What Are the Best Debugging Techniques in Python?

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Debugging is an essential skill for any Python developer. Whether you’re a beginner or an experienced coder, errors are inevitable. But don’t worry—debugging is a skill you can master with the right techniques! Knowing how to find and fix issues efficiently can save you hours of frustration and make your code more reliable. In this blog, we’ll explore the best debugging techniques in Python and how you can apply them to your projects.

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1. Print Statements: The Classic Debugging Tool

One of the simplest ways to debug your Python code is by using print statements. By printing values at different points in your code, you can track how variables change and identify where things go wrong.

Example:

x = 10

y = 0

print(“Before division”)

print(“x:”, x, “y:”, y)

result = x / y  # This will cause a ZeroDivisionError

print(“Result:”, result)

The print statements before the error help you see what values are being used.

However, excessive print statements can clutter your code. That’s where logging comes in.

2. Using Logging Instead of Print

Python’s built-in logging module is a better alternative to print statements. It allows you to track different levels of messages (info, warning, error, etc.) and enables easy debugging.

Example:

import logging

logging.basicConfig(level=logging.DEBUG)

logger = logging.getLogger()

x, y = 10, 0

logger.debug(“Before division: x=%d, y=%d”, x, y)

try:

    result = x / y

except ZeroDivisionError:

    logger.error(“Division by zero error”, exc_info=True)

Using logging makes debugging easier, especially in larger applications.

3. Debugging with Python’s Built-in Debugger (pdb)

Python provides a built-in debugger called pdb, which lets you step through code execution interactively.

Example:

import pdb

def divide(a, b):

    pdb.set_trace()  # Debugging breakpoint

    return a / b

result = divide(10, 0)

When you run this script, it will pause at set_trace(), allowing you to inspect variables and step through the execution.

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4. Using Exception Handling for Debugging

Handling exceptions properly can prevent your program from crashing and help you identify the root cause of issues.

Example:

try:

    x, y = 10, 0

    result = x / y

except ZeroDivisionError as e:

    print(“Error:”, e)

Instead of letting the program crash, this approach gracefully handles errors and provides useful information.

5. Debugging with IDE Debugging Tools

Most modern IDEs like PyCharm, VS Code, and Jupyter Notebook come with built-in debugging tools. Features like breakpoints, variable inspection, and step-through execution make debugging much easier.

For example, in PyCharm:

  • Click on the left margin to set breakpoints.
  • Run the script in debug mode.
  • Step through the code and inspect variables dynamically.

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6. Using Assert Statements for Debugging

Assertions help you validate assumptions in your code and catch errors early.

Example:

def get_positive_number(num):

    assert num > 0, “Number must be positive”

    return num

print(get_positive_number(-5))  # This will raise an AssertionError

Assertions are useful during development but should be removed in production.

7. Profiling and Performance Debugging

If your Python program is slow, debugging performance issues is crucial. The cProfile module helps analyze execution time.

Example:

import cProfile

def slow_function():

    total = 0

    for i in range(10**6):

        total += i

    return total

cProfile.run(‘slow_function()’)

This will show a detailed report on execution time for different parts of the function.

8. Debugging Memory Issues with tracemalloc

Memory leaks can be tricky to debug. The tracemalloc module helps track memory usage.

Example:

import tracemalloc

tracemalloc.start()

x = [i for i in range(100000)]

print(tracemalloc.get_traced_memory())

tracemalloc.stop()

This helps identify which parts of the code consume the most memory.

Debugging is an art that every Python developer should master. By using print statements, logging, pdb, exception handling, and IDE debugging tools, you can efficiently find and fix errors in your code. If you’re working on automation testing, mastering debugging techniques through a Selenium Training in Bangalore will be highly beneficial. Whether you’re building applications or testing software, effective debugging ensures smooth performance and fewer headaches!