From hexadecimal to one's complement in Python

python bit-manipulation ones-complement
user1841870 picture user1841870 · Nov 21, 2012 · Viewed 13.2k times · Source

Is there an easy way to produce a one's complement in python?

For instance, if you take the hex value 0x9E, I need to convert it to 0x61.

I need to swap the binary 1's for 0's and 0's for 1's. It feels like this should be simple.

Answer

Martijn Pieters picture Martijn Pieters · Nov 21, 2012

Just use the XOR operator ^ against 0xFF:

>>> hex(0x9E ^ 0xFF)
'0x61'

If you need to work with values larger than a byte, you could create the mask from the int.bit_length() method on your value:

>>> value = 0x9E
>>> mask = (1 << value.bit_length()) - 1
>>> hex(value ^ mask)
'0x61'
>>> value = 0x9E9E
>>> mask = (1 << value.bit_length()) - 1
>>> hex(value ^ mask)
'0x6161'

Related questions

Bitwise operation and usage

Consider this code: x = 1 # 0001 x << 2 # Shift left 2 bits: 0100 # Result: 4 x | 2 # Bitwise OR: 0011 # Result: 3 x & 1 # Bitwise AND: 0001 # Result: 1 I can understand the arithmetic operators in Python (and other languages), but I never understood 'bitwise' operators quite well. In …

Read More
Two's Complement in Python

Is there a built in function in python which will convert a binary string, for example '111111111111', to the two's complement integer -1?

Read More
bitwise XOR of hex numbers in python

how can we XOR hex numbers in python eg. I want to xor 'ABCD' to '12EF'. answer should be B922. i used below code but it is returning garbage value def strxor(a, b): # xor two strings of different …

Read More