Devnaija Academy | 09-17-2024
Coding errors—they happen to the best of us. Whether you're new to programming or have been at it for years, mistakes in your code are inevitable. The good news? Most of these errors are easy to fix once you know what you want.
In this post, we’ll go over 15 common coding mistakes, explain why they occur, and give you quick fixes so you can get back to building awesome stuff without the headaches.
What is it?
These are the most basic types of errors and happen when your code doesn’t follow the rules of the language you're working with.
Why does it happen?
It’s usually something simple like a typo, missing a semicolon, or forgetting a closing bracket.
How to fix it:
Check the error message; it often tells you exactly what’s wrong and where.
Look for missing punctuation or mistyped commands.
If you’re using an IDE (and you should be!), it will highlight syntax issues as you type.
What is it?
This happens when your code tries to use a variable or object that hasn’t been given a value yet.
Why does it happen?
You forgot to initialize the variable or check if it’s null before trying to use it.
How to fix it:
Make sure your variables are initialized before you try to access them.
Add checks to ensure you’re not trying to use something that doesn’t exist yet.
What is it?
This sneaky error happens when your loops iterate one time too many or too few.
Why does it happen?
It’s easy to mess up loop start or end points, especially when dealing with zero-based indexing.
How to fix it:
Double-check your loop boundaries.
Remember, in most languages, arrays start at 0, not 1.
What is it?
This is when your loop just keeps running... and running... and running.
Why does it happen?
Your loop’s exit condition never gets met, meaning it has no reason to stop.
How to fix it:
Check that your loop’s exit condition can actually be met.
Make sure you’re updating variables inside the loop that are tied to the exit condition.
What is it?
This error pops up when you try to do something with a variable that doesn’t make sense, like adding a number to a string.
Why does it happen?
You’re using incompatible data types in an operation.
How to fix it:
Convert variables to the correct type before performing operations.
What is it?
You’re trying to access a position in an array or list that doesn’t exist.
Why does it happen?
You’re using an invalid index, usually because you didn’t check the length of the array first.
How to fix it:
Always check your array’s size before trying to access its elements.
What is it?
Your program is holding onto memory it no longer needs, slowly hogging all your system’s resources.
Why does it happen?
You’re not properly freeing up memory after you’re done with it.
How to fix it:
If you’re working in a language like C++, manually release memory when you're done using free() or delete.
In higher-level languages, use garbage collection or memory management tools.
What is it?
Recursion errors occur when a function keeps calling itself without stopping.
Why does it happen?
You forgot to include a clear stopping point in your recursive function.
How to fix it:
Make sure your recursive function has a base case that will stop the recursion.
If you don’t need recursion, consider using loops instead.
What is it?
You’re trying to use a variable in a part of your code where it doesn’t exist.
Why does it happen?
You declared the variable inside a function or block, but you’re trying to use it outside its defined scope.
How to fix it:
Check where your variables are declared and make sure you’re only using them within their scope.
What is it?
Floating-point numbers can’t represent every possible decimal value exactly, which can cause small rounding errors.
Why does it happen?
Computers have limited precision when dealing with decimal numbers.
How to fix it:
Avoid comparing floating-point numbers directly.
Use libraries or techniques that allow higher precision if necessary.
What is it?
Trying to divide a number by zero results in an error that will crash your program.
Why does it happen?
There’s no check in place to ensure the divisor isn’t zero.
How to fix it:
Always check that the divisor is non-zero before performing a division.
What is it?
Your program relies on external libraries or packages that are missing or incorrectly set up.
Why does it happen?
The required libraries aren’t installed or there’s a version conflict.
How to fix it:
Use package managers like npm or pip to handle your dependencies.
Check for missing packages and version mismatches.
What is it?
This happens when you accidentally mix up bitwise operators (&, |) with logical operators (&&, ||).
Why does it happen?
It’s easy to confuse bitwise and logical operators, or forget to use parentheses for grouping.
How to fix it:
Review the correct use of Boolean operators in your language.
Use parentheses to ensure the right grouping of conditions.
What is it?
You’re not handling errors in your program properly, so when something goes wrong, it crashes.
Why does it happen?
You didn’t anticipate certain errors or you’re catching the wrong type of exception.
How to fix it:
Always catch specific exceptions instead of using a catch-all approach.
Use try-except blocks (or equivalent) to handle expected errors.
What is it?
Your program runs fine, but it doesn’t do what it’s supposed to because of a flaw in your logic.
Why does it happen?
There’s a mismatch between what you want your code to do and what it’s actually doing.
How to fix it:
Step through your code and debug it line by line.
Use print statements or a debugger to see what’s going wrong.
Write tests to verify that your logic is working as expected.
How do you fix errors in coding?
First, understand what type of error you’re dealing with (syntax, logical, runtime, etc.).
Read the error message carefully—it often points you in the right direction.
Test small sections of code to isolate the issue.
Use debugging tools to track down problems faster.
How to avoid errors in coding?
Write clean, modular code.
Test your code regularly as you write it.
Do code reviews and use version control to catch mistakes early.
Use automated testing to minimize human error.
How can I avoid logical errors in my program?
Break down complex logic into smaller, more manageable pieces.
Write pseudocode or flowcharts to outline your solution before coding.
Use unit tests to verify that each part of your program behaves as expected.
Why does my code have so many bugs?
Bugs are normal, but they often arise from oversight, missed edge cases, or flawed logic.
Regular testing, debugging, and code reviews can help reduce bugs significantly.
What’s the difference between a runtime error and a logical error?
A runtime error will cause your program to crash during execution, while a logical error lets your program run but produces incorrect results.
Can coding errors be fixed automatically?
Some tools, like linters or certain IDEs, can suggest fixes for common errors.
However, not all errors can be automatically fixed, especially if they’re related to logic or complex operations.
Coding errors can be frustrating, but they’re also part of the learning and development process. The key is to know what kind of error you’re dealing with and how to fix it quickly. Happy coding!
Read More: 7 Easiest Programming Languages You Can Learn Today
