[Solved] getting ZeroDivisionError: integer division or modulo by zero

Question

Your factorial() function returns 0 for any input because of how you defined your range.

The range builtin starts at 0 unless otherwise defined so:

for c in range(n):
    re = re * c  # no semicolons in Python

is doing:

re = re * 0

on the first iteration so for all subsequent iterations:

re = 0 * c

will always be 0

Start your range at 1 like so

for c in range(1, n):
    re *= c  # The *= operator is short hand for a = a * b

you can see this more explicityly:

>>> print(list(range(5)))
[0, 1, 2, 3, 4]
>>> print(list(range(1,5)))
[1, 2, 3, 4]
>>>

or instead of rolling your own function use the one that comes with Python:

>>> from math import factorial
>>> factorial(3)
6

Upon closer reading of your code it seems you tried to circumvent this by setting c = 1 outside your for loop. This is not going to work because the variables you declared outside the loop are being reassigned inside it.

Accepted Answer