convert hexadecimal to bytes in python

Question

I want to display the number

0x40000000

as

01000000 00000000 00000000 00000000

with the leading 0 and formatting above

You mean you want to convert hexadecimal to binary.

martineau
– martineau

2012-11-21 13:45:20 +00:00
Commented Nov 21, 2012 at 13:45 — martineau
– martineau, Commented Nov 21, 2012 at 13:45
with byte formatting I think

Dave
– Dave

2012-11-21 13:54:17 +00:00
Commented Nov 21, 2012 at 13:54 — Dave
– Dave, Commented Nov 21, 2012 at 13:54

Jon Clements · Accepted Answer · 2012-11-21 15:25:54Z

2

Maybe not the most flexible way, but:

>>> num = 0x40000000
>>> bits = bin(num)[2:].zfill(32)
# '01000000000000000000000000000000'
>>> ' '.join(bits[i:i+8] for i in xrange(0, 32, 8))
'01000000 00000000 00000000 00000000'

Umm, couldn't post earlier as my broadband was down, but slightly more flexible version...

def fmt_bin(num):
    bits = bin(num)[2:]
    blocks, rem = divmod(len(bits), 8)
    if rem:
        blocks +=1
    filled = bits.zfill(blocks * 8)
    return ' '.join(''.join(el) for el in zip(*[iter(filled)]*8))

edited Nov 21, 2012 at 15:25

answered Nov 21, 2012 at 13:36

Jon Clements

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3 Comments

Eryk Sun Over a year ago

You could use bits = format(num, '032b'). You could get the padding with pad = -8 * (-num.bit_length() // 8), which uses floor division to round up to a multiple of 8.

Jon Clements Over a year ago

@eryksun I updated the answer slightly using something I had open and was playing with, but broadband went down - it appears to work, still not 100% sure if I'm happy, but oh well...

Eryk Sun Over a year ago

I prefer xrange over the copied/zipped iterator in this case. Based on the calculated pad value, I had something like this in mind: bits = '{0:0{1}b}'.format(num, pad).

martineau · Accepted Answer · 2012-11-23 06:22:12Z

1

This will handle arbitrarily large positive numbers:

def long2str(n):
    if n == 0:
        return '00000000'
    s = []
    while n > 0:
        s.append('{:08b}'.format(n & 255))
        n = n >> 8
    return ' '.join(s[::-1])

num = 0x40000000
bignum = 0x4000000040000000
print long2str(num)
print long2str(bignum)

Output:

01000000 00000000 00000000 00000000
01000000 00000000 00000000 00000000 01000000 00000000 00000000 00000000

edited Nov 23, 2012 at 6:22

answered Nov 21, 2012 at 14:45

martineau

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