Python: Reversibly encode alphanumeric string to integer

Question

I want to convert a string (composed of alphanumeric characters) into an integer and then convert this integer back into a string:

string --> int --> string

In other words, I want to represent an alphanumeric string by an integer.

I found a working solution, which I included in the answer, but I do not think it is the best solution, and I am interested in other ideas/methods.

Please don't tag this as duplicate just because a lot of similar questions already exist, I specifically want an easy way of transforming a string into an integer and vice versa.

This should work for strings that contain alphanumeric characters, i.e. strings containing numbers and letters.

Answer 1

Here's what I have so far:

First define an string

m = "test123"

string -> bytes

mBytes = m.encode("utf-8")

bytes -> int

mInt = int.from_bytes(mBytes, byteorder="big")

int -> bytes

mBytes = mInt.to_bytes(((mInt.bit_length() + 7) // 8), byteorder="big")

bytes -> string

m = mBytes.decode("utf-8")

All together

m = "test123"
mBytes = m.encode("utf-8")
mInt = int.from_bytes(mBytes, byteorder="big")
mBytes2 = mInt.to_bytes(((mInt.bit_length() + 7) // 8), byteorder="big")
m2 = mBytes2.decode("utf-8")
print(m == m2)

---

Here is an identical reusable version of the above:

class BytesIntEncoder:

    @staticmethod
    def encode(b: bytes) -> int:
        return int.from_bytes(b, byteorder='big')

    @staticmethod
    def decode(i: int) -> bytes:
        return i.to_bytes(((i.bit_length() + 7) // 8), byteorder='big')

If you're using Python <3.6, remove the optional type annotations.

Test:

>>> s = 'Test123'
>>> b = s.encode()
>>> b
b'Test123'

>>> BytesIntEncoder.encode(b)
23755444588720691
>>> BytesIntEncoder.decode(_)
b'Test123'
>>> _.decode()
'Test123'