how to convert a string to hex

how to convert a string to hex - Printable Version

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how to convert a string to hex - Skaperen - Jan-22-2017

what is the best way to convert a string to hexadecimal?

the purpose is to get the character codes to see what is being read in from a file.

i already have command line tools that display the file in hexadecimal. i want to match that up with what the python script is doing. something that is suitable for making such tools might work. i tried binascii.hexlify() but it wanted a bytes-like object. i have a string for now.

for example i have a misbehaving script. i want to drop in a slim piece of code to have it print the string in hex.

RE: how to convert a string to hex - ichabod801 - Jan-22-2017

str.encode gives you the bytes representation of the string. From that you can use the hex method to get the hex values:

>>> s = 'The quick brown fox jumps over the lazy dog.'.encode('utf-8')
>>> s
b'The quick brown fox jumps over the lazy dog.'
>>> s.hex()
'54686520717569636b2062726f776e20666f78206a756d7073206f76657220746865206c617a7920646f672e'

That's Python 3.x of course. Sting handling was one of the big changes between 2.x and 3.x.

RE: how to convert a string to hex - snippsat - Jan-22-2017

And when convert to bytes,then decode method become active(dos not work on string).

>>> s = 'The quick brown fox jumps over the lazy dog.'.encode('utf-8')
>>> s
b'The quick brown fox jumps over the lazy dog.'
>>> # Back to string
>>> s.decode('utf-8')
'The quick brown fox jumps over the lazy dog.'

Can also just call encode decode.

>>> s = 'The quick brown fox jumps over the lazy dog.'
>>> s = s.encode()
>>> s
b'The quick brown fox jumps over the lazy dog.'
>>> s.decode()
'The quick brown fox jumps over the lazy dog.'

RE: how to convert a string to hex - Skaperen - Jan-23-2017

(Jan-22-2017, 11:52 AM)snippsat Wrote: And when convert to bytes,then decode method become active(dos not work on string).

>>> s = 'The quick brown fox jumps over the lazy dog.'.encode('utf-8')
>>> s
b'The quick brown fox jumps over the lazy dog.'
>>> # Back to string
>>> s.decode('utf-8')
'The quick brown fox jumps over the lazy dog.'

Can also just call encode decode.

>>> s = 'The quick brown fox jumps over the lazy dog.'
>>> s = s.encode()
>>> s
b'The quick brown fox jumps over the lazy dog.'
>>> s.decode()
'The quick brown fox jumps over the lazy dog.'

so what do i get out of this (a string) that i didn't have before (a string). so why not just keep a copy of the original string?

s = 'The quick brown fox jumps over the lazy dog.'
b = s.encode()

now i have both. or is there something special about the string result of s.encode().decode() ???

RE: how to convert a string to hex - snippsat - Jan-23-2017

(Jan-23-2017, 01:43 AM)Skaperen Wrote: now i have both. or is there something special about the string result of s.encode().decode() ???

You can of course do it like this if you need a copy.
Both have now own space in memory.

>>> s = 'The quick brown fox jumps over the lazy dog.'
>>> b = s.encode()
>>> id(s)
64508296
>>> id(b)
64396640
>>> b
b'The quick brown fox jumps over the lazy dog.'
>>> s
'The quick brown fox jumps over the lazy dog.'

>>> help(id)
Help on built-in function id in module builtins:

id(...)
   id(object) -> integer
   
   Return the identity of an object.  This is guaranteed to be unique among
   simultaneously existing objects.  (Hint: it's the object's memory address.)

So a little more on this Unicode stuff,this was a big change for Python 3.
Just writing Unicode in Python 3.x and it work.
In Python 3 are all strings sequences of Unicode character.

# Python 3.6
>>> print('Spicy jalapeño ☂')
Spicy jalapeño ☂

# Python 2.7
>>> print('Spicy jalapeño ☂')
Spicy jalapeÃ±o â˜‚

Taking in stuff from outside in to Python 3.x,
we need to give it a encoding to be a string.
So open() was given a new parameter encoding='utf-8'.

with open('some_file', encoding='utf-8') as f:
    print(f.read())

There are also parameter to taken a malformed encoded file like errors='ignore' errors='replace'

with open('some_file', encoding='utf-8', errors='ignore') as f:
    print(f.read())

So save(as utf-8) and read in Spicy jalapeño ☂

with open('uni.txt', encoding='utf-8') as f:
    print(f.read()) # spicy jalapeño ☂

# Read in as ascii,but ignore UnicodeDecodeError
with open('uni.txt', encoding='ascii', errors='ignore') as f:
    print(f.read()) # Spicy jalapeo

# Read in as ascii,and replace errors
with open('uni.txt', encoding='ascii', errors='replace') as f:
    print(f.read()) # Spicy jalape��o ���