I am looking for a way to prefix strings in python with a single backslash, e.g. "]" -> "]". Since "\" is not a valid string in python, the simple
mystring = '\' + mystring
won't work. What I am currently doing is something like this:
mystring = r'\@@@' + mystring
mystring.replace('@@@','')
While this works most of the time, it is not elegant and also can cause problems for strings containing "@@@" or whatever the "filler" is set to. Is there a bette way of doing this?
You need to escape the backslash with a second one, to make it a literal backslash:
mystring = "\\" + mystring
Otherwise it thinks you're trying to escape the ", which in turn means you have no quote to terminate the string
Ordinarily, you can use raw string notation (r'string'), but that won't work when the backslash is the last character
The difference between print a and just a:
>>> a = 'hello'
>>> a = '\\' + a
>>> a
'\\hello'
>>> print a
\hello
a it prints the escaped string (the repr). print a displays it correctlyPython strings have a feature called escape characters. These allow you to do special things inside as string, such as showing a quote (" or ') without closing the string you're typing
So when you typed
mystring = '\' + mystring
the \' is an escaped apostrophe, meaning that your string now has an apostrophe in it, meaning it isn't actually closed, which you can see because the rest of that line is coloured.
To type a backslash, you must escape one, which is done like this:
>>> aBackSlash = '\\'
>>> print(aBackSlash)
\
You should escape the backslash as follows:
mystring = "\\" + mystring
This is because if you do '\' it will end up escaping the second quotation. Therefore to treat the backslash literally, you must escape it.
>>> s = 'hello'
>>> s = '\\' + s
>>> print
\hello
>>> mystring = 'it actually does work'
>>> mystring = '\\' + mystring
>>> print mystring
\it actually does work
As a different way of approaching the problem, have you considered string formatting?
r'\%s' % mystring
or:
r'\{}'.format(mystring)
mystring = '\\' + mystring-- you must "escape" literal backslash characters in a string with another backslash.