Reference library

Errors & debugging

Handle failures gracefully and write clearer error messages for future you.

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Errors & debugging easy

Try/except ValueError

Convert user input to int inside try/except and show a friendly message.

errors try-except input

Python

raw = "42"

try:
    value = int(raw)
    print(f"Parsed: {value}")
except ValueError:
    print(f"Could not parse {raw!r} as an integer.")

3 0 Open

Errors & debugging medium

Raise a clear custom error

Validate input early and raise ValueError with a helpful message.

errors raise validation

Python

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)

3 1 Open

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Each section groups closely related Python snippets.

Strings & text 3 Lists & loops 3 Functions & basics 2 Files & data 2 Errors & debugging 2