make websites more interactive.
• Python is a powerful, all-purpose language that became very popular in 2018. A lot of people use it for many things, like building websites, teaching computers to learn, and analyzing data.
• Java is a general-purpose programming language that is not related to JavaScript. It is used to make cross-platform apps.
• Ruby is an open-source, dynamic, object-oriented, general-purpose programming language that focuses on making things easy and quick. It’s mostly used for web apps, especially with the Rails server-side MVC framework.
• PHP is a server-side scripting language that is free and can be used to make web apps.
• The object-oriented programming language C is often used for games, operating systems, and embedded software. It can also be used to make more complex systems, like apps for managing devices and networks from afar.
• Cascading Style Sheets, or CSS, are an important part of the web and are used to format the text on web pages. CSS files help set important things like fonts, colors, layout sizes, spacing, and more. also make sure that the look and feel of different pages on a website stay the same.
• C# is an object-oriented language developed by Microsoft. It’s meant to make web development faster and easier, and it’s often used with XML-based web services on the NET platform.
• Go is an open-source programming language designed for building big, complicated software systems. It can also be turned into JavaScript and used in front-end web development, though this doesn’t happen very often right now.
• C is a high-level, general-purpose programming language. It was first made for writing system software, but these days it’s mostly used for making firmware or portable apps.

6 .

When you look over the code of another team member, what do you think are the most important things to keep in mind?

Code reviews are fundamental to the software development process, even when there’s only one engineer. This question will give you an idea of how knowledgeable and good at solving problems the candidate is, as well as how well they pay attention to details and keep the project in mind.

Here is a sample answer:

“I first look for security, functionality, and readability. Are the lines of code clear and concise, or are they crowded, bloated, and inefficient? How many lines of code that aren’t needed will I have to rewrite or get rid of? I look for any flaws that could lead to vulnerabilities and make sure that all regulatory requirements have been met. ”.

Each person has their own way of writing code, and each developer or team will have needs that are unique to their codebase. Effective code reviews often have checklists. Below is a limited list of general suggestions you could consider including:

• The software passes automated and manual testing
• Code follows applicable conventions and is easy to understand
• Code is not duplicated
• No negatively named boolean variables
• Scrutinize methods with boolean parameters
• Blocks of code inside loops are as small as possible
• No memory leaks

But more important than which exact points a candidate brings up is their reasoning for doing so. Watch out for candidates who get too excited about tabs vs. spaces and ignore more important engineering issues. The things listed above shouldn’t all carry the same weight. 7 .

Do you consider unit testing essential, or a waste of time?

Every engineer/developer worth considering should be familiar with unit testing. What they say in response to this question will tell you how they feel about it and how important it is to them in their work. Do they use behavior-driven development (BDD) or test-driven development (TDD)? Or are unit tests just something they add at the end to make sure the process is followed?

Unit tests are usually a part of a larger testing strategy. Most professionals in the field agree that they are the best way to maintain code and make software. They test for logic errors and coding flaws, helping to prevent bugs from advancing to the finished product. Plus, because they’re automated, they prevent regressions, where bugs return that had already been fixed. 8 .

What has your experience been like as part of an agile software development process, if any?

The Manifesto for Agile Software Development outlines an approach based on iterations rather than a waterfall model. Requirements and solutions are generated through the collaboration of self-organizing and cross-functional teams and their end users. Among other things, it encourages a flexible planning style and a rapid response to change.

If you know how a developer feels about agile development, you can figure out how they will fit into your own process. Developers with an open mind who can also see problems with how agile processes have been carried out can give you useful feedback that will help your team’s method grow and change.

If they’re set on stopping a key part of your process, on the other hand, they might not be able to stay productive. 9 .

How familiar are you with object-oriented programming (OOP)?

OOP has been the standard way to do things for more than 20 years. It is based on objects instead of actions and data instead of logic. People running for office have almost certainly come across it at some point.

Here are ten examples of terms they should be able to define:

• class, object (and the difference between the two)
• method (as opposed to, say, a C function)
• virtual method, pure virtual method
• class/static method
• static/class initializer
• constructor
• destructor/finalizer
• superclass or base class
• subclass or derived class

NB. Some firms avoid OOP and prefer to use a functional programming (FP) language such as Clojure. 10 .

Please explain big-O notation in the simplest terms.

Big-O notation (Landau’s symbol) is used in computer science to describe the performance or complexity of an algorithm. It describes how the runtime or space requirement of a function grows as the input grows.

It is likely that two functions that use the same Big-O notation will have the same growth rate, which means they will work about the same when given large amounts of data.

To give you an example, bubble sort takes O(n^2) time on average, while merge sort and heap sort both take O(n log n) time on average. Most of the time, merge sort and heap sort will work about the same, but they will both be faster than bubble sort.

Candidates should be able to demonstrate a basic understanding of the fundamentals of big-O algorithmic complexity analysis.

They should know that algorithms usually fall into the following performance classes:

• Constant-time
• Logarithmic
• Linear
• Polynomial
• Exponential
• Factorial

They should also be able to explain why a given operation falls into a particular complexity class.

There is more to interviewing than tricky technical questions, so these are intended merely as a guide. Not every good candidate for the job will be able to answer all of them, and answering all of them doesn’t mean they are a good candidate. At the end of the day, hiring remains an art, a science — and a lot of work.

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