Effective Strategies For Debugging Code

Debugging a code is a tedious task. Even if you use the best debugging tools, you won’t be able to debug a program if you don’t approach it strategically. In this article, we will discuss different debugging strategies that you can use to solve errors in your code. For this, we will first discuss different types of bugs and the common difficulties we face while debugging code. Finally, we will discuss some debugging techniques to help you debug your code in an easy manner.

What Are The Different Types of Bugs in a Program?

Bugs are introduced to a code due to various reasons. Based on their origin, we can classify bugs into the following types.

1. Syntax and Type errors: Syntax errors arise due to errors in writing code according to the syntactic structure of a programming language. Similarly, type errors occur in a program when we assign values of incompatible data types to a variable.  Syntax errors and type errors are easily detected by a compiler and are one of the easiest errors to debug.
2. Typing errors: Typing errors are those errors that are syntactically correct and pass undetected by the compiler. However, they lead to erroneous output. Examples of typing errors include missing parentheses in mathematical expressions, accessing the wrong index of arrays, wrong comparison operators in conditional statements, etc.
3. Logical errors: If the logic we use to implement a program is incorrect, we get severe bugs. If we don’t cover all the use cases while designing the algorithm, the program will run into an error if it encounters a corner case. If the algorithm is logically flawed, we must rethink and redesign the algorithm to make the program work correctly.
4. Implementation errors: Even if the algorithm used to implement the code is correct, there might be errors due to erroneous implementation. If a data structure is manipulated incorrectly or units of physical quantities are different, the program will run into error. These errors are hard to detect but can be very fatal. For example, you might have read about how NASA lost a Mars climate orbiter due to using the FPS system instead of the Metric system in their codes.

Common Difficulties We Face While Debugging Code

While debugging a code, we normally use the following steps.

1. First, we try to reproduce the error.
2. Next, we analyze the code and test it using different ways to identify the root cause of the error.
3. After identifying the cause of the bug, we fix it by making changes to the code.

The above steps might seem trivial but we often run into problems while debugging a code. Following are some of the common difficulties we face while debugging a code.

• The bug cannot be reproduced easily: To understand an error in a better manner, we need to reproduce it. If we are not able to reproduce a bug, we cannot analyze it. Mostly, we find difficulties reproducing bugs if the program uses multithreading. In such cases, the error might occur only in particular interleaving of statements from parallel threads. To reproduce the error, we need to reproduce the exact interleaving of statements.  This is hard to achieve as scheduling the execution of threads is not in our hands.
• Inability to identify the cause of the bug from the error log: We cannot always find the root cause of an error by observing the error logs. This is due to the reason that the cause of the error can be remotely connected to the statement that runs into error. For example, if you import a module and it contains some error, you might not be able to identify where the error occurs in your code. Even if you do everything right, your program will run into an error as the bug is in the imported module. Hence, identifying the root cause of an error can sometimes be a difficult task.
• Correlation between the errors: There can be multiple errors in a code snippet. Hence, when we fix an error, we might get another error and the error message will change. Then, we will need to re-examine the error log again to identify the new issue. This might get very frustrating.
• New errors after fixing existing errors: If we don’t find the root cause of an error and fix it using shortcuts or hacks, it is highly likely that the program will run into another error. Hence, whenever we find a bug, we should try to find the root cause of the bug and change the logic or implementation details instead of trying hacks. Otherwise, we will keep getting new errors.

Effective Debugging Strategies You Can Use To Debug Your Code

There is no handbook containing specific steps for debugging. However, we can use certain strategies to effectively debug a code without getting into very much trouble. The following list contains some of the effective strategies for debugging code.

Use Preventive Measures to Minimize Errors

Prevention is better than cure. We should try to write code in such a manner that minimizes the possibility of bugs. ‘

• Following coding practices and naming conventions will help you avoid syntactical or typing errors. 
• You can use test-driven development to cover edge case scenarios and avoid logical errors.
• You should also try to develop the program incrementally and test modules one by one. Once you write a code module, you should test it functionally. Once you have tested a module for all the test cases, you can be sure that there is no bug in the particular module. After unit testing, you should integrate the current software module with other modules and test them as a whole. If you follow this process, searching for bugs will be localized to newly developed modules and you will be able to fix bugs easily. While integrating codes of different modules, you should always use proper code refactoring techniques to avoid errors.

Implement Logging in Your Code

Every programming language provides tools for logging. You can log information about program execution and stack trace of the error. This will help you identify the cause of errors easily when your program runs into a problem. Hence, always try to implement logging in your code.

Use Assertions While Debugging

While debugging the code, many programmers use print statements. This isn’t a very efficient approach. You should always use assert statements to check the value of variables or return values of functions while debugging. This will help you identify errors as soon as they occur. Remember that you cannot use assert statements in the actual production environment. Use it only while you debug the code.

Use Debugging Tools For Better Workflow

Debugging tools make your life easier by providing tools for setting breakpoints in the code, inspecting the variables, and watching the program expressions at a specific stage. You can get all the runtime information about variables and functions while debugging using dedicated tools. This will help you expedite the debugging process in an effective manner. Here is a list of the best debugging tools in Python programming language.

Simplify Complex Problems into Smaller Tasks

If you are getting an error in a software module, try to test the functions, classes, and methods in the module to identify the error. If you are getting an error in a block of code, try to run the statements in the block of code one by one. This will give you an easy way to identify and rectify the errors.

Ask For Help From Your Teammates

Many times, we aren’t able to see our own mistakes. In such cases, you might spend hours on a simple bug generated from a silly mistake without achieving anything. Hence, if you are not able to identify and eliminate the bug, you should consider asking for help from a teammate.

Cluster Bugs According to Their Nature

If you get a large number of errors in your code, try to cluster the bugs based on their origin. It is possible that bugs raised from a single function or class have a single root cause. Hence, fixing a single error can solve many bugs and you will save time. Thus, you should consider bug clustering if you get a lot of bugs in your code.

Take a Break If You Are Stuck While Debugging

If you are stuck solving a bug for hours and you don’t know what to do, get a break. You can have tea or coffee and refresh your memory. After taking some rest, you can start again with a fresh perspective on the problem that can help you solve the bug easily.

Conclusion

In this article, we discussed different types of bugs in a code and what are the difficulties while debugging them. We also discussed different strategies for effective debugging of the code. 

To learn more about coding, you can read this article on code documentation techniques. You might also like this article on bad data visualization examples.

I hope you enjoyed reading this article. Stay tuned for more informative articles.

Happy Learning!

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