Python change directory returns strange error

Question

I think it's a basic python problem, but I just can't find out why.

I have a file named tc_500 containing some CSV files I want to edit, thus I change the directory in order to edit these files.

import sys, os
os.chdir('C:\Users\Heinz\Desktop\tc_500')
print os.getcwd()

But it turns out this error,

>>> 

Traceback (most recent call last):
  File "C:\Users\Heinz\Desktop\python_test\any_test.py", line 13, in <module>
    os.chdir('C:\Users\Heinz\Desktop\tc_500')
WindowsError: [Error 123] 檔案名稱、目錄名稱或磁碟區標籤語法錯誤。: 'C:\\Users\\Heinz\\Desktop\tc_500'

If I change the code like this,

import sys, os
os.chdir('C:\Users\Heinz\Desktop\TC_500')
print os.getcwd()

It can run without any error.

Why I wouldn't get errors while using capitals instead of the real name of the file？

MattDMo · Accepted Answer · 2014-04-30 18:46:00Z

5

You need to use double back slashes in your path:

os.chdir('C:\\Users\\Heinz\\Desktop\\tc_500')

or single forward slashes:

os.chdir('C:/Users/Heinz/Desktop/tc_500')

The sequence \t is an escape sequence for a tab character, and that is messing up further processing of the string. \T is not an escape sequence. The first back slash escapes the second back slash, allowing for the correct path to be passed.

answered Apr 30, 2014 at 18:46

MattDMo

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5 Comments

Garrett Hyde Over a year ago

You can also use raw strings (e.g., r'C:\Users\Heinz\Desktop\tc_500').

MattDMo Over a year ago

@Heinz - as I said in my answer, \t is an escape sequence, but \T is not. In the first instance, the literal string you're passing is 'C:\Users\Heinz\Desktop c_500', in the second case it's 'C:\Users\Heinz\Desktop\TC_500'. In nearly all situations (unless you're using a case-sensitive NTFS volume) Windows paths are case-insensitive.

Heinz Over a year ago

@MattDMo but there are no capitals in my file name, I think in the second case, python may not find my file either.

MattDMo Over a year ago

@Heinz - you already said in your question that the second case worked, which it should. If your current working directory was C:\Users\Heinz\Desktop, and you entered either os.chdir('tc_500') or os.chdir('Tc_500') or os.chdir('tC_500') or os.chdir('TC_500'), all would work, because Windows ignores case in file/directory names.

MattDMo Over a year ago

@Heinz - When you have an escape character in a non-raw string, Python strips the escape sequence out and inserts the literal ASCII value of that sequence in the string before passing it to Windows, and of course Windows doesn't interpret it correctly.

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