python 'long' hex value to decimal

Question

hi i want to hex value to decimal without loop(because 'speed' problem)

ex)
>>> myvalue = "\xff\x80\x17\x90\x12\x44\x55\x99\x90\x12\x80"
>>> int(myvalue)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '\xff\x80\x17\x90\x12DU\x99\x90\x12\x80'

>>> ord(myvalue)
Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
TypeError: ord() expected a character, but string of length 11 found
>>>

anyone helps ?

rel: http://stackoverflow.com/questions/444591/convert-a-string-of-bytes-into-an-int-python — georg, Jun 03 '12 at 14:37
What do you want to get as output? List of character codes? Something else? — Vitaly S., Jun 03 '12 at 14:40

score 4 · Accepted Answer · answered Jun 03 '12 at 14:33

4

Your number seems to be an integer given as binary data. In Python 3.2, you can convert it to a Python integer with int.from_bytes():

>>> myvalue = b"\xff\x80\x17\x90\x12\x44\x55\x99\x90\x12\x80"
>>> int.from_bytes(myvalue, "big")
308880981568086674938794624

The best solution I can come up with for Python 2.x is

>>> myvalue = "\xff\x80\x17\x90\x12\x44\x55\x99\x90\x12\x80"
>>> int(myvalue.encode("hex"), 16)
308880981568086674938794624L

Since this does not involve a Python loop, it should be pretty fast, though.

answered Jun 03 '12 at 14:33

Sven Marnach

574,206
118
941
841

I'm pretty sure there is a loop in there somewhere though :) – wroniasty Jun 03 '12 at 14:39
1

@wroniasty: That's why I wrote "no Python loop". – Sven Marnach Jun 03 '12 at 14:39
@wroniasty The loop would be written in C and not Python. – jamylak Jun 03 '12 at 14:40
@jamylak Actually this depends on the Python implementation, it may as well be a Python loop. – wroniasty Jun 03 '12 at 14:44

score 0 · Answer 2 · answered Jun 03 '12 at 14:48

0

The struct module will most likely not use a loop:

import struct
valuesTuple = struct.unpack ('L', myValue[:4])

Of course this limits the numerical values to basic data types (int, long int, etc.)

answered Jun 03 '12 at 14:48

wroniasty

7,884
2
32
24

This method won't even work for the example given in the question, so I don't think it is a good answer. – Sven Marnach Jun 03 '12 at 15:11
@SvenMarnach still it's the only one not involving a loop (probably) ;) – wroniasty Jun 03 '12 at 18:54

python 'long' hex value to decimal

2 Answers2