## Python, bit_manipulation, binary_twos_complement.py

``````# Information on 2's complement: https://en.wikipedia.org/wiki/Two%27s_complement

def twos_complement(number: int) -> str:
"""
Take in a negative integer 'number'.
Return the two's complement representation of 'number'.

>>> twos_complement(0)
'0b0'
>>> twos_complement(-1)
'0b11'
>>> twos_complement(-5)
'0b1011'
>>> twos_complement(-17)
'0b101111'
>>> twos_complement(-207)
'0b100110001'
>>> twos_complement(1)
Traceback (most recent call last):
...
ValueError: input must be a negative integer
"""
if number > 0:
raise ValueError("input must be a negative integer")
binary_number_length = len(bin(number)[3:])
twos_complement_number = bin(abs(number) - (1 << binary_number_length))[3:]
twos_complement_number = (
(
"1"
+ "0" * (binary_number_length - len(twos_complement_number))
+ twos_complement_number
)
if number < 0
else "0"
)
return "0b" + twos_complement_number

if __name__ == "__main__":
import doctest

doctest.testmod()
``````