Re: simple string question
On 8 Sep, 05:39, Steven D'Aprano
ste...@remove.this.cybersource.com.au wrote:
On Mon, 07 Sep 2009 01:54:09 -0700, Niklas Norrthon wrote:
Others have answered how to replace '\\n' with '\n'. For a more general
approach which will handle all string escape sequences allowed in python
(including '\xdd' and similar), python's eval can be used:
eval can do so much more than handle escape sequences:
Yes, eval is really cool :-)
quoted_string = ') or __import__(os).system(echo \'Pwn3d\';#rm -rf /'
print eval('str(%s)' % quoted_string)
Every (bad) programmer should pass untrusted strings to eval as a quick
and unsafe way to do trivial transformations.
It all depends on the origin of the strings of course.
I must admit that I didn't think of str.decode('string_escape') which
of course is the correct way to solve the problem (after inspecting
a sample of the input data to make sure it conforms to the
specification, and isn't rtf or some such).
I probably should decrease the volume of quick and dirty one time
hacks I produce...
/Niklas
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Re: simple string question
On Sep 6, 10:29 pm, jwither jwit...@sxder4kmju.com wrote: Given a string (read from a file) which contains raw escape sequences, (specifically, slash n), what is the best way to convert that to a parsed string, where the escape sequence has been replaced (specifically, by a NEWLINE token)? James Withers I believe \n is a newline. As is \r\n and \r. Choose your demon. mystring = mystring.replace(\n, demon) FYI. If you are reading from a file, you can iterate over the lines without having to worry about newlines: fi = open(path_to_file, 'r') for line in fi: process_line(line) ~Sean -- http://mail.python.org/mailman/listinfo/python-list
Re: simple string question
On Sep 6, 11:29 pm, jwither jwit...@sxder4kmju.com wrote: Given a string (read from a file) which contains raw escape sequences, (specifically, slash n), what is the best way to convert that to a parsed string, where the escape sequence has been replaced (specifically, by a NEWLINE token)? James Withers 1) What is a parsed string? 2) What is a NEWLINE token? -- http://mail.python.org/mailman/listinfo/python-list
Re: simple string question
On Sun, Sep 6, 2009 at 10:29 PM, jwitherjwit...@sxder4kmju.com wrote: Given a string (read from a file) which contains raw escape sequences, (specifically, slash n), what is the best way to convert that to a parsed string, where the escape sequence has been replaced (specifically, by a NEWLINE token)? There's probably a more general method covering all the escape sequences, but for just \n: your_string = your_string.replace(\\n, \n) Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: simple string question
Chris Rebert c...@rebertia.com wrote in message news:mailman.1075.1252306208.2854.python-l...@python.org... On Sun, Sep 6, 2009 at 10:29 PM, jwitherjwit...@sxder4kmju.com wrote: Given a string (read from a file) which contains raw escape sequences, (specifically, slash n), what is the best way to convert that to a parsed string, where the escape sequence has been replaced (specifically, by a NEWLINE token)? There's probably a more general method covering all the escape sequences, but for just \n: your_string = your_string.replace(\\n, \n) Cheers, Chris -- http://blog.rebertia.com Thanks! (the others are more likely to be errors than deliberate anyway) James Withers -- http://mail.python.org/mailman/listinfo/python-list
Re: simple string question
There's probably a more general method covering all the escape sequences, but for just \n: your_string = your_string.replace(\\n, \n) py s = hello\\r\\n py s 'hello\\r\\n' py s.decode(string_escape) 'hello\r\n' py -- http://mail.python.org/mailman/listinfo/python-list
Re: simple string question
On 7 Sep, 07:29, jwither jwit...@sxder4kmju.com wrote:
Given a string (read from a file) which contains raw escape sequences,
(specifically, slash n), what is the best way to convert that to a parsed
string, where the escape sequence has been replaced (specifically, by a
NEWLINE token)?
James Withers
Others have answered how to replace '\\n' with '\n'. For a more
general approach which will handle all string escape sequences allowed
in python (including '\xdd' and similar), python's eval can be used:
quoted_string = 'hello\\nworld\\x21\\tand\\tgood\\040\\x47ood bye!'
print quoted_string
'hello\nworld\x21\tAnd\tgood\040\x47ood bye!'
print eval('str(%s)' % quoted_string)
hello
world! And good Good bye!
If the string isn't quoted just enclosed it in quotes first:
unquoted_string = 'hello\\nworld\\x21\\tand\\tgood\\040\\x47ood bye!'
print unquoted_string
hello\nworld\x21\tAnd\tgood\040\x47ood bye!
print eval('str(%s)' % unquoted_string)
hello
world! And good Good bye!
/Niklas Norrthon
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Re: simple string question
On Mon, 7 Sep 2009 15:29:23 +1000 jwither jwit...@sxder4kmju.com wrote: Given a string (read from a file) which contains raw escape sequences, (specifically, slash n), what is the best way to convert that to a parsed string, where the escape sequence has been replaced (specifically, by a NEWLINE token)? I don't know what your actual requirement is but maybe this fits: exec(print '%s' % x) -- D'Arcy J.M. Cain da...@druid.net | Democracy is three wolves http://www.druid.net/darcy/| and a sheep voting on +1 416 425 1212 (DoD#0082)(eNTP) | what's for dinner. -- http://mail.python.org/mailman/listinfo/python-list
Re: simple string question
On Mon, 07 Sep 2009 01:54:09 -0700, Niklas Norrthon wrote:
Others have answered how to replace '\\n' with '\n'. For a more general
approach which will handle all string escape sequences allowed in python
(including '\xdd' and similar), python's eval can be used:
eval can do so much more than handle escape sequences:
quoted_string = ') or __import__(os).system(echo \'Pwn3d\';#rm -rf /'
print eval('str(%s)' % quoted_string)
Every (bad) programmer should pass untrusted strings to eval as a quick
and unsafe way to do trivial transformations.
http://en.wikipedia.org/wiki/Code_injection
--
Steven
--
http://mail.python.org/mailman/listinfo/python-list
Re: simple string question
ryles ryle...@gmail.com wrote in message news:b96be200-9762-4f92-bd0d-9be076bcd...@y20g2000vbk.googlegroups.com... There's probably a more general method covering all the escape sequences, but for just \n: your_string = your_string.replace(\\n, \n) py s = hello\\r\\n py s 'hello\\r\\n' py s.decode(string_escape) 'hello\r\n' py Even though that's what I asked for, I'll stick with the replace for now. But it's cool though: I can embed generic uni-code as well as simple escape sequences! Thanks, James Withers. -- http://mail.python.org/mailman/listinfo/python-list
