Common coding mistakes happen to every developer, regardless of skill. That’s why you should know what they are, how to spot them, and how to avoid them.

It doesn’t matter if you’re a seasoned coder or a beginner, everyone makes mistakes. To grow as a developer, you need to be able to admit when you make one and you must also know how to fix it.

Yes, it’s possible to have a more experienced coder look over your writing to find those mistakes, and some tools can help you. But it’s much better if you can recognize when you’ve done something wrong.

In light of that, here are some of the most common coding mistakes that you may encounter during your sessions, and how to avoid or fix them:

What Are Some Common Coding Mistakes Made by Programmers?

1. To Remove Doubt, Comment

Comments are a crucial tool for any development project. Generally, coders include a comment to explain what a piece of code does, to leave notes or reminders, and sometimes to break up large snippets. Too many programmers forget to include comments in their writing, which not only hurts other developers but also themselves later on.

The opposite is also true, however, and some coders include too many comments. It can make coding projects more of a hassle, especially when you need to frequently edit comments after a change or update. This tends to happen when people “comment out” code, which means turning it into a comment to save it for later, that way they don’t have to rewrite the code if they want to use it again. You shouldn’t be commenting out code unless you know, for a fact, you’re using it soon.

A best practice is to include a comment for a snippet or line of code that’s not self-explanatory. For example, the “Display” command is an obvious one. But you might need to include a comment to explain precisely what is being output, especially if the variables used do not have detailed titles or names.

2. Use Smart Variable Names

Common practice is to abbreviate variable names to cut down on typing, which shortens a coding task. The problem with doing this is that either you or someone else, may not be able to recognize what that variable is, later. Data Scientists are often guilty of doing this. It’s one of the most common coding mistakes that leads to messy syntax and can also result in broken logic.

It’s best to be as detailed as possible with variable names, without ballooning the character count too much. Describe the information contained within the variable. For instance, instead of using something generic like “value,” describe what that value represents. You might use “total_customers,” or “incoming_revenue,” or whatever value it is.

You should also be using more descriptive names for temporary values and variables. Other people will be reviewing your code, so it’s worth investing the time to make it as easy to read and understand as possible.

3. Always Backup Your Work

It doesn’t matter where you’re working, online or off, or what IDE you’re using, always back up your work when you’re done with a session. If you’re working locally and offline, this is absolutely critical.

Data corruption, power failures, internet outages, and any number of unfortunate events could ruin your code or lose you hours of invested time. Make it a common practice to save multiple copies of your work. It may seem like a hassle or inconvenience, but when you need those back-ups you’ll be thanking yourself.

4. Choose the Right Language

Don’t choose a language just because it’s popular or because you’ve heard people say that it’s the best. Before you begin a project, look into the options that are available and choose one that best matches your needs and your coding style (related: best way to learn python).

If you’re a beginner, this step can seem daunting. There are quite a few languages that are excellent for novice coders, however, and you can always swap to another later. Besides, most of your work when you start your coding journey will be smaller, one-off projects and tests.

5. Keep the Syntax Clean and Consistent

Code is formatted a particular way, and it’s always for a reason. Most of the time, common practice is to keep it clean, organized, and easy to read. Try to make a habit of formatting your code consistently and properly. This not only keeps things simple for you but also anyone else reviewing the code.

If you use custom formatting, then be sure to keep your syntax consistent. For instance, maybe you like to include two blank lines between code segments? Perhaps you like to include brackets on the same line as the initial command? Both of those practices are fine, but keep doing it throughout the scope of your project. If you change things up, however minor, it can make reading and interpreting the language much more challenging.

6. Know the Common Coding Errors You’ll See

There are common coding error messages that you’ll encounter during your write-ups. From poor syntax to compiling issues, you’ll want to understand what each of the errors, or error messages, are trying to tell you.

• Syntax Errors – These errors occur when you’ve failed to properly write a command, close variables, and so on. IE) You forgot a closing parenthesis for a print command.
• Logic Errors – These are some of the most challenging to fix, and happen when your program or system’s logic is incorrect. You may not always receive an error either, but the returned values might be inaccurate.
• Compilation Errors – When converting your syntax into a low-level language the computer recognizes (this is called compiling), syntax errors can occur. You will generally see an error in the debug interface that denotes what happened.
• Runtime Errors – These errors occur anytime the application or software is running, which starts from the moment a user executes the program until it is shut down.
• Resource Errors – Most programs are designed to utilize a fixed amount of system resources. When those resources are unavailable, or they fail, a resource error will occur.
• Arithmetic Errors – Coding and mathematics are intertwined. When your math is off, you’ll see arithmetic errors, which have a strong correlation with logic errors.
• UI and Graphical Errors – While they are more related to the visual design side of development, UI and graphical errors do occur. Interface errors may also occur because of client-side interface discrepancies.

7. Avoid Using Unsecured Code

There are many cases where developers can leverage existing code or similar projects as a sort of shortcut. Many databases, or frameworks, for example, have continually developed code for use in other projects. This allows developers to call upon the frameworks and databases, without developing the necessary foundation themselves. Game engines are a perfect example of this, which contain code to handle in-game physics, major events, player interactions, and much more.

When you download and execute unsecured or potentially untrustworthy code, you are assuming there is nothing malicious contained within the data. Nefarious actors can modify code before or even after release, adding vulnerabilities and other dangerous elements. Applications that transmit and handle online connections are particularly susceptible to these kinds of exploits as hackers can spoof DNS and cache servers. This would allow them to modify code between OTA updates. 

The compromised code can affect your own projects, and may even harm end users over time. You should always use an integrity checking tool to verify the code before downloading. You should also consider doing this with your own code.

What is a Mistake in Code Called?

Coding mistakes may also be referred to as “bugs,” but it’s important to understand that not all bugs are related to human mistakes. Some bugs may occur due to logic failures after the application is compiled, and would have been invisible otherwise. Others are a direct result of human coding mistakes. Then, some carry over between systems, such as an IDE or framework that contains bugs, which make their way into other applications.

Typically, most bugs can be fixed through a software update.

Common Coding Mistakes: Everyone Makes Mistakes

Mistakes happen, and they’re natural. Even some of the most skilled and experienced developers make mistakes from time to time. What matters is that you know how to identify the most common coding mistakes, and how to fix them.

Every coder should create a process for editing their code and reviewing potential mistakes. You may want to get more eyes on the content, with colleagues or partners that are regularly checking your work. There are tools that will help spot potential issues, too. Most of the major development environments will return an error message or flag when something is wrong.

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