Reversing bits of Python integer
bit-manipulation, integer, python
Solution
int('{:08b}'.format(n)[::-1], 2)
You can specify any filling length in place of the 8. If you want to get really fancy,
b = '{:0{width}b}'.format(n, width=width)
int(b[::-1], 2)
lets you specify the width programmatically.
Problem
Given a decimal integer (eg. 65), how does one reverse the underlying bits in Python? i.e.. the following operation: ``` 65 → 01000001 → 10000010 → 130 ``` It seems that this task can be broken down into three steps: - Convert the decimal integer to binary representation - Reverse the bits - Convert back to decimal Steps #2 and 3 seem pretty straightforward (see this and this SO question related to step #2), but I'm stuck on step #1. The issue with step #1 is retrieving the full decimal representation with filling zeros (ie. 65 = 01000001, not 1000001). I've searched around, but I can't seem to find anything.