How do you troubleshoot bugs in your code?

This question is asking about your problem-solving ability and process, specifically in regards to how you debug or troubleshoot problems within your code. The interviewer wants to see that you have a systematic methodology for diagnosing and solving problems. It is highly recommended to:

1. Outline your approach in a step-by-step manner showing how you isolate and then solve problems.
2. Provide a example showcasing when this approach was beneficial.
3. Discuss tools and/or strategies you have found most helpful in fixing bugs.

Once I encounter a problem in my code, my initial step is to reproduce that bug consistently. Understanding the steps to replicate the issue can offer insights about what's going wrong. Then I will look at my error logs to help pinpoint the bug. If the error still is not clear, I'll use debugging tools to guide me towards the source of the problem.

Once the bug is isolated, I resolve the issue and test the expected vs actual result to ensure that it was the only issue. As an extra precaution, I will also do regression testing to ensure my fix hasn't affected anything else. A good instance of this was when I was working on a project where the application started crashing after a recent update. By following the steps above, I realized the crash was due to a memory overload problem. After fixing the bug and running a regression test, everything was back on track.

When debugging my code, my process is methodical. Firstly, I aim to understand the issue at hand by gathering as much information as possible. This could include error or crash reports and user descriptions. I then attempt to reproduce the problem and inspect the code in that area.

I prefer a 'divide and conquer' approach by breaking down code into smaller segments, and using a combination of print statements and breakpoints to identify the problematic area. When the bug is found, I address the error, and then verify my work by doing a thorough testing. Afterwards, I commit my changes with an informative message describing what was done to solve the issue.

Once, while working on a complex application, the users reported a random crash. Using the approach described above, I managed to identify that the problem was with a particular API we were using that was occasionally returning a null value, and I then put checks to handle those exceptions.