在 Python 中以十六进制打印变量

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? Eg, 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
>>> 

Answer 3

Another answer with later print/format style is:

res[0]=12
res[1]=23
print("my num is 0x{0:02x}{1:02x}".format(res[0],res[1]))

Answer 4

Use

print " ".join("0x%s"%my_string[i:i+2] for i in range(0, len(my_string), 2))

like this:

>>> my_string = "deadbeef"
>>> print " ".join("0x%s"%my_string[i:i+2] for i in range(0, len(my_string), 2))
0xde 0xad 0xbe 0xef
>>>

On an unrelated side note ... using string as a variable name even as an example variable name is very bad practice.

Answer 5

You can try something like this I guess:

new_str = ""
str_value = "rojbasr"
for i in str_value:
    new_str += "0x%s " % (i.encode('hex'))
print new_str

Your output would be something like this:

0x72 0x6f 0x6a 0x62 0x61 0x73 0x72

Answer 6

A way that will fail if your input string isn't valid pairs of hex characters...:

>>> import binascii
>>> ' '.join(hex(ord(i)) for i in binascii.unhexlify('deadbeef'))
'0xde 0xad 0xbe 0xef'