Python Try...Except 🛡️

Handling Errors Gracefully

Exception handling allows you to manage runtime errors without crashing your program. Use try, except, else, and finally blocks.

🎈 Analogy: The Airbag

Think of a try...except block as an Airbag in a car.
- Normal Driving (Try): You drive along, hoping nothing happens.
- Crash (Exception): If you hit something, the airbag deploys (Except block runs) to save you.
- Without it, the car (program) would be totally destroyed (crash).

✨ Basic Structure

python

try:
    # Code that might raise an exception
    print(x)
except NameError:
    # Handle specific error
    print("Variable x is not defined")
except Exception as e:
    # Handle any other error
    print(f"An error occurred: {e}")
else:
    # Runs if NO exception occurs
    print("Success!")
finally:
    # Always runs (cleanup)
    print("Finished")

🎯 Real-World Application: Network Requests

When fetching data from the internet, things often go wrong (offline, server down). You must handle this gracefully.

python

import requests

try:
    response = requests.get("https://api.example.com/data")
    response.raise_for_status() # Check for HTTP errors
    print(response.json())
except requests.exceptions.ConnectionError:
    print("⚠️ No internet connection!")
except requests.exceptions.Timeout:
    print("⚠️ Request timed out!")
except Exception as e:
    print(f"⚠️ Something went wrong: {e}")

🚀 Raising Exceptions

You can manually trigger exceptions using the raise keyword. This is useful for enforcing constraints.

python

x = -1

if x < 0:
    raise ValueError("Sorry, no numbers below zero")

🛠️ Custom Exceptions

You can create your own exception classes by inheriting from the built-in Exception class.

python

class InvalidAgeError(Exception):
    pass

age = 150
if age > 120:
    raise InvalidAgeError("Age is too high!")

⚠️ Watch Out!

Avoid using a bare except: clause. It catches ALL exceptions, including system exit signals (like Ctrl+C), which can make it hard to stop your program. Always specify the exception type or use except Exception:.