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Debugging is an essential part of software development, and Python’s built-in PDB (Python Debugger) is a powerful tool for this task. In this post, we'll cover how to use PDB to inspect your code and fix bugs.

What is PDB?

PDB is a debugger that allows you to pause your Python program, inspect variables, and step through code interactively. It’s part of Python’s standard library, so no installation is needed.

Setting Up PDB

To use PDB, simply import it and set a breakpoint using pdb.set_trace(). Here's an example:

import pdb

def divide(a, b):
    pdb.set_trace()  # Breakpoint
    return a / b

result = divide(10, 2)
print(result)

When the program reaches pdb.set_trace(), it will pause and give you control in the debugger.

Basic Commands

While in PDB, you can use commands to control the flow of execution:

• n: Execute the next line of code.
• s: Step into a function call.
• c: Continue execution until the next breakpoint.
• p <variable>: Print the value of a variable.
• q: Quit the debugger and stop the program.

Example:

(Pdb) p a  # Print value of 'a'
(Pdb) n    # Execute next line
(Pdb) c    # Continue execution
(Pdb) q    # Quit the debugger

Conclusion

PDB is a simple yet powerful tool to help debug your Python code. By setting breakpoints, inspecting variables, stepping through code, and quitting the debugger when done, you can easily identify and fix issues. Happy debugging!