Print a variable in hexadecimal in Python

Question

I'm trying to find a way to print a string in hexadecimal. For example, I have this string which I then convert to its hexadecimal value.

my_string = "deadbeef"
my_hex = my_string.decode('hex')

How can I print my_hex as 0xde 0xad 0xbe 0xef?

To make my question clear... Let's say I have some data like 0x01, 0x02, 0x03, 0x04 stored in a variable. Now I need to print it in hexadecimal so that I can read it. I guess I am looking for a Python equivalent of printf("%02x", my_hex). I know there is print '{0:x}'.format(), but that won't work with my_hex and it also won't pad with zeroes.

Answer 1

You mean you have a string of bytes in my_hex which you want to print out as hex numbers, right? E.g., let's take your example:

>>> my_string = "deadbeef"
>>> my_hex = my_string.decode('hex')  # python 2 only
>>> print my_hex
Þ ­ ¾ ï

This construction only works on Python 2; but you could write the same string as a literal, in either Python 2 or Python 3, like this:

my_hex = "\xde\xad\xbe\xef"

So, to the answer. Here's one way to print the bytes as hex integers:

>>> print " ".join(hex(ord(n)) for n in my_hex)
0xde 0xad 0xbe 0xef

The comprehension breaks the string into bytes, ord() converts each byte to the corresponding integer, and hex() formats each integer in the from 0x##. Then we add spaces in between.

Bonus: If you use this method with unicode strings (or Python 3 strings), the comprehension will give you unicode characters (not bytes), and you'll get the appropriate hex values even if they're larger than two digits.

Addendum: Byte strings

In Python 3 it is more likely you'll want to do this with a byte string; in that case, the comprehension already returns ints, so you have to leave out the ord() part and simply call hex() on them:

>>> my_hex = b'\xde\xad\xbe\xef'
>>> print(" ".join(hex(n) for n in my_hex))
0xde 0xad 0xbe 0xef

Answer 2

Convert the string to an integer base 16 then to hexadecimal.

print hex(int(string, base=16))

These are built-in functions.

http://docs.python.org/2/library/functions.html#int

Example

>>> string = 'AA'
>>> _int = int(string, base=16)
>>> _hex = hex(_int)
>>> print _int
170
>>> print _hex
0xaa
>>>