Python 3.2+Numbers & mathfunction

int.from_bytes

bytes

Class method: reconstruct an integer from a bytes object using the given byte order.

Syntax

int.from_bytes(bytes, byteorder='big', *, signed=False)

The byte order is not stored anywhere, you must know how the data was written: the same two bytes decode to 7 with 'big' and to 1792 with 'little', and a wrong guess raises nothing. With the default signed=False a leading 0xFF reads as a large positive number instead of -1, so pass signed=True whenever the producer used a signed encoding. byteorder only became optional (defaulting to 'big') in Python 3.11.

Examples

print(int.from_bytes(b'\x00\x07', 'big'))  # → 7
print(int.from_bytes(b'\xff', 'little'))    # → 255
print(int.from_bytes(b'\x01\x00', 'little'))  # → 1

See also

Common errors

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