Question or problem about Python programming:
I have a long Hex string that represents a series of values of different types. I wish to convert this Hex String into a byte array so that I can shift each value out and convert it into its proper data type.
How to solve the problem:
Suppose your hex string is something like
>>> hex_string = "deadbeef"
Convert it to a string (Python ≤ 2.7):
>>> hex_data = hex_string.decode("hex") >>> hex_data "\xde\xad\xbe\xef"
or since Python 2.7 and Python 3.0:
>>> bytes.fromhex(hex_string) # Python ≥ 3 b'\xde\xad\xbe\xef' >>> bytearray.fromhex(hex_string) bytearray(b'\xde\xad\xbe\xef')
bytes is an immutable version of
There is a built-in function in bytearray that does what you intend.
bytearray.fromhex("de ad be ef 00")
It returns a bytearray and it reads hex strings with or without space separator.
provided I understood correctly, you should look for binascii.unhexlify
import binascii a='45222e' s=binascii.unhexlify(a) b=[ord(x) for x in s]
Assuming you have a byte string like so
and you know the amount of bytes and their type you can also use this approach
import struct bytes = '\x12\x45\x00\xAB' val = struct.unpack('
As I specified little endian (using the '<' char) at the start of the format string the function returned the decimal equivalent.
0x12 = 18
0x45 = 69
0xAB00 = 43776
B is equal to one byte (8 bit) unsigned
H is equal to two bytes (16 bit) unsigned
More available characters and byte sizes can be found here
The advantages are..
You can specify more than one byte and the endian of the values
You really need to know the type and length of data your dealing with
You should be able to build a string holding the binary data using something like:
data = "fef0babe" bits = "" for x in xrange(0, len(data), 2) bits += chr(int(data[x:x+2], 16))
This is probably not the fastest way (many string appends), but quite simple using only core Python.