python replace single backslash with double backslash

Question

In python, I am trying to replace a single backslash ("\") with a double backslash("\"). I have the following code:

directory = string.replace("C:\Users\Josh\Desktop\20130216", "\", "\\") 

However, this gives an error message saying it doesn't like the double backslash. Can anyone help?

Answer 1

No need to use str.replace or string.replace here, just convert that string to a raw string:

>>> strs = r"C:\Users\Josh\Desktop\20130216"            ^            |        notice the 'r' 

Below is the repr version of the above string, that's why you're seeing \\ here. But, in fact the actual string contains just '\' not \\.

>>> strs 'C:\\Users\\Josh\\Desktop\\20130216'  >>> s = r"f\o" >>> s            #repr representation 'f\\o' >>> len(s)   #length is 3, as there's only one `'\'` 3 

But when you're going to print this string you'll not get '\\' in the output.

>>> print strs C:\Users\Josh\Desktop\20130216 

If you want the string to show '\\' during print then use str.replace:

>>> new_strs = strs.replace('\\','\\\\') >>> print new_strs C:\\Users\\Josh\\Desktop\\20130216 

repr version will now show \\\\:

>>> new_strs 'C:\\\\Users\\\\Josh\\\\Desktop\\\\20130216' 

Answer 2

Let me make it simple and clear. Lets use the re module in python to escape the special characters.

Python script :

import re s = "C:\Users\Josh\Desktop" print s print re.escape(s) 

Output :

C:\Users\Josh\Desktop C:\\Users\\Josh\\Desktop 

Explanation :

Now observe that re.escape function on escaping the special chars in the given string we able to add an other backslash before each backslash, and finally the output results in a double backslash, the desired output.

Hope this helps you.