Checking if an Integer is an Exact Binary Power

[Walter Bright via Digitalmars-d]

On 4/24/2016 8:33 AM, Andrei Alexandrescu wrote:
> On 04/24/2016 02:57 AM, deadalnix wrote:
>> On Saturday, 23 April 2016 at 15:29:08 UTC, Andrei Alexandrescu wrote:
>>> Yah, that's the canonical. I forgot why I chose (x & -x) > (x - 1)
>>> over it.
>>
>> I'm not sure why do you test against x - 1 when you could test for
>> equality. Not only it looks like it is going to require an extra
>> computation (x - 1) but also it doesn't work for 0.
>
> So if you do (x & -x) == x that returns 1 for x == 0. For many applications you
> want to yield 0. So you test for (x & -x) > (x - 1) such that for x == 0 the
> right hand side is a large number. -- Andrei

This sort of stuff should go on wiki.dlang.org page!