There is a file named "µTorrent.lnk" in the folder.

Here is the code:

#encoding=utf-8

import os
for i in os.listdir('.'):
    print os.path.isfile(i), '\t', i
a = input()

and the output:


True    3.py
False   aμ汉字.txt
True    uTorrent.lnk
False   μTorrent.lnk
False   μTorrent1.lnk
False   μ汉字.txt
False   μ汉字.txt.lnk
True    αγβδο
True    φχ.txt
True    φχ.txt.lnk


the function just doesn't work with the character "μ"

I am unable to reproduce this on any python from py3k trunk down to 2.6.6.  Can you provide a complete test program that demonstrates the failure?  (That is, it creates the file and then fails to detect it as a file with isfile.)

Oh, yes, and it is likely to be important to know what OS you are on.  I tested on linux.

I encoutered this problem on Winxp sp3.

I have retested it on the win7, and it could return the correct value as it did on linux.

Since the os functions tend to be small wrappers around system functions, this sounds like it is probably a platform issue and not a Python issue.  I'm adding our windows experts as nosy, they can reopen the issue if they disagree.

Just a random thought (no, I don't know anything about Windows): there are two "mu" characters: GREEK SMALL LETTER MU (μ) and MICRO SIGN (µ).  Normalization turns one into the other:

>>> from unicodedata import *
>>> name(normalize('NFKC', '\N{MICRO SIGN}'))
'GREEK SMALL LETTER MU'

it is possible that somehow the two characters get confused by OP system.

I could not reproduce the issue on OSX, so I won't reopen it.

On Windows, using the bytes APIs for filenames is unreliable and fails for characters that are not in the ANSI code page. So you should use

import os
for i in os.listdir(u'.'):
    print os.path.isfile(i), '\t', i

instead.