Exception Handling Guide

Introduction

Exception handling is a critical aspect of robust Python programming. It allows developers to manage errors gracefully and ensure the stability of their applications. 🛡️

When an error occurs during program execution, Python raises an exception. Proper handling prevents crashes and provides meaningful feedback to users. Always remember to handle exceptions that you expect, and avoid catching generic exceptions like Exception unless necessary. 🚨

Basic Structure

Here's the fundamental syntax for exception handling in Python:

try:
    # Code that may raise an exception
except ExceptionType:
    # Code to handle the exception
else:
    # Code to execute if no exception is raised
finally:
    # Code to execute regardless of exceptions

• try: Contains the code that might trigger an exception.
• except: Specifies the type of exception to catch and handles it.
• else: Executes when no exceptions are raised.
• finally: Runs no matter what, useful for cleanup tasks.

Common Exception Types

Python has a wide range of built-in exceptions. Some commonly encountered ones include:

• ValueError: Raised when a function receives an argument of correct type but inappropriate value.
• KeyError: Occurs when a key is not found in a dictionary.
• IOError: Happens when an I/O operation (e.g., file reading/writing) fails.
• ZeroDivisionError: Triggered when dividing by zero.

For example, handling a ValueError:

try:
    num = int(input("Enter a number: "))
except ValueError:
    print("Invalid input! Please enter a valid integer.")

Best Practices

1. Be specific with exceptions: Catch only the exceptions you expect.
2. Use finally for cleanup: Ensure resources are released even if an exception occurs.
3. Log errors: Use logging instead of print statements for production code. 📝
4. Avoid bare except blocks: Never catch all exceptions unless you have a specific reason.

Expand Reading

For more information, check our Python Exception Handling Documentation. 📚