Python Basics · Error Handling · Lesson 21 of 36
Raising Your Own Exceptions
Concept
Raising Your Own Exceptions
The raise keyword lets your own functions signal a problem, using a built-in exception type like ValueError or a custom message.
Raising stops the function immediately, the same way return does, but signals failure instead of a normal result.
- Explain the core idea behind Raising Your Own Exceptions.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
Self-check before continuing
Without looking at the example, describe what changes when you modify one input in Raising Your Own Exceptions. Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Write a function divide(a, b) that raises a ValueError when b is 0, then call it inside a try/except.
Ask about this lesson or your next move. The guide explains the path without taking the work away from you.
Ready for the next lesson?
Mark this lesson complete when you have finished the exercise.
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