What are Software Bugs and How to Debug your Program?

by Carson
software bugs and debugging

As humans, we inevitably make mistakes. Therefore, programs always have errors no matter how professional the programmers are. So, we’ll talk about these software bugs and how to make your code free of them in this article.

Types of Bugs

Bugs are flaws in code that causes it to malfunction, return the wrong data, or prevent it from performing optimally. There are many types of software bugs that you have to learn about to become good at debugging.

Syntax Errors

Computers are not as smart as us when reading instructions. What they read must follow a strict grammatical rule, or the compiler or interpreter will not understand. Fortunately, these errors are quite evident and easy-to-detect since the program will simply display an error message when it runs.

For instance, if you use wrong symbol(s) or operator(s) like “==” instead of “=” for variable declaration, you will get a syntax error. Or, you may insert a dollar sign on your code, not within quotation marks. In that case, that may bring a syntax error, too, unless the programming language requires you to add “$” as an operator or keyword.

This will prevent the program from running further because it’s a fatal exception. The CPU will not even receive the correct executable code if your program contains syntax errors. If you are using that app, you will dislike it immediately and find an alternative.

How can a computer deal with a syntax error?
Image Credit: Canva
Logical Errors

Other than some errors that are very noticeable by the developers, some bugs are hidden behind. These are logical errors. The bug(s) will hide because it will not display error messages when the program runs.

The bugs include wrong control flow like a “for” loop that is supposed to be a “while” loop. Moreover, incorrect arithmetic statements in algorithms are these kinds of errors, too.

If these types of bugs appear, the computer will do the action at the wrong time, or execute the wrong program. That can lead to awful user experiences and incorrect values.

Arithmetic Errors

Moreover, some bugs include calculating the wrong value. For instance, if you mixed up “+” and “-“, you will have serious consequences when there’s something about money. Programmers take these earnestly, too, because they have to ensure that no values are wrong. Even a single arithmetic error in an app can bring significantly worse ratings!

Furthermore, there is a special scenario where a number is divided by zero. In that case, the program either throws an error or returns an undefined value or NaN. This is not what users want to see, and encountering NaN or “undefined” in the output is quite weird unless it’s a database.

Functional Bugs

Some bugs are about misbehaving functions in an app. For example, a simple login system takes your password into account. However, if wrong passwords are approved because of a bug in a boolean value, that’s a functional bug. That specific bug renders the entire login system obsolete and useless until the fix is released.

These errors are often noticeable but hard-to-find. Debuggers need to scan through the entire function or the malfunctioning part to find the wrong values.

Usability and Compatibility Bugs

Also, software bugs can involve compatibility and the usability of the program. For instance, if you don’t set the tag below:

<meta name="viewport" content="width=device-width, initial_scale=1">

…… your website isn’t going to be easy to use on a mobile device.

Moreover, usability bugs include the failure to make a good site/app navigation or simply unexpected errors when executing commands.

Furthermore, compatibility issues mean some parts of your code conflicts with the operating system or browser your program runs on. What does it mean? Well, the app may randomly become unresponsive or quit, or even crash the host system altogether.

Typos and Grammatical Mistakes

Finally, what users (and computers) don’t want to see are typos. For instance, if you type in a wrong variable name while you want to display something, it may throw a “NameError”. On the other hand, if the programmer made a typo when inserting keywords or arguments in the programming language, it will either throw an exception or return erroneous content.

On the other side of the issue, typos are easily discoverable by users. Sometimes, it may even be a sign that a website the code is deceptive and malicious.

Steps of Debugging

We spent a lot of time explaining the types of software bugs. Therefore, let’s talk about how to debug a program to get rid of those mistakes.

1. Run Your Program Frequently

When you’ve written a few lines of code after your last execution of your program, it’s time to do some testing again. Bugs will likely appear in that few lines. If you don’t locate the issue quickly, you’ll probably get distracted or even discouraged in a short time because you have to find a single error in a sea of characters.

Not working? Well, the next procedures are for you!

2. Inspect the Error Message

The first thing you want to do is to check the error message when you execute the code. You can get a significant view of your errors from that.

For instance, if the program stops and displays a “SyntaxError”, you will immediately know that grammatical mistakes exist in your code. You can even get the approximate location on the line number to speed up your debugging process.

Clues in error messages (Python)
Image Credit: Canva, Visual Studio Code

Note: You should skip this step if it’s a logic error. It will not display errors unless a number is divided by zero.

3. Locate the Issue

You must locate the issue to debug, right? That is the entire job on logical bugs, but it’s still useful when dealing with error messages. Remember that the trouble may only appear if the function is called, so the problem may be within the function, not in the call.

4. Look at Every Character

Start by looking at the wordings and syntax of the problematic area first. Once you’ve corrected this issue, you can test your code. However, if it still shows error messages, you may have a missing or unnecessary symbol or a typo.

In fact, a missing hyphen was the culprit of Mariner 1’s launch failure back in 1962. At that time, the spacecraft malfunctioned and accepted incorrect data, causing the rocket to malfunction. With that tiny character, an ambitious mission to Venus was destroyed completely. Fortunately, a backup probe in the same program, Mariner 2, reached Venus successfully.

Therefore, the example shows how important one single character can be! Therefore, do not ignore single-character mistakes — they may discourage you due to the difficulty of finding them and getting the code back to life!

5. If You Can Locate the Issue, Test the Fix

If you can see where the issue is, you’ve done a great job — immediately insert correct characters to prevent the bug from recurring. However, you never know if the program is correct — sometimes the fix of a bug causes another problem, while there may be multiple bugs in the file.

So, you have to hit the run button to test it, and make sure it has returned the correct value.

6. If You Cannot Find the Right Way, Don’t Afraid to Search the Web

If the problem recurs, especially if it returned the same value as before, your memory about this programming language might be a bit bland. Consider reading online materials to refresh your knowledge about those functions. Otherwise, you may want to execute something that you haven’t learned yet, and searching the web is the solution.

Moreover, look for forum posts that have exactly your problem. Therefore, search the entire error message excluding things related to the filename of the program, your username, or any other sensitive information.

Therefore, don’t afraid to search the web to prevent you from looking unprofessional. Remember that you always learn new things every day, and you should not reject to do so while debugging!

7. If You Still Have Problems, Don’t Afraid to Ask

If you have problems that you cannot resolve using existing resources on the web, try searching for broader keywords and scrolling down a few pages. If you still can’t find the solution, ask your teammates, friends, and contacts — they may have the answer for you.

If neither of your circle has the answer that works properly, it’s time to ask questions in forums like Stack Overflow. You might receive a reply in a short time if someone else in the world has the same problem and solved it. Of course, your question likely won’t be discovered unless someone else runs into the same error, but it’s worth giving a try.

8. If Bugs Appear Only Occasionally, Consider Error Handling

Sometimes, you may have trouble replicating the bug because it may only appear in some pretty rare circumstances. In this case, consider error handling when you cannot even locate the bug. They are useful in programs, especially programs that cannot prevent an error from being created if a specific condition is met. That way, if you run your app and it crashes, it can still display a message or send a debug report and try to go on instead of crashing abruptly.


So, we’ve talked about common types of software bugs in programs, and how to debug programs to make it mistake-free. We hope you have a good coding experience and avoid errors as much as possible in the first place!

References and Credits

  1. Andrew C. Pincher. (2020, December 9). 7 types of software bugs and errors | The JotForm Blog. Retrieved February 9, 2021, from https://www.jotform.com/blog/types-of-software-bug/
  2. (2020, June 29). Types of Bugs in Software Testing: 3 Classifications with Examples. Retrieved February 9, 2021, from https://www.scnsoft.com/blog/types-of-bugs
  3. (2021, January 18). 7 Types of Software Errors That Every Tester Should Know. Retrieved February 9, 2021, from https://www.softwaretestinghelp.com/types-of-software-errors/
  4. (2016, October 4). 10 common Software Errors and Bugs to watch for. Retrieved February 9, 2021, from http://blog.mallow-tech.com/2016/10/10-common-software-errors-and-bugs-to-watch-for/
  5. (n.d.). NASA – NSSDCA – Spacecraft – Details. Retrieved February 9, 2021, from https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=MARIN1

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