Error Handling and Exceptions Python

What You’ll Learn 📚

• Understanding what exceptions are and why they occur
• How to handle exceptions using try-except blocks
• Different types of exceptions and when to use them
• Best practices for error handling in Python

Introduction to Error Handling

Errors are a natural part of programming. They can occur for various reasons, such as invalid input, network issues, or even bugs in the code. In Python, errors are often referred to as exceptions. Understanding how to handle these exceptions gracefully is crucial for writing robust programs.

Key Terminology

• Exception: An error that occurs during the execution of a program.
• Try Block: A block of code that is attempted to be executed.
• Except Block: A block of code that is executed if an exception occurs in the try block.
• Raise: A keyword used to trigger an exception manually.

Simple Example: The Basics of Try-Except

try:
    # Attempt to divide by zero
    result = 10 / 0
except ZeroDivisionError:
    print("Oops! You can't divide by zero.")

Progressively Complex Examples

Example 1: Handling Multiple Exceptions

try:
    # Attempt to open a file and divide by zero
    with open('file.txt', 'r') as file:
        data = file.read()
    result = 10 / 0
except FileNotFoundError:
    print("File not found. Please check the file path.")
except ZeroDivisionError:
    print("Oops! You can't divide by zero.")

Example 2: Using Else and Finally

try:
    result = 10 / 2
except ZeroDivisionError:
    print("Oops! You can't divide by zero.")
else:
    print("Division successful! Result is:", result)
finally:
    print("Execution completed.")

Example 3: Raising Exceptions

def check_age(age):
    if age < 0:
        raise ValueError("Age cannot be negative.")
    print("Age is valid.")

try:
    check_age(-1)
except ValueError as e:
    print("Error:", e)

Common Questions and Answers

1. What is the difference between an error and an exception?

   An error is a broader term that includes any issue in the code, while an exception is a specific type of error that can be caught and handled.

2. Why should I use try-except blocks?

   They allow your program to continue running even when an error occurs, providing a way to handle unexpected situations gracefully.

3. Can I have multiple except blocks?

   Yes, you can have multiple except blocks to handle different types of exceptions separately.

4. What happens if an exception is not caught?

   If an exception is not caught, it will propagate up the call stack and may terminate the program.

5. How can I catch all exceptions?

   You can use a generic except Exception: block, but it's better to catch specific exceptions when possible.

Troubleshooting Common Issues

Be careful not to catch exceptions too broadly, as this can hide bugs and make debugging difficult.

Use specific exceptions to provide more meaningful error messages and handle different error types appropriately.

Remember, practice makes perfect! Don't hesitate to try these examples yourself and experiment with different scenarios. Happy coding! 🚀