Edit - Stack Overflow

You are not logged in. Your edit will be placed in a queue until it is peer reviewed.

We welcome edits that make the post easier to understand and more valuable for readers. Because community members review edits, please try to make the post substantially better than how you found it, for example, by fixing grammar or adding additional resources and hyperlinks.

Required fields*

Rev

Required fields*

Reversing bits of Python integer

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.

Answer*

Draft saved

Draft discarded

Edit Summary*

Cancel

FYI: the link is now broken. Is this function limited to ints or will it work on numbers of type bignum?

Daniel Henry
– Daniel Henry

2019年03月25日 02:52:30 +00:00
Commented Mar 25, 2019 at 2:52
1

Since the link is broken, the same procedure can be found here with a bit more information: stackoverflow.com/a/30002555/9439097

charelf
– charelf

2020年05月02日 18:03:44 +00:00
Commented May 2, 2020 at 18:03
This works, but is limited to 32-bit integers. Extending it to different-sized integers is possible (following the pattern) but not trivial for non-powers-of-two.

nneonneo
– nneonneo

2024年08月15日 01:10:03 +00:00
Commented Aug 15, 2024 at 1:10
graphics.stanford.edu/~seander/bithacks.html

Ishrak M
– Ishrak M

2025年01月19日 15:42:23 +00:00
Commented Jan 19, 2025 at 15:42

Add a comment |

How to Edit

Correct minor typos or mistakes
Clarify meaning without changing it
Add related resources or links
Always respect the author’s intent
Don’t use edits to reply to the author

How to Format

create code fences with backticks ` or tildes ~
```
like so
```
add language identifier to highlight code
```python
def function(foo):
print(foo)
```
put returns between paragraphs
for linebreak add 2 spaces at end
_italic_ or **bold**
indent code by 4 spaces
backtick escapes `like _so_`
quote by placing > at start of line
to make links (use https whenever possible)

<https://example.com>

[example](https://example.com)

<a href="https://example.com">example</a>

formatting help »
answering help »

How to Tag

A tag is a keyword or label that categorizes your question with other, similar questions. Choose one or more (up to 5) tags that will help answerers to find and interpret your question.

complete the sentence: my question is about...
use tags that describe things or concepts that are essential, not incidental to your question
favor using existing popular tags
read the descriptions that appear below the tag

If your question is primarily about a topic for which you can't find a tag:

combine multiple words into single-words with hyphens (e.g. python-3.x), up to a maximum of 35 characters
creating new tags is a privilege; if you can't yet create a tag you need, then post this question without it, then ask the community to create it for you

popular tags »

lang-py

CollectivesTM on Stack Overflow

Reversing bits of Python integer

Answer*