I need to do some work with bytes in Python and I’ve come across a byte string I don’t really understand:
b"H\x00\x84\xffQ\x00\xa6\xff+\x00\x96\xff\xc2\xffI\xff\xa5\xff'\xff\x8a\xff\x19\xff\x19\xff\xf6\xfe\xb0\xfe\xc7\xfeJ\xfel\xfe\xf8\xfd+\xfe\xef\xfd:\xfe\xc3\xfd*\xfe_\xfd\xdf\xfd\n\xfd\xa3\xfd\xc6\xfcq\xfd\xbd\xfc?\xfd"
So according to what I know, bytes should be represented as \xhh, where hh are hexadecimal values (from 0 to f). However, in the third segment, there is \xffQ, and farther on there are other characters which shouldn’t appear: I, ‘, *, :, ? etc.
I’ve used hex() method to see what would be the outcome, and I got this:
480084ff5100a6ff2b0096ffc2ff49ffa5ff27ff8aff19ff19fff6feb0fec7fe4afe6cfef8fd2bfeeffd3afec3fd2afe5ffddffd0afda3fdc6fc71fdbdfc3ffd
As you can see, some parts of the hex are the same, but e.g. \xffQ was changed into ff51. I need to append some data to this byte string, so I’d like to know what’s going on there (or how to get the same result).
>Solution :
Both repr and str when processing a bytes object will print ASCII characters where possible. Otherwise their hexadecimal values will be shown in the form \xNN.
It might help you to visualise the content if you print it as all hexadecimal as follows:
b = b"H\x00\x84\xffQ\x00\xa6\xff+\x00\x96\xff\xc2\xffI\xff\xa5\xff'\xff\x8a\xff\x19\xff\x19\xff\xf6\xfe\xb0\xfe\xc7\xfeJ\xfel\xfe\xf8\xfd+\xfe\xef\xfd:\xfe\xc3\xfd*\xfe_\xfd\xdf\xfd\n\xfd\xa3\xfd\xc6\xfcq\xfd\xbd\xfc?\xfd"
print(''.join(hex(b_) for b_ in b))
Output:
0x480x00x840xff0x510x00xa60xff0x2b0x00x960xff0xc20xff0x490xff0xa50xff0x270xff0x8a0xff0x190xff0x190xff0xf60xfe0xb00xfe0xc70xfe0x4a0xfe0x6c0xfe0xf80xfd0x2b0xfe0xef0xfd0x3a0xfe0xc30xfd0x2a0xfe0x5f0xfd0xdf0xfd0xa0xfd0xa30xfd0xc60xfc0x710xfd0xbd0xfc0x3f0xfd