debugging
Debugging is the process of identifying, analyzing, and removing errors or bugs from your code. As a programmer, you’ll often find yourself debugging code to ensure that it runs smoothly and produces the expected results. Debugging is a crucial part of software development and helps maintain the quality and reliability of your code.
In Python, you have several tools and techniques for effective debugging, such as the print() function and the pdb module. You can also use an integrated development environment (IDE) with built-in debugging support.
Example
Here’s an example of debugging a Python script using the built-in print() function:
>>> def find_max(numbers):
... max_value = 0 # Potential bug if all values are negative
... print(f"Initial max_value: {max_value}")
... for num in numbers:
... print(f"Checking number: {num}")
... if num > max_value:
... max_value = num
... print(f"Updated max_value: {max_value}")
... return max_value
...
>>> numbers = [-5, -10, -3, -8]
>>> print(f"Max value: {find_max(numbers)}")
Initial max_value: 0
Checking number: -5
Checking number: -10
Checking number: -3
Checking number: -8
Max value: 0
In this example, the initial value of max_value is 0, which is greater than all numbers in the list. As a result, max_value is never updated. The calls to print(), especially the first one, help you decipher the bug. The other calls give you additional information to fix the error.
To remove this bug from your code, you can do max_value = numbers[0]. This assignment initializes the sentinel variable with a value from the list, preventing the issue.
Related Resources
Tutorial
Python Debugging With Pdb
In this hands-on tutorial, you'll learn the basics of using pdb, Python's interactive source code debugger. Pdb is a great tool for tracking down hard-to-find bugs and allows you to fix faulty code more quickly.
For additional information on related topics, take a look at the following resources:
By Leodanis Pozo Ramos • Updated May 12, 2025