Print bytes to hex

Question

I want to encode string to bytes.

To convert to byes, I used byte.fromhex()

>>> byte.fromhex(\'7403073845\')
b\'t\\x03\\x078E\'         


        

Answer 1

I want to encode string to bytes.

bytes.fromhex() already transforms your hex string into bytes. Don't confuse an object and its text representation -- REPL uses sys.displayhook that uses repr() to display bytes in ascii printable range as the corresponding characters but it doesn't affect the value in any way:

>>> b't' == b'\x74'
True

Print bytes to hex

To convert bytes back into a hex string, you could use bytes.hex method since Python 3.5:

>>> b't\x03\x078E'.hex()
'7403073845'

On older Python version you could use binascii.hexlify():

>>> import binascii
>>> binascii.hexlify(b't\x03\x078E').decode('ascii')
'7403073845'

How can it be displayed as hex like following? b't\x03\x078E' => '\x74\x03\x07\x38\x45'

>>> print(''.join(['\\x%02x' % b for b in b't\x03\x078E']))
\x74\x03\x07\x38\x45

Answer 2

The Python repr can't be changed. If you want to do something like this, you'd need to do it yourself; bytes objects are trying to minimize spew, not format output for you.

If you want to print it like that, you can do:

from itertools import repeat

hexstring = '7403073845'

# Makes the individual \x## strings using iter reuse trick to pair up
# hex characters, and prefixing with \x as it goes
escapecodes = map(''.join, zip(repeat(r'\x'), *[iter(hexstring)]*2))

# Print them all with quotes around them (or omit the quotes, your choice)
print("'", *escapecodes, "'", sep='')

Output is exactly as you requested:

'\x74\x03\x07\x38\x45'