pythonType errorEasy

Counting digits crashes on a number

Time: 0:00

BugFind the bug and fix the code

What it should do

count_digits(n) returns how many digits a positive whole number has. Example: count_digits(12345) → 5.

What happens instead

count_digits(12345) crashes: TypeError: object of type 'int' has no len().

def count_digits(n):
    return len(n)

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

⏱️0:00

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Hint 2

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Hint 3

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This bug belongs to the type errors pattern

Totals that concatenate, sorts that put 10 before 9, comparisons that refuse to run.

Learn the type errors pattern Step through your own code

Spoiler: why this bug happens(try it first; the hints get warmer one at a time)

What went wrong: a number has no length. len() only works on things with items, like text or lists.

The fix: return len(str(n))

Remember: to count digits, turn the number into text first.

The pattern behind it: type errors.

More type errors to practise

Seen this error in your own code?

TypeError: object of type 'int' has no len()

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