Xref: utzoo comp.lang.c:15345 comp.std.c:652
Path: utzoo!attcan!uunet!lll-winken!ames!vsi1!daver!athsys!jim
From: jim@athsys.uucp (Jim Becker)
Newsgroups: comp.lang.c,comp.std.c
Subject: BIT Counting: C programming problem
Message-ID: <225@tityus.UUCP>
Date: 9 Jan 89 23:11:02 GMT
Organization: Athena Systems, Inc., Sunnyvale, CA
Lines: 33


	I was recently asked a problem to which there are a number of
solutions, I'm looking for opinions as to the best of those different
solutions.

	The problem is the most efficient method to simply count the
number of on bits in a sixteen bit short. This is a really easy
exercise, but one that has a variety of different approaches. I would
be interested in the opinions of programmers out there, an efficient
algorithm that is understandable.

	Assume that this is a basic sample algorithm:

		int	
		BitCount( num )
		short	num;
		{
			int	count	= 0;

			while( num ) {

				count	+= (num &  1);
				num	 = (num >> 1);
			}

			return count;
		}

	Is this efficient? Is this understandable? What is a better
algorithm? Please email your responses. I'll report the results of
algorithms when the votes are in. Thanx!

-Jim Becker 	...!sun!athsys!jim