Python Debugging Like a Pro: Using pdb and PyCharm Debugger

Introduction

Debugging is an essential skill for any Python developer. Whether you’re a beginner or an expert, encountering bugs is inevitable. Knowing how to efficiently debug your code can save you time and frustration. Two of the most powerful debugging tools in Python are pdb (Python Debugger) and PyCharm’s built-in debugger.

In this guide, we’ll explore how to debug Python like a pro using pdb and PyCharm’s debugger. You’ll learn step-by-step how to set breakpoints, inspect variables, and fix errors efficiently.(Python Debugging Like a Pro)

🔗Related Posts:

What is Debugging?
Why Use pdb and PyCharm’s Debugger?
Getting Started with pdb
Common pdb Commands and Their Uses
PyCharm’s Debugger: A Powerful Alternative
Step-by-Step Guide to Debugging in PyCharm
Best Practices for Efficient Debugging
Conclusion
Frequently Asked Questions (FAQs) for Python Debugging Like a Pro

What is Debugging?

Debugging is the process of identifying, analyzing, and fixing errors in a program. Bugs can cause incorrect outputs, crashes, or performance issues. Debugging tools help developers track down these issues efficiently.

Why Use `pdb` and PyCharm’s Debugger?

Python offers several debugging tools, but pdb and PyCharm’s debugger stand out due to their efficiency and ease of use.

✅ pdb (Python Debugger)

A built-in debugging tool available in all Python installations.
Works directly in the terminal without requiring an external tool.
Lightweight and easy to use.

✅ PyCharm’s Debugger

A feature-rich, visual debugger integrated into PyCharm.
Provides a GUI with breakpoints, step execution, and variable inspection.
Saves time by making debugging intuitive and user-friendly.

Both tools are essential for any developer looking to debug Python code effectively.

Getting Started with `pdb`

pdb is Python’s built-in debugging module. You don’t need to install anything extra—just import and use it.

Basic Usage

To start using pdb, insert the following line in your script where you want to pause execution:

When the code reaches this line, execution will pause, allowing you to inspect variables and step through the code.

Example

def divide(a, b):
import pdb; pdb.set_trace() # Debugging starts here
result = a / b
return resultprint(divide(10, 2))

Run the script, and when it reaches pdb.set_trace(), the debugger will activate.

Common `pdb` Commands and Their Uses

Python Debugging Like a Pro Command Description
n Execute the next line of code
s Step into a function call
c Continue execution until the next breakpoint
q Quit the debugger
p var Print the value of var
l List the surrounding code
h Get help on available commands

Using these commands, you can effectively navigate through your code and identify errors.

PyCharm’s Debugger: A Powerful Alternative

PyCharm, one of the most popular Python IDEs, includes a built-in debugger that offers a more user-friendly debugging experience.

Why Use PyCharm’s Debugger?

No need to insert pdb.set_trace() manually.
Graphical interface for setting breakpoints.
Step-by-step execution for better debugging insights.
Variable inspection, watches, and expression evaluation.

Step-by-Step Guide to Debugging in PyCharm

Step 1: Set a Breakpoint

Open your Python script in PyCharm.
Click on the left margin next to the line number where you want execution to pause. A red dot will appear, indicating a breakpoint.

Step 2: Start Debugging

Click Run > Debug or press Shift + F9 to start debugging.

Step 3: Control Execution

Use the following controls in PyCharm’s debugger:
✅ Step Over (F8): Executes the next line without stepping into functions.
✅ Step Into (F7): Moves inside function calls for deeper debugging.
✅ Resume Program (F9): Continues execution until the next breakpoint.

Step 4: Inspect Variables

Use the Variables panel to check variable values.
Modify values during runtime to test different scenarios.

Step 5: Use Watches & Evaluate Expressions

Add variables to Watches to track changes in their values.
Use the Evaluate Expression tool (Alt + F8) to test expressions dynamically.

Best Practices for Efficient Debugging

1. Use Breakpoints Wisely

Don’t add too many breakpoints. Focus on critical areas where the bug is likely occurring.

2. Print Statements vs. Debugger

While print() can help, a debugger provides a more powerful way to inspect variables and flow.

3. Debug in Small Increments

Run your code in smaller sections to isolate issues quickly.

4. Read Error Messages Carefully

Python’s traceback messages provide valuable insights into what went wrong.

5. Use Logging for Advanced Debugging

If debugging in production, consider using Python’s logging module for tracking issues.

import logginglogging.basicConfig(level=logging.DEBUG)
logging.debug("This is a debug message")

For more details, check out Python’s official pdb documentation and PyCharm Debugging Guide.

Conclusion

Debugging is a vital skill for any Python developer. Whether you prefer pdb for its simplicity or PyCharm’s debugger for its GUI-based ease of use, mastering these tools will make your debugging process faster and more efficient.

By following the best practices outlined in this guide, you can Python Debugging Like a Pro and ensure your code runs smoothly with minimal errors.

📌 Frequently Asked Questions (FAQs) for Python Debugging Like a Pro

1. What is the best way to debug Python code?

The best way to debug Python code depends on your preference. Using pdb (Python Debugger) is a lightweight, built-in method, while PyCharm’s Debugger offers a graphical interface with advanced features like breakpoints, variable inspection, and step execution.

2. How do I start debugging with `pdb`?

You can start debugging with pdb by adding this line in your code:
import pdb; pdb.set_trace()
When you run the script, execution will pause at that line, allowing you to inspect variables and control execution using commands like n (next), s (step into), and c (continue).

3. What are the benefits of using PyCharm’s Debugger?

PyCharm’s debugger provides:
✅ A user-friendly graphical interface.
✅ Easy breakpoints and step-by-step execution.
✅ Real-time variable inspection.
✅ Faster debugging compared to manual pdb usage.

4. Can I debug without using an external tool?

Yes! Python’s built-in print() statements and logging module can help identify issues. However, pdb and PyCharm’s debugger provide more efficient debugging capabilities, reducing the need for excessive print statements.

5. How do I set breakpoints in PyCharm?

To set a breakpoint in PyCharm:
-Click on the left margin next to the line number in your code.
-A red dot will appear, marking the breakpoint.
-Run the script in Debug Mode (Shift + F9) to pause execution at the breakpoint.

7. Is debugging in PyCharm free?

Yes! PyCharm’s debugger is available in both the free (Community) and paid (Professional) versions. However, the Professional version includes extra features for advanced debugging, like remote debugging and profiling.

8. Can I debug Python scripts in VS Code?

Yes! VS Code’s built-in debugger also supports Python debugging with breakpoints, step execution, and variable inspection. You need to install the Python extension for full debugging features.

9. What’s the difference between debugging and testing?

–Debugging: The process of identifying and fixing errors in code.
–Testing: Running tests (e.g., unit tests) to check if the code behaves correctly. Debugging is used after finding a bug, while testing helps prevent bugs from occurring.

10. How can I improve my debugging skills?

To become a pro at debugging, follow these best practices:
🔹 Use breakpoints to pause execution at critical points.
🔹 Use pdb or PyCharm’s debugger instead of excessive print() statements.
🔹 Read Python’s error messages carefully—they often pinpoint the issue.
🔹 Debug in small sections instead of running the entire script at once.
🔹 Use logging for better tracking of runtime issues.

Do you have a favorite debugging technique? Share it in the comments below!

Author

Ravi Prajatpat's
Ravi Prajapati is a BCA graduate with 4 years of experience in the IT field. Currently working as a Desktop Support Engineer in a private company in Noida, Ravi has strong technical knowledge and expertise in troubleshooting and support.
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Python Debugging Like a Pro: Using pdb and PyCharm Debugger

Introduction

Table of Contents

What is Debugging?

Why Use `pdb` and PyCharm’s Debugger?