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Subject: Re: to check given no. is power of 2
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Date: Wed, 25 May 2005 13:15:51 GMT
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aveo wrote:
> 
> i need a C code that checks given no. is power of 2 or not without
> checking any condition.

int qpwrof2(unsigned long n)
{
   return (n && (!(n & (n-1))));
} /* untested */

assuming n == 0 is not considered a power of 2.  Function names
beginning with 'is' are reserved, so I use q for query.  The above
should handle values up to 32 bits and return 0 or 1 only.

-- 
Some useful references about C:
  <http://www.ungerhu.com/jxh/clc.welcome.txt>
  <http://www.eskimo.com/~scs/C-faq/top.html>
  <http://benpfaff.org/writings/clc/off-topic.html>
  <http://anubis.dkuug.dk/jtc1/sc22/wg14/www/docs/n869/> (C99)
  <http://www.dinkumware.com/refxc.html>           (C-library}
  <http://gcc.gnu.org/onlinedocs/>                  (GNU docs)