Error Handling in Python: Using Try-Except Blocks

In our everyday life, we often plan for unexpected situations: carrying an umbrella in case it rains or saving a document repeatedly to avoid data loss.

Similarly, in the programming world, unexpected events or errors can occur, which can disrupt the flow of our program. That’s where error handling comes into play, ensuring our program can handle unexpected situations gracefully.

In Python, the most straightforward mechanism for error handling is using the try–except blocks. This guide simplifies the concept for busy individuals or even a tenth grader who’s eager to grasp the basics.

Why is Error Handling Necessary?

Before diving in, let’s understand why we even bother about errors. When a Python script encounters a situation it cannot cope with, it raises an exception. An unhandled exception causes the program to stop running.

Through error handling, we can provide our script the instructions on what to do when it encounters these issues, allowing it to continue running or fail gracefully, giving the user a friendly notification.

The Basics: Try and Except

Think of the try block as performing an action that might have issues. The except block contains the backup plan if things go south in the try block.

# How to use the try and except block
try:
    # Code that might cause an error
    result = 10 / 0
except:
    print("Oops! Something went wrong.")

In the code above, we’re trying to divide by zero, which isn’t allowed in mathematics. So, Python will skip to the except block and print out “Oops! Something went wrong.”

Being Specific with Errors

It’s good to know that an error occurred, but better to know what kind of error it was.

# Giving specific error messages
try:
    result = 10 / 0
except ZeroDivisionError:
    print("You can't divide by zero!")

Here, ZeroDivisionError is a specific type of error Python recognizes. By naming it, our except block will only catch this specific error.

Multiple Except Blocks

We can have multiple except blocks for different types of errors:

try:
    # This could result in a ZeroDivisionError or a TypeError
    num = "five"
    result = 10 / num
except ZeroDivisionError:
    print("You can't divide by zero!")
except TypeError:
    print("Please use numbers only!")

Using the Else and Finally Clauses

• Else: Runs when the try block does not raise any errors.

try:
    result = 10 / 2
except ZeroDivisionError:
    print("You can't divide by zero!")
else:
    print(f"The result is {result}")

Finally: Always runs, whether there was an error or not. Useful for cleanup actions, like closing a file.

try:
    result = 10 / 2
except ZeroDivisionError:
    print("You can't divide by zero!")
finally:
    print("This will print no matter what.")

Conclusion

Error handling with try–except blocks in Python empowers us to anticipate potential pitfalls in our code and manage them proactively. By understanding and implementing these, not only does our code become more robust, but it also offers a more user-friendly experience.

For further insights into Python basics or diving deeper into advanced topics, explore our recently published blog posts. And as always, if you find value in our content, don’t forget to comment or follow us on Twitter!