Python Forum

i know python has such a thing but cannot remember the terms or names for this. my guesses are not helping my search.

foo('\\'+'n'+'\\'+'t') -> '\n\t'

e.g having the backslash codes (any of them, not just these 2), convert them to the actual vales. this is conversion done to string literals somewhere in the python interpreter. but i have seen this before, so i know exists as a simple function call, but my searches are all failing. repr() does the reverse.

I'm not quite sure I understand what you want.

Does this hit on it?

>>> chr(10)
'\n'
>>> ord('\n')
10

Edit:
I think these links hit on your question actually:
How do I un-escape a backslash-escaped string in python?
how do I .decode('string-escape') in Python3?

i was hoping it was usable in python 2. i guess i will have to get this old code cleaned up and use it..

67 LINES OF OLD CODE

#-----------------------------------------------------------------------------
# function      decode_control
#
# purpose       Decode control characters and other character formatted stuff
#               in ASCII strings.
#
# argument      string with encoded control characters
#
# returns       string with decoded control characters
#
# note          \a or ^g = alarm
#               \b or ^h = backspace
#               \t or ^i = tab
#               \n or ^j = newline
#               \v or ^k = vertical tab
#               \f or ^l = formfeed
#               \r or ^m = carriage return
#               \e or ^[ = escape
#               \\ = literal backslash
#               ^^ = literal carat
#               \0 = raw zero (warning: may cause string problems)
#               \[0-3][0-7][0-7] converts octal to raw
#               \x[0-9a-fA-F][0-9a-fA-F] converts hexadecimal to raw
#-----------------------------------------------------------------------------
def decode_control( istr ):
    b = {'a':7,'b':8,'t':9,'n':10,'v':11,'f':12,'r':13,'e':27,'\\':92,}
    ostr = ''
    while len(istr) > 0:
        c = istr[0]
        if c == '^':
            if len(istr) < 2: return ostr
            c = istr[1]
            istr = istr[2:]
            if c == '^':
                ostr += '^'
                continue
            ostr += chr( ord( c ) % 32 )
        elif c == '\\':
            if len(istr) < 2: return ostr
            c = istr[1]
            if c in b:
                ostr += chr(b[c])
                istr = istr[2:]
                continue
            if len(istr) < 4:
                return ostr
            if istr[1] == 'x' or istr[1] == 'X':
                try:
                    c = int( istr[2:4], 16 )
                    istr = istr[4:]
                except:
                    if istr[1] == '0': c = ord( istr[1] )
                    else: c = 0
                    istr = istr[2:]
            else:
                try:
                    c = int( istr[1:3], 8 )
                    istr = istr[4:]
                except:
                    if istr[1] == '0': c = ord( istr[1] )
                    else: c = 0
                    istr = istr[2:]
            ostr += chr( c )
        else:
            ostr += istr[0]
            istr = istr[1:]
    return ostr

You mean marking the string as 'raw' by putting "r" in front of it?

>>> x = '\\n'
>>> y = r'\n'
>>> x == y
True

warning: very old thread

(Oct-18-2016, 03:08 PM)nilamo Wrote: [ -> ]You mean marking the string as 'raw' by putting "r" in front of it?
>>> x = '\\n'
>>> y = r'\n'
>>> x == y
True

no.

i mean converting the kinds of backslash codes you might see expressed in source code, from being in actual strings to the binary result.

if i have code that reads input into a string and i type in a backslash and an 'r' i will have 2 characters, a backslash and an 'r'. source code to get exactly the same thing would be '\r'. but source code is merely explaining this; not how it is actually gotten. wherever those 2 characters come from, i want to apply the same effect as you see in source code:

    foo = '\r'

in the above case the variable named foo will end up with just 1 character. what i want (and have coded) is a function to do that.

my struggle has been explaining what i am doing. the "raw" concept is not what i am doing, although a reference to it might explain it to you. i'm thinking of it as an encoding.

perhaps this code would explain better what i have and what i want that can do the conversion

   abc = chr(92)
   xyz = chr(114)
   woot = convert(abc+xyz)
   print(ord(woot))

this would print out 13. what i want is that convert() function in a form that supports all such control codes.

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Mekire

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nilamo

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