From: Caleb Clausen <vikkous@...>
Date: 2010-01-04T16:38:17+09:00
Subject: Re: bitwise shift help

On 1/3/10, Kvetch Kvetch <kvetch@gmail.com> wrote:
> Kvetch Kvetch wrote:
>> Hello, I am new to Ruby and was wondering if there is an easier/faster
>> way to determine if a bit is set in a number. For example,
[snip]
>> y = 1 << 3
>> x = 0b1011000010
>>
>> if ( x & y ) == 1
>> puts "The 3rd bit is set"
>> else
>> puts "The 3rd bit is not set"
>> end
>>
>> Is there a better/faster method of achieving this bit check?
>
> Actually I suppose the bit check should read
> if ( x & y ) >= 1
> Or I am still totally off.

There's nonzero?, which ought to be a tad faster than >=1. So, write
this instead:

  if ( x & y ).nonzero?

Or, if you incorporate Axel's suggestion to use Fixnum#[] as well, then:

  if x[3].nonzero?