error in os.chdir

Peter J. Holzer hjp-python at
Sun Jul 1 05:42:09 EDT 2018

On 2018-07-01 08:50:22 +0000, Steven D'Aprano wrote:
> On Sun, 01 Jul 2018 03:18:23 +0000, eryk sun wrote:
> > On Sun, Jul 1, 2018 at 1:44 AM, Steven D'Aprano
> > <steve+comp.lang.python at> wrote:
> >> I guess that if the user is using a path beginning with \\?\ they may
> >> or may not need to use backslashes, but I have no way of testing it,
> >> and I would expect that Python will correctly replace //?/ with
> >> backslashes the same as it does for any other file system path.
> > 
> > The Windows API handles this, but not for a path that begins with \\?\.
> But what about the *Python* API? The Python open() function, and all the 
> high-level os.* and os.path.* functions which take paths as strings are 
> supposed to automatically convert forward slashes to backslashes. Aren't 
> they?

Are they? I don't see anything in the docs that support this (but maybe
my Google Fu is weak).

Rather from the existence and design of os.path I conclude that the
programmer is supposed to construct path names in the local convention
(i.e., you should use os.path.join(dirname, filename) instead of dirname +
"/" + filename, which will ensure that the correct separator is used).

I think the lazy approach using just forward slashes works because
*Windows* treats slashes in filenames like backslashes (most of the
time), not because Python converts them.


   _  | Peter J. Holzer    | we build much bigger, better disasters now
|_|_) |                    | because we have much more sophisticated
| |   | hjp at         | management tools.
__/   | | -- Ross Anderson <>
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