CODEWITHSUNDEEP
pythonpython-3.xcastingintegerbyte
Teodorico Levoff
Teodorico Levoff

Reputation: 1659

How to cast bytes to an int and back to the same bytes?

I have an arbitrary byte in Python that I want to cast into a 64 bit integer and back into the same byte.

I am currently, using this to turn the bytes into an int, where x is a byte I am given:

int.from_bytes(x, "little")

But I'm struggling on how to use int.to_bytes() to convert it back to the same bytes because I'm unsure what to put for length, nothing seems to create the equivalent byte?

Upvotes: -1

Views: 125

Answers (1)

martineau
martineau

Reputation: 123473

I may not understand you question, but consider this:

x = b'deadbeef'
print(f'x -> {x}')    # x -> b'deadbeef'

i = int.from_bytes(x, 'little')
print(f'i -> {i:,}')  # i -> 7,378,415,037,781,730,660

y = i.to_bytes(len(x), 'little')
print(f'y -> {y}')    # y -> b'deadbeef'


# If you don't know the original variable, you can compute the byte length
# like this:

bit_length = i.bit_length() + 1  # Including sign bit.
byte_length = (bit_length + 7) // 8

z = i.to_bytes(byte_length, 'little')
print(f'z -> {z}')    # z -> b'deadbeef'

Upvotes: 1

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