8 Coding Interview Questions and How to Answer Them

Coding is the foundation that machines need to function. When a computer or machine utilises a code, it follows instructions to execute a task properly. But the machine can't do it alone. Someone is needed to write the code.  

If you have a computer science, programming, and coding background, you may look for jobs that put your skills to good use, such as a career in web development or computer engineering. Here are eight coding interview questions that an organisation might ask you during a job interview, as well as the best way to answer them to impress your potential employer and secure the role.

1. Tell me about yourself

What they’re really asking: Why are you interested in this position?

In any job interview, the first question usually acquaints you with the interviewer. They first want to know who you are, where you come from, and why you want the job they’re offering.

You can introduce yourself in various ways, but remember that you want to start the interview strong and give a glimpse of your working background and who you are as a person and a worker.

To start, introduce yourself with your educational background and explain why you got into the world of coding. You can reference past roles you’ve had, your interest in coding, and why you sought this role. Keep this answer concise and straightforward, but don’t be afraid to talk about yourself, as that is exactly what they’re asking you to do.

Other forms this question might take:

• What is your educational background?

• Tell me about your prior work experience

• What makes you qualified for this role?

2. What are some programming projects you’ve worked on?

What they’re really asking: Do you have programming experience?

Potential employers want to understand what you already know and what they need to teach you. They might ask about specific experiences you’ve had and how you felt about them.

Your answer should include specific details and show off your knowledge of the coding field. Tell the interviewer about a specific project and what you learned from it. For example, if you worked on a programming team, describe what that looked like and how it was to work with other people. If you were more independent in a previous role, explain the pros of coding alone, discovering new technology, and your approach.

Other forms this question might take:

• What is your programming background?

• Is there a specific programming project you’ve completed that you’re proud of?

3. What programming languages are you familiar with?

What they’re really asking: What is your background in programming?

Once the interview is more professional, they will likely ask you about the specific programming technologies you know best. You’ll want to provide as much information as possible.

Some of the most common and in-demand programming languages are:

• HTML

• Java

• C Language

• Python

• Rust

• Perl 

• JavaScript

• C#

You may be familiar with a few or several coding languages, but no employer expects you to be proficient in everyone. When answering, explain which languages you are most knowledgeable in and which you prefer to use. This will give the employer an idea of what you’re used to, how you work, and which skills or languages you still need to learn. 

Other forms this question might take:

• What programming language are you most proficient in?

• How many programming languages do you know how to use?

4. What is the importance of software testing?

What they’re really asking: Do you know the value of this role?

Software testing is an important part of the development process because it allows the tester or developer to detect bugs and other possible problems within the software and its coding. When you test your software before launching it, you ensure a higher quality product and eliminate the risk of a threatening bug or glitch. 

An interviewer will examine your answer to predict whether you respect the process of testing software or tend to overlook it. Your knowledge of the importance of software testing could set you apart from other candidates when working towards a career in coding and reinforce your dedication to the process.

Other forms this question might take:

• Tell us about your experience with software testing

• How important is software testing to you?

5. What is the difference between searching and sorting?

What they’re really asking: Can you define different aspects of programming languages?

Searching an algorithm is locating a specific item in a much larger collection. 

When searching the algorithm, you must know the specific items you want. For example, you’ll need to input a name or code specific to the item you’re trying to find. Upon identifying this item, a pointer, also known as the address or home of the item, is returned so you know where to locate it in the future. You won’t know where the item resides if nothing is identified. 

Alternatively, sorting is when you place items in a specific order. You can sort them in several ways to make sense in the algorithm, such as alphabetically, numerically, by likeness, or something else. 

In an interview, the employer will want to know that you clearly understand the difference between searching and sorting and the skills to perform each type of task. This also helps them understand that you are knowledgeable about industry terminology.

Other forms this question might take:

• What is searching?

• What is sorting?

• How do you locate a specific item in an algorithm? 

6. What are the important features of an algorithm?

What they’re really asking: Do you understand the importance of certain programming features?

An algorithm is an essential part of programming. It is the process that the computer follows to complete a task, and must have the following characteristics or features:

• Clarity

• Input and output

• Finiteness 

• Effectiveness

Explaining the important features of an algorithm will further prove your understanding of programming and coding.  This knowledge can also give the interviewer an idea of how you complete a particular task and solve possible problems. 

Other forms this question might take:

• Describe an algorithm

• How do you solve problems within an algorithm? 

7. How do you reverse a string?

What they’re really asking: Give us an example of how you code

Reversing a string is another important part of the coding process, and it's often one of the most common interview topics. It shows off your technical knowledge, and it is another question that will help show off your problem-solving skills.  

Each programming language has a unique answer to this question, so when asked, you should use the language you are most proficient in to answer unless the interviewer specifies otherwise.

For example, if you are most familiar with Java, you would explain how to reverse a string in Java. Also, keep in mind that interviewers with organisations that use Java exclusively will almost always ask this question because of the diversity of potential answers.  The best way to practice this type of question is by performing the task beforehand and familiarising yourself with the different ways. 

Other forms this question might take:

• Are you familiar with reversing a string?

• What is the importance of string reversal?

• Describe a time when you had to reverse a string

8. How do you identify and solve problems in a code?

What they’re really asking: How do you problem solve?

Everyone solves problems differently, but when an interviewer asks how you identify and solve issues within a code, they look for your specific process and how creative and self-aware you are when carrying it out. They may even give you a specific problem to solve.

Once you’ve identified and solved the problem, you’ll want to revisit it and find another approach. This will involve giving multiple answers to the cause of the issue and multiple solutions to fix it. This will demonstrate that you put a lot of thought into the code and understand the issue's complexity.

Other forms this question might take:

• How do you handle stressful situations?

• Do you have experience identifying and solving problems with code?

Prepare for your interview

Acing your interview starts long before you meet your interviewer face-to-face. Preparation looks different for everyone, but here are some ways you can get ahead:

Research the company

Companies want you to be familiar with them before the interview, but they don’t need you to tell them who you are. Instead, understand what the company does, why you’d like to work for it, and what you can offer to further its mission.

Research the role

To determine whether or not you’re a good fit for the role you’re applying for, spend some time familiarising yourself with it. Ask yourself: Do I meet the qualifications? Does this sound like something I want to do? 

Rehearse your interview

A mock interview is a great way to prepare for the real thing. Ask a friend or colleague to practice with you by asking interview questions about coding jobs. You may also want to attempt these practice coding problems to understand better what an employer may seek.

Next steps

To further prepare for a career in coding, consider specialised Coursera credits and certificates such as Computer Science: Programming With a Purpose offered by Princeton University or Python for Everybody Specialisation offered by the University of Michigan. Explore the Interviewing and Resume Writing in English Specialisation by the University of Maryland on Coursera for more information and resources on interviewing tactics.