I'm trying to insert a backslash in a string but when I do this:
s1='cn=Name Surname (123)'
s1[:17] + '\' + s1[17:]
I get
SyntaxError: EOL while scanning string literal
Also, tried this but it inserts 2 backslashes
s1[:17] + '\\' + s1[17:]
The final string should look like this
s1='cn=Name Surname \(123\)'
Here:
>>> s1 = 'cn=Name Surname (123)'
>>> x = s1[:16]+'\\'+s1[16:-1]+'\\'+s1[-1:]
>>> x
'cn=Name Surname \\(123\\)'
>>> print x
cn=Name Surname \(123\)
>>>
You have to print the string. Otherwise, you will see \\ (which is used in the interpreter to show a literal backslash).
>>> s1='cn=Name Surname (123)'
>>> s1[:17] + '\\' + s1[17:]
'cn=Name Surname (\\123)'
It seems like two backslash, but it's actually containing only one backslash.
>>> print(s1[:17] + '\\' + s1[17:])
cn=Name Surname (\123)
>>> print s1[:17] + '\\' + s1[17:-1] + '\\' + s1[-1:]
cn=Name Surname (\123\)
If you're just entering it in the python command line interpreter and pressing enter, it will show up as two backslashes because the interpreter shows the escape character. However, if you saved it to a file, or if you used it in a "print" command it will suppress the escape character and print the actual value, which in this case is just one backslash.
Can something like this suffice?
print(s1.replace('(', '\\(').replace(')', '\\)'))
for folder in Chart_Folders:
files = os.listdir(path + '\\' + folder)
print(files)
indeed this works
Related
I need to escape all special character and then add back slash () into input parameters using python. I have done something but it's not working. My code is below.
rname = request.POST.get('rname')
ename = re.escape(rname)
add_slash = ename + '\'
Here I need to escape all special character first and then add the \ with that string.
A backslash also needs to be escaped, like so
add_slash = ename + '\\'
**Hello Satya, **
Your Solution
Try this below code,
rname = request.POST.get('rname')
ename = (re.escape(rname)) + "\\"
add_slash = ename
More knowledge about string literal so read below link,
https://docs.python.org/2.0/ref/strings.html
I hope my answer is helpful.
If any query so c
This question already has answers here:
Why do backslashes appear twice?
(2 answers)
How should I write a Windows path in a Python string literal?
(5 answers)
Closed 4 years ago.
I have a dictionary:
my_dictionary = {"058498":"table", "064165":"pen", "055123":"pencil"}
I iterate over it:
for item in my_dictionary:
PDF = r'C:\Users\user\Desktop\File_%s.pdf' %item
doIt(PDF)
def doIt(PDF):
part = MIMEBase('application', "octet-stream")
part.set_payload( open(PDF,"rb").read() )
But I get this error:
IOError: [Errno 2] No such file or directory: 'C:\\Users\\user\\Desktop\\File_055123.pdf'
It can't find my file. Why does it think there are double backslashes in file path?
The double backslash is not wrong, python represents it way that to the user. In each double backslash \\, the first one escapes the second to imply an actual backslash. If a = r'raw s\tring' and b = 'raw s\\tring' (no 'r' and explicit double slash) then they are both represented as 'raw s\\tring'.
>>> a = r'raw s\tring'
>>> b = 'raw s\\tring'
>>> a
'raw s\\tring'
>>> b
'raw s\\tring'
For clarification, when you print the string, you'd see it as it would get used, like in a path - with just one backslash:
>>> print(a)
raw s\tring
>>> print(b)
raw s\tring
And in this printed string case, the \t doesn't imply a tab, it's a backslash \ followed by the letter 't'.
Otherwise, a string with no 'r' prefix and a single backslash would escape the character after it, making it evaluate the 't' following it == tab:
>>> t = 'not raw s\tring' # here '\t' = tab
>>> t
'not raw s\tring'
>>> print(t) # will print a tab (and no letter 't' in 's\tring')
not raw s ring
So in the PDF path+name:
>>> item = 'xyz'
>>> PDF = r'C:\Users\user\Desktop\File_%s.pdf' % item
>>> PDF # the representation of the string, also in error messages
'C:\\Users\\user\\Desktop\\File_xyz.pdf'
>>> print(PDF) # "as used"
C:\Users\user\Desktop\File_xyz.pdf
More info about escape sequences in the table here. Also see __str__ vs __repr__.
Double backslashes are due to r, raw string:
r'C:\Users\user\Desktop\File_%s.pdf' ,
It is used because the \ might escape some of the characters.
>>> strs = "c:\desktop\notebook"
>>> print strs #here print thinks that \n in \notebook is the newline char
c:\desktop
otebook
>>> strs = r"c:\desktop\notebook" #using r'' escapes the \
>>> print strs
c:\desktop\notebook
>>> print repr(strs) #actual content of strs
'c:\\desktop\\notebook'
save yourself from getting a headache you can use other slashes as well.
if you know what I saying. the opposite looking slashes.
you're using now
PDF = 'C:\Users\user\Desktop\File_%s.pdf' %item
try to use
**
PDF = 'C:/Users/user/Desktop/File_%s.pdf' %item
**
it won't be treated as a escaping character .
It doesn't. Double backslash is just the way of the computer of saying backslash. Yes, I know this sounds weird, but think of it this way - in order to represent special characters, backslash was chosen as an escaping character (e.g. \n means newline, and not the backslash character followed by the n character). But what happens if you actually want to print (or use) a backslash (possibly followed by more characters), but you don't want the computer to treat it as an escaping character? In that case we escape the backslash itself, meaning we use a double backslash so the computer will understand it's a single backslash.
It's done automatically in your case because of the r you added before the string.
alwbtc #
I dare say: "I found the bug..."
replace
PDF = r'C:\Users\user\Desktop\File_%s.pdf' %item
doIt(PDF)`
with
for item in my_dictionary:
PDF = r'C:\Users\user\Desktop\File_%s.pdf' % mydictionary[item]
doIt(PDF)`
in fact you were really looking for File_pencil.pdf (not File_055123.pdf).
You were sliding the index dictionary not its contents.
This forum topic maybe a side-effect.
This question already has answers here:
Why do backslashes appear twice?
(2 answers)
How should I write a Windows path in a Python string literal?
(5 answers)
Closed 4 years ago.
I have a dictionary:
my_dictionary = {"058498":"table", "064165":"pen", "055123":"pencil"}
I iterate over it:
for item in my_dictionary:
PDF = r'C:\Users\user\Desktop\File_%s.pdf' %item
doIt(PDF)
def doIt(PDF):
part = MIMEBase('application', "octet-stream")
part.set_payload( open(PDF,"rb").read() )
But I get this error:
IOError: [Errno 2] No such file or directory: 'C:\\Users\\user\\Desktop\\File_055123.pdf'
It can't find my file. Why does it think there are double backslashes in file path?
The double backslash is not wrong, python represents it way that to the user. In each double backslash \\, the first one escapes the second to imply an actual backslash. If a = r'raw s\tring' and b = 'raw s\\tring' (no 'r' and explicit double slash) then they are both represented as 'raw s\\tring'.
>>> a = r'raw s\tring'
>>> b = 'raw s\\tring'
>>> a
'raw s\\tring'
>>> b
'raw s\\tring'
For clarification, when you print the string, you'd see it as it would get used, like in a path - with just one backslash:
>>> print(a)
raw s\tring
>>> print(b)
raw s\tring
And in this printed string case, the \t doesn't imply a tab, it's a backslash \ followed by the letter 't'.
Otherwise, a string with no 'r' prefix and a single backslash would escape the character after it, making it evaluate the 't' following it == tab:
>>> t = 'not raw s\tring' # here '\t' = tab
>>> t
'not raw s\tring'
>>> print(t) # will print a tab (and no letter 't' in 's\tring')
not raw s ring
So in the PDF path+name:
>>> item = 'xyz'
>>> PDF = r'C:\Users\user\Desktop\File_%s.pdf' % item
>>> PDF # the representation of the string, also in error messages
'C:\\Users\\user\\Desktop\\File_xyz.pdf'
>>> print(PDF) # "as used"
C:\Users\user\Desktop\File_xyz.pdf
More info about escape sequences in the table here. Also see __str__ vs __repr__.
Double backslashes are due to r, raw string:
r'C:\Users\user\Desktop\File_%s.pdf' ,
It is used because the \ might escape some of the characters.
>>> strs = "c:\desktop\notebook"
>>> print strs #here print thinks that \n in \notebook is the newline char
c:\desktop
otebook
>>> strs = r"c:\desktop\notebook" #using r'' escapes the \
>>> print strs
c:\desktop\notebook
>>> print repr(strs) #actual content of strs
'c:\\desktop\\notebook'
save yourself from getting a headache you can use other slashes as well.
if you know what I saying. the opposite looking slashes.
you're using now
PDF = 'C:\Users\user\Desktop\File_%s.pdf' %item
try to use
**
PDF = 'C:/Users/user/Desktop/File_%s.pdf' %item
**
it won't be treated as a escaping character .
It doesn't. Double backslash is just the way of the computer of saying backslash. Yes, I know this sounds weird, but think of it this way - in order to represent special characters, backslash was chosen as an escaping character (e.g. \n means newline, and not the backslash character followed by the n character). But what happens if you actually want to print (or use) a backslash (possibly followed by more characters), but you don't want the computer to treat it as an escaping character? In that case we escape the backslash itself, meaning we use a double backslash so the computer will understand it's a single backslash.
It's done automatically in your case because of the r you added before the string.
alwbtc #
I dare say: "I found the bug..."
replace
PDF = r'C:\Users\user\Desktop\File_%s.pdf' %item
doIt(PDF)`
with
for item in my_dictionary:
PDF = r'C:\Users\user\Desktop\File_%s.pdf' % mydictionary[item]
doIt(PDF)`
in fact you were really looking for File_pencil.pdf (not File_055123.pdf).
You were sliding the index dictionary not its contents.
This forum topic maybe a side-effect.
I'm so confused... why/how is a different from b?! Why don't they print the same thing?
>>> a = '"'
>>> a
'"'
>>> b = "'"
>>> b
"'"
The strings are not presented differently. Their presentation is just adjusted to avoid having to quote the contained quote. Both ' and " are legal string literal delimiters.
Note that the contents of the string are very different. " is not the same string as '; a == b is (patently) False.
Python would have to use a \ backslash for the " or ' character otherwise. If you use both characters in a string, then python is forced to use quoting:
>>> '\'"'
'\'"'
>>> """Tripple quoted means you can use both without escaping them: "'"""
'Tripple quoted means you can use both without escaping them: "\''
As you can see, the string representation used by Python still uses single quotes and a backslash to represent that last string.
Recently I made the following observation:
>>> x= "\'"
>>> x
"'"
>>> y="'"
>>> y
"'"
>>> print x
'
>>> print y
'
Can anyone please explain why is it so. I am using python 2.7.x. I know well about escape sequences.
I want to do the following:
I have a string with single quotes in it and I have to enter it in a database so I need to replace the instance of single quote(') with a backslash followed by a single quote(\'). How can I achieve this.
Inside a pair of "", you don't need to escape the ' character. You can, of course, but as you've seen it's unnecessary and has no effect whatsoever.
It'd be necessary to escape if you were to write a ' inside a pair of '' or a " inside a pair of "":
x = '\''
y = "\""
EDIT :
Regarding the last part in the question, added after the edit:
I have a string with single quotes in it and I have to enter it in a database so I need to replace the instance of single quote(') with a backslash followed by a single quote(\'). How can I achieve this
Any of the following will work, notice the use of raw strings for avoiding the need to escape special characters:
v = "\\'"
w = '\\\''
x = r'\''
y = r"\'"
print v, w, x, y
> \' \' \' \'