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Tips to write bug-free code during interview

Tips to write bug-free code during the interview

Coding interviews are tough. We said it, they are hard to crack and prepare but still every year thousands of developers beat them to get into their preferred jobs in their favorite companies. They do it by writing bug-free code. Let’s find out some tips and practices that you can implement to crack a coding interview and write bug-free code.

Interviewers or the reviewers of the code that you write during your selection process are those who rate your code and decide whether you are prepared for the job or not. So knowing their expectations is essential. Though different interviewers look for various aspects of the code, the thing that every interviewer looks for is that if you are highly organized in your approach to the problem. It not only rates you as a good and logical developer but also as an employee they would enjoy working with. A significant aspect of the code that is a necessity for all interviews is writing bug-free code.

Why is it important to write bug-free code? 

Writing bug-free code is given higher importance because problems put up to you are mostly straightforward. Recruiters are looking for a person who has control over basics but is also creativity. Developing a simple program may sound easy, but with hundreds or maybe more people competing with you for the same job, you need to make sure that your code is flawless.

Tips for writing bug-free code:

Understanding the problem:

Before you start typing away, understand the challenge put in front of you. Coding interviews look like a race against the clock for those who miss out planning what their approach to the problem would be, as they never completely understand what it is. Take the first few minutes to explain to yourself how the whole program would look like and what all procedures you would write, principles you will use. You don’t need to think every line of code here itself, that’s something you can as you go on. Just having an overview of the whole program that serves as a solution to the problem would do the job. Better planning and understanding will induce lesser tension and confusion so that you can write bug-free code.

Write short and focused functions

No one likes reading functions that are long and do multiple operations which are not dependent. Remember to be concise while coding, you need to write the program in the least possible lines. Also, make sure you don’t overrule the single responsibility principle that states that a function should have responsibility for only a single part of the functionality. Don’t try to solve the whole problem into one big block of code, instead split it into multiple single functionality parts. Shorter codes that focus on only one functionality are easy to read and understand, while the probability of making error majorly decreases.

Follow clean nomenclature

While you are at a coding interview, you are at high stress, and load to not only solve the problem but also complete it in time. Remembering what name you gave for a function or a variable several lines above is just something that will make you either lose time or make mistakes. I don’t want both to happen, so always name your variables, functions, or classes simple terms that are easy to remember and do not have confusion conflict with other terms.

A meme showing how coders dont use correct variable naming conventions

Focus on Design

What most developers miss during their interview is that your tendency to make errors decreases if you follow one design pattern explicitly. This design pattern should resonate with your solution approach. Write clean code by taking care of minor but essential aspects like the spacing between lines of codes or the maximum length of a line. To make your code bug-free follow that OOP Design Principles, a set of principles that will guide you to write code with higher design quality.

Keep explaining your approach and commenting

We’ve discussed lots of time before that nobody likes comments most of the time in our software, but as a recruiter, we look for comments in someone’s code to know what thoughts did they have on any problem. While commenting is for the interviewer, you as a coder must keep explaining your approach to yourself. It helps you write better comments while also giving you a reference on what you thought of doing and what you did. This way, you can check your codes as well for any errors you may have made. Comment concisely and refrain from explaining too much or the whole procedure. If any principal or method name as a reference can define what you did in your program, it will be enough.

Keep your basics strong

As discussed above, coding interviews are rarely complicated and have problems that can be solved using basic operations. As a recruiter, I expect you to be a great learner as soon as you join the organization and that can only be possible if you have an excellent grasp on your basics. Revise all the methods and procedures a day before you appear for an interview. Another advantage of this tip is that screwing programs made from the basics of development is quite hard. Your application will be free of errors and bugs this way.


What impresses the interviewers the most is when someone uses TDD or Test Driven Development process for their problems or every program of the problem. This process has such high importance for writing bug-free codes that should be included in your daily practice. TDD is a test that is done while writing codes and hence sometimes called Test-First Development. In this, you develop tests for all small functionality of your software to see if it passes or not. If it passes, then your code is bug-free, and you can move on without any further inspection for that specific function. If it fails the test, refactor that function, and try again. TDD also decreases duplication, removes the code smell, and for a recruiter makes a statement on how much a developer focuses on the quality of software.

Take it cool before an interview

A stressed mind makes more mistakes. This applies to all interviews and not just coding. You need to be relaxed and comfortable before appearing for an interview so that you are in the least pressure and make less silly mistakes. Try arriving near to the location of the interview 20-30 minutes before the scheduled time, so that you have good enough time to rest and also adapt to the test location. But don’t yet go to the place as it would annoy some recruiter, and you know the saying – first impression is the last impression. 
Eat light and drink less before an interview. Do not skip the meal entirely; an empty stomach will make bad decisions for you. Wear something that you feel comfortable in as well as does comply with the dress code; stressing over appearance is the last thing you need.

A woman trying to write bug free code

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Writing bug-free code is not an easy task; doing that at an interview is much more difficult. The interview brings added pressure, stress, and load on developers that they can eliminate if they follow some tips that involve understanding problem statements, writing clean code, commenting, following principles of design and testing. Following these tips will give you a higher chance of writing bug-free code at interviews, cementing your position as one of the employees at a job you wish to be! What all the practices do you follow when you sit for a technical interview?


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