Adding backslashes without escaping [Python] [duplicate]

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Adding backslashes without escaping [Python] [duplicate]

I need to escape a & (ampersand) character in a string. The problem is whenever I string = string.replace ('&', '&') the result is '\&'. An extra backslash is added to escape the original backslash. How do I remove this extra backslash?

Answer #1:

The result '\&' is only displayed – actually the string is &:

>>> str = '&'
>>> new_str = str.replace('&', '&')
>>> new_str
'\&'
>>> print new_str
&

Try it in a shell.

Answered By: Emil Ivanov

Answer #2:

The extra backslash is not actually added; it’s just added by the repr() function to indicate that it’s a literal backslash. The Python interpreter uses the repr() function (which calls __repr__() on the object) when the result of an expression needs to be printed:

>>> '\'
'\'
>>> print '\'

>>> print '\'.__repr__()
'\'
Answered By: Thomas

Answer #3:

Python treats in literal string in a special way.
This is so you can type 'n' to mean newline or 't' to mean tab
Since '&' doesn’t mean anything special to Python, instead of causing an error, the Python lexical analyser implicitly adds the extra for you.

Really it is better to use \& or r'&' instead of '&'

The r here means raw string and means that isn’t treated specially unless it is right before the quote character at the start of the string.

In the interactive console, Python uses repr to display the result, so that is why you see the double ”. If you print your string or use len(string) you will see that it is really only the 2 characters

Some examples

>>> 'Here's a backslash: \'
"Here's a backslash: \"
>>> print 'Here's a backslash: \'
Here's a backslash: 
>>> 'Here's a backslash: \. Here's a double quote: ".'
'Here's a backslash: \. Here's a double quote: ".'
>>> print 'Here's a backslash: \. Here's a double quote: ".'
Here's a backslash: . Here's a double quote ".

To Clarify the point Peter makes in his comment see this link

Unlike Standard C, all unrecognized
escape sequences are left in the
string unchanged, i.e., the backslash
is left in the string. (This behavior
is useful when debugging: if an escape
sequence is mistyped, the resulting
output is more easily recognized as
broken.) It is also important to note
that the escape sequences marked as
“(Unicode only)” in the table above
fall into the category of unrecognized
escapes for non-Unicode string
literals.

Answered By: John La Rooy

Answer #4:

>>> '\&' == '&'
True
>>> len('\&')
2
>>> print('\&')
&

Or in other words: '\&' only contains one backslash. It’s just escaped in the python shell’s output for clarity.

Answered By: sepp2k

Answer #5:

There is no extra backslash, it’s just formatted that way in the interactive environment. Try:

print string

Then you can see that there really is no extra backslash.

Answered By: Mark Byers

Answer #6:

printing a list can also cause this problem (im new in python, so it confused me a bit too):

>>>myList = ['\']
>>>print myList
['\']
>>>print ''.join(myList)
 

similarly:

>>>myList = ['&']
>>>print myList
['\&']
>>>print ''.join(myList)
&
Answered By: Kicsi

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