Reference library
Errors & debugging
Handle failures gracefully and write clearer error messages for future you.
Try/except ValueError
Convert user input to int inside try/except and show a friendly message.
raw = "42"
try:
value = int(raw)
print(f"Parsed: {value}")
except ValueError:
print(f"Could not parse {raw!r} as an integer.")Raise a clear custom error
Validate input early and raise ValueError with a helpful message.
def positive_only(n):
"""Return n if it is strictly positive."""
if n <= 0:
raise ValueError(f"Expected a positive number, got {n}")
return n
print(positive_only(5))
try:
positive_only(-1)
except ValueError as exc:
print(exc)Browse by section
Each section groups closely related Python snippets.
Errors & debugging — Python code examples
What you will find here
This page collects errors & debugging snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.