python: IndentationError: unindent does not match any outer indentation level

Question

When I compile the code below, I get

IndentationError: unindent does not match any outer indentation level

import sys

def Factorial(n): # return factorial
    result = 0
    for i in range (1,n):
        result = result * i
    print "factorial is ",result
    return result

Any ideas why?

Answer 1

EDIT: Other posters are probably correct...there might be spaces mixed in with your tabs. Try doing a search&replace to replace all tabs with a few spaces.

Try this:

import sys

def Factorial(n): # return factorial
    result = 1
    for i in range (1,n):
        result = result * i
    print "factorial is ",result
    return result

print Factorial(10)

Answer 2

The line: result = result * i should be indented (it is the body of the for-loop).

Or - you have mixed space and tab characters

Answer 3

Are you sure you are not mixes tabs and spaces in your indentation white space? (That will cause that error.)

Note, it is recommended that you don't use tabs in python code. See the Style Guide. You should configure notepad++ to insert spaces for tabs.

Answer 4

Whenever I've encountered this error, it's because I've somehow mixed up tabs and spaces in my editor.

Answer 5

To easily check for problems with tabs/spaces you can actually do this:

python -m tabnanny yourfile.py

or you can just set up your editor correctly of course :-)