Question

I have a integer. Lets say,

var = 83 #less than 0xff

And I have a byte.
So let’s say I have byte b and I want to calculate the integer value of

 b-=var #b as an integer value , possibly by eval(b)?

And then I want to turn it back into a byte, how can I do this in python?

Answer 1

If I understood the question, you can do:

>>> chr(ord('x') - 83)
'%'

where 'x' is your byte.

If you’re on Python 3.x

>>> bytes([ord(b'x') - 83])
b'%'

Note ord(b'x') is the same as b'x'[0]

Another example (where the resulting byte is not printable and is shown in the \x00 form):

>>> chr(ord('\x53') - 83)
'\x00'