How can I put an actual backslash in a string literal (not use it for an escape sequence)?

Question

I have this code:

import os
path = os.getcwd()
final = path +'xulrunner.exe ' + path + 'application.ini'
print(final)

I want output like:

C:Usersmexulrunner.exe C:Usersmeapplication.ini

But instead I get an error that looks like:

SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 0-1: truncated xXX escape

I don’t want the backslashes to be interpreted as escape sequences, but as literal backslashes. How can I do it?

_{Note that if the string should only contain a backslash – more generally, should have an odd number of backslashes at the end – then raw strings cannot be used. Please use How can I get a string with a single backslash in it? to close questions that are asking for a string with just a backslash in it. Use How to write string literals in python without having to escape them? when the question is specifically about wanting to avoid the need for escape sequences.}

Asked By: esafwan

||

Source

Answer 1

To answer your question directly, put r in front of the string.

final= path + r'xulrunner.exe ' + path + r'application.ini'

But a better solution would be os.path.join:

final = os.path.join(path, 'xulrunner.exe') + ' ' + 
         os.path.join(path, 'application.ini')

(the backslash there is escaping a newline, but you could put the whole thing on one line if you want)

I will mention that you can use forward slashes in file paths, and Python will automatically convert them to the correct separator (backslash on Windows) as necessary. So

final = path + '/xulrunner.exe ' + path + '/application.ini'

should work. But it’s still preferable to use os.path.join because that makes it clear what you’re trying to do.

Answered By: David Z

Answer 2

You can escape the slash. Use \ and you get just one slash.

Answered By: avacariu

Answer 3

You can escape the backslash with another backslash (\), but it won’t look nicer. To solve that, put an r in front of the string to signal a raw string. A raw string will ignore all escape sequences, treating backslashes as literal text. It cannot contain the closing quote unless it is preceded by a backslash (which will be included in the string), and it cannot end with a single backslash (or odd number of backslashes).

Answered By: Einsteinium

Answer 4

Another simple (and arguably more readable) approach is using string raw format and replacements like so:

import os
path = os.getcwd()
final = r"{0}xulrunner.exe {0}application.ini".format(path)
print(final)

or using the os path method (and a microfunction for readability):

import os

def add_cwd(path):
    return os.path.join( os.getcwd(), path )

xulrunner = add_cwd("xulrunner.exe")
inifile = add_cwd("application.ini")
# in production you would use xulrunner+" "+inifile
# but the purpose of this example is to show a version where you could use any character
# including backslash
final = r"{} {}".format( xulrunner, inifile )
print(final)

Answered By: Chris Rudd

How can I put an actual backslash in a string literal (not use it for an escape sequence)?

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