Quoting backslashes in Python string literals

Chris_Bunch_422 0
Viewed 238829

I have a string that contains both double-quotes and backslashes that I want to set to a variable in Python. However, whenever I try to set it, the quotes or slashes are either removed or escaped. Here's an example:

>>> foo = 'baz "\"'
>>> foo
'baz ""'

So instead of baz "\" like I want I'm getting baz "". If I then try to escape the backslash, it doesn't help either:

>>> foo = 'baz "\\"'
>>> foo
'baz "\\"'

Which now matches what I put in but wasn't what I originally wanted. How do you get around this problem?

python string
5 Answers

You're being mislead by output -- the second approach you're taking actually does what you want, you just aren't believing it. :)

>>> foo = 'baz "\\"'
>>> foo
'baz "\\"'
>>> print(foo)
baz "\"

Incidentally, there's another string form which might be a bit clearer:

>>> print(r'baz "\"')
baz "\"
user_141220

Use a raw string:

>>> foo = r'baz "\"'
>>> foo
'baz "\\"'

Note that although it looks wrong, it's actually right. There is only one backslash in the string foo.

This happens because when you just type foo at the prompt, python displays the result of __repr__() on the string. This leads to the following (notice only one backslash and no quotes around the printed string):

>>> foo = r'baz "\"'
>>> foo
'baz "\\"'
>>> print(foo)
baz "\"

And let's keep going because there's more backslash tricks. If you want to have a backslash at the end of the string and use the method above you'll come across a problem:

>>> foo = r'baz \'
  File "<stdin>", line 1
    foo = r'baz \'
                 ^  
SyntaxError: EOL while scanning single-quoted string

Raw strings don't work properly when you do that. You have to use a regular string and escape your backslashes:

>>> foo = 'baz \\'
>>> print(foo)
baz \

However, if you're working with Windows file names, you're in for some pain. What you want to do is use forward slashes and the os.path.normpath() function:

myfile = os.path.normpath('c:/folder/subfolder/file.txt')
open(myfile)

This will save a lot of escaping and hair-tearing. This page was handy when going through this a while ago.

Harley_10570

What Harley said, except the last point - it's not actually necessary to change the '/'s into '\'s before calling open. Windows is quite happy to accept paths with forward slashes.

infile = open('c:/folder/subfolder/file.txt')

The only time you're likely to need the string normpathed is if you're passing to to another program via the shell (using os.system or the subprocess module).

user_388510

If you are here for a filepath just use "\\"

import os
path = r"c:\file"+"\\"+"path"
os.path.normpath(path)

which will outputc:\file\path

user_134571230
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