Editing Python programming (section)

=== Formatting with bits, decimals, and hexadecimals ===

<big>Convert text numbers into text hexadecimal values</big>
<pre>>>> f = '{:02x}'

>>> f.format(255)
'ff'

>>> f.format('255') < -- cannot directly convert from string number to hexadecimal number
Traceback (most recent call last):
  File "<pyshell#6>", line 1, in <module>
    f.format('255')
ValueError: Unknown format code 'x' for object of type 'str'

>>> f.format(int('255')) < -- cast string number into integer then apply string formatting
'ff' < -- hexadecimal string</pre>

<big>Randomly create some bits then format as hexadecimal. Then dynamically specify format using nested parametrized formats.</big>
<pre>>>> from random import getrandbits

>>> '0x{0:08x}'.format(getrandbits(64))
'0x43c5e5b009f7dc1b'

>>> '0x{0:08x}'.format(getrandbits(64))
'0xce3d5ffeaf7d693b'

>>> '0x{:08x}'.format(getrandbits(64))
'0x9b3fcfc7b31b9c1a'

>>> '0x{:0{width}x}'.format(getrandbits(64), width=8)
'0x8f6aae777885c555'

>>> '{:0{width}x}'.format(getrandbits(64), width=8)
'f5f900fba39f78ef'

>>> '{:0{width}x}'.format(getrandbits(64), width=8)
'4f3f855b2d6f4abd'

>>> '{:0{width}x}'.format(getrandbits(32), width=8)
'7791644a'

>>> '{:0{width}x}'.format(getrandbits(32), width=16)
'00000000b498791e'

>>> def get_random_hex_string(length_of_hex):
	return '{:0{length}x}'.format(getrandbits(length_of_hex * 4), length=length_of_hex)

>>> get_random_hex_string(8)
'c61e3d06'

>>> get_random_hex_string(16)
'0c81d7dda113c0fd'

>>> get_random_hex_string(32)
'270cb00a17f5dfc79f65b15ebfd57195'

>>> get_random_hex_string(64)
'eb06490b3d208afed79c1f380ab6c7f9c23c16319aa0928d6ac3609fa2c620af'</pre>

<big>Create a function to randomly return a hexadecimal string of varied length with integer parameter.</big>
<pre>def get_random_hex_string(length_of_hex):
    """
    Function takes the desired total length of hexadecimal characters and returns text string composed of random hexadecimal characters.
    :param length_of_hex: integer representing the total number of hexadecimal digits desired
    :return: text string of precise length and random hexadecimal values
    """
    return '{:0{length}x'.format(getrandbits(length_of_hex * 4), length=length_of_hex)</pre>

<big>Create random IPv4 address an octet at a time</big>
<pre>>>> from random import getrandbits
	
>>> hf = '{:02x}'
	
>>> hl = list()
	
>>> for i in range(4):
	hl.append(hf.format(getrandbits(8))) < -- build a list of four random octets (32 bits)

>>> hl
['73', 'dc', 'd9', '36']

>>> ''.join(hl) < -- join the octets
	
'73dcd936' < -- IPv4 representation in compact hexadecimal format</pre>