Python/bit_manipulation/binary_twos_complement.py
Leyza 02d9bc66c1
Added binary shifts and twos complement functions to bit manipulation ()
* Added binary shifts and twos complement functions to bit manipulation package

* Fixed problem representing 0 wrong

* More testing

* Fixed problems

* Fixed formatting

* More format fixes

* Format fixes

* Fixed docstrings and added url

* Minor change to url
2021-02-23 11:45:00 +05:30

44 lines
1.1 KiB
Python

# 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()