Python built-in base-256 to base-10 conversion and vice versa?

Question

I want to store large numbers (200-300 digits +) in a text file, so I want to know if there is either a built-in function that converts base-10 numbers to base-256 equivalents and vice versa in Python, or whether there is a module that supports this (much like the default hex() function).

Answer 1

'Base256' is essentially binary bytes. While one can interpret the result as latin-1 encoded text, that does not seem as much use. So I would not suffix the resulting file as .txt.

That aside, the struct module us used to convert data to and from bytes. A relatively simple example:

>>> import struct
>>> b = struct.pack('HhL', 33333, -33, 3333333333)
>>> b
b'5\x82\xdf\xffU\xa1\xae\xc6'
>>> struct.unpack('HhL', b)
(33333, -33, 3333333333)

When writing to or reading from a file, remember to open in binary mode.

Answer 2

Integers have the to_bytes-method:

base256 = number.to_bytes((number.bit_length()+7)//8, 'big')

number =int.from_bytes(base256, 'big')