How to Debug Python Code Effectively (Beginner to Pro)
Every developer, from beginner to experienced pro, encounters bugs. Debugging is the process of identifying, locating, and fixing these issues in your code. In Python, debugging doesn’t have to be painful—especially if you know the right tools and techniques.
This guide will walk you through effective ways to debug Python code using built-in tools, best practices, and pro-level strategies.
Why Debugging Matters
Debugging is more than just fixing errors — it’s about understanding how your code behaves. Strong debugging skills can:
- Save hours of frustration
- Help you learn programming concepts deeply
- Lead to better, more reliable software
1. Start with Clear Error Messages
Python provides helpful tracebacks when errors occur. Read them carefully—they often tell you:
- The type of error (e.g., TypeError, ValueError)
- The file and line number
- A message explaining what went wrong
Example:
python
Copy code
print(“Total is: ” + 100)
Error:
python
Copy code
TypeError: can only concatenate str (not “int”) to str
Fix:
python
Copy code
print(“Total is: ” + str(100))
2. Use print() Statements (Beginner Technique)
Add print() lines to check variable values or program flow.
python
Copy code
def divide(x, y):
print(f”x = {x}, y = {y}”)
return x / y
This is quick and useful for small problems, but not ideal for larger codebases.
3. Try pdb – Python’s Built-in Debugger
pdb lets you pause execution and inspect variables line by line.
Add this to your code:
python
Copy code
import pdb; pdb.set_trace()
Then run your script. You can now use commands like:
- n — next line
- c — continue
- q — quit
- p variable — print value of a variable
4. Use try / except Blocks Wisely
Handling errors with try/except helps narrow down where things are failing:
python
Copy code
try:
result = divide(10, 0)
except ZeroDivisionError as e:
print(“You can’t divide by zero!”, e)
Don’t overuse this to hide bugs—use it to handle expected exceptions.
5. Use an IDE with Debugging Features
Modern editors like VS Code, PyCharm, or Thonny offer:
- Visual breakpoints
- Step-by-step execution
- Variable watchers
- Call stack viewers
These tools are essential when working on large projects.
6. Write and Run Unit Tests
Writing tests using pytest or unittest can help you catch bugs early and identify exactly what’s failing.
7. Rubber Duck Debugging
Explain your code to someone else (or even a toy duck). Speaking your logic aloud often reveals mistakes or assumptions.
Practice Challenge
Try this:
Create a function that processes user input and intentionally includes a bug. Use print(), try/except, and pdb to find and fix it.
Debugging small, controlled problems builds your confidence for handling real-world code.
Want to master Python development from writing code to debugging and deploying apps?
👉 https://www.thefullstack.co.in/courses/
We offer full tracks with practical projects, mentorship, and personalized help to level up your skills.
You might be like this:-
What is AWS Lambda?A Beginner’s Guide to Serverless Computing in 2025
Java vs. Kotlin: Which One Should You Learn for Backend Development?
Leave a Reply