Error on import: SyntaxError: source code string cannot contain null bytes

[kirkwilliams2049]

I am following a Python tutorial and have created the following module(from the tutorial) in Notepad under Windows 11:

def fib(n):    # write Fibonacci series up to n
    a, b = 0, 1
    while a < n:
        print(a, end=' ')
        a, b = b, a+b
    print()

def fib2(n):   # return Fibonacci series up to n
    result = []
    a, b = 0, 1
    while a < n:
        result.append(a)
        a, b = b, a+b
    return result

I have saved the module as fibo.py. When I attempt to import the module(import fibo), Python returns the error:

Error:
SyntaxError: source code string cannot contain null bytes

Now when I save the module as kw.py or kirk.py, the import works and calls to the functions in the module also work.

What am I missing here?

Gribouillis write Aug-01-2023, 03:54 PM:
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[DPaul]

Make sure your python program has a different filename than the module you are importing.
Paul

[deanhystad]

As Paul says, a file named fibo.py cannot "import fibo". Are you doing that? That would match the name change behaivior (changing name of fibo.py fixes problem), but I would not expect it to report as a syntax error. Instead you should get an AttributeError and there might be some mention of a circular import. I don't think you are telling us everything.

[kirkwilliams2049]

Okay in the interest of full disclosure my Python session looks like this:

Python 3.11.4 (tags/v3.11.4:d2340ef, Jun  7 2023, 05:45:37) [MSC v.1934 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.path.append("C:\\Users\\kirkw\\Documents\\Python")
>>> sys.path
['', 'C:\\Users\\kirkw\\AppData\\Local\\Programs\\Python\\Python311\\python311.zip', 'C:\\Users\\kirkw\\AppData\\Local\\Programs\\Python\\Python311\\DLLs', 'C:\\Users\\kirkw\\AppData\\Local\\Programs\\Python\\Python311\\Lib', 'C:\\Users\\kirkw\\AppData\\Local\\Programs\\Python\\Python311', 'C:\\Users\\kirkw\\AppData\\Local\\Programs\\Python\\Python311\\Lib\\site-packages', 'C:\\Users\\kirkw\\Documents\\Python']
>>> import fibo
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
SyntaxError: source code string cannot contain null bytes
>>> import kirk
>>> kirk.fib(1000)
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987
>>>

I previously created the file fibo.py and then saved it as kirk.py. fibo, as indicated in the session notes above, causes the interface to throw the indicated message. This is not stopping me from moving on in my learning process. However, nuisances like this have a tendency to bite you later on when building production code.

TIA

Larz60+ write Aug-01-2023, 10:40 PM:
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[deanhystad]

Try renaming it fibo.py. I think the file only looks like it is named fibo.py. I almost never use notepad, so I don't know how you gave the file a bad name, but it looks like you somehow managed to imbed null characters in a string. Probably some unicode encoding/decoding oddity.

[Gribouillis]

Try this

>>> from importlib.util import find_spec
>>> spec = find_spec('fibo')
>>> print(spec)

[kirkwilliams2049]

Try this

>>> from importlib.util import find_spec
>>> spec = find_spec('fibo')
>>> print(spec)

Thanks very much. I had created the module using Word earlier and placed it in the path:
ModuleSpec(name='fibo', loader=<_frozen_importlib_external.SourceFileLoader object at 0x000002A2CA059D10>, origin='C:\\Users\\kirkw\\AppData\\Local\\Programs\\Python\\Python311\\fibo.py'). Of course I forgot about that. It has been a few years since I have done any serious coding other that sql scripts and I am making all kinds of rooky mistakes - duh.

[Gribouillis]

I am making all kinds of rooky mistakes

The folder C:\\Users\\kirkw\\AppData\\Local\\Programs\\Python\\Python311 is certainly not the place to store your own programs! Move them away from here.