Article View: comp.lang.c.moderated
Article #2416Re: Efficiency Question : bits vs. bytes (or anything else, for that matter)
From: Lawrence Kirby
Date: Wed, 27 Mar 1996 23:59
Date: Wed, 27 Mar 1996 23:59
40 lines
1883 bytes
1883 bytes
In article <4jbciv$2kk@solutions.solon.com> vjarnot@mnw.net "Asmodeus" writes:
>
>I have set up an array in the following manner (obviously I just need
>0 or 1) :
>
>typedef struct my_bits {
> unsigned the_bit : 1;
>};
I assume you meant:
typedef struct {
unsigned the_bit : 1;
} my_bits;
The first problem here is that the struct does *not* consist of just one bit.
The smallest size it can have is 1 byte (char) and it could well be more
depending on how your compiler allocates bitfields.
>my_bits the_array[800][800];
>
> My question is this : I have read that some operations ( =,+,- are
>what I use) are slower when performed on bits as opposed to other
>types.
On most archetectures, yes.
> My objective is to optimize the code for speed, and I figured
>using less memory would help me do so, now I'm having doubts. So what
>is more efficient, bits or some other type???
Unless you ave platform specific information to the contrary you should
assume that int/unsigned int are the most efficient integer types.
--
-----------------------------------------
Lawrence Kirby | fred@genesis.demon.co.uk
Wilts, England | 70734.126@compuserve.com
-----------------------------------------
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Path: arc1-ca.pugleaf.net!solon.com!not-for-mail From: Lawrence Kirby <fred@genesis.demon.co.uk> Newsgroups: comp.lang.c.moderated Subject: Re: Efficiency Question : bits vs. bytes (or anything else, for that matter) Date: 27 Mar 1996 17:59:34 -0600 Organization: none Sender: clc@solutions.solon.com Approved: clc@solutions.solon.com Message-ID: <4jckp6$a3i@solutions.solon.com> References: <4jbciv$2kk@solutions.solon.com> Reply-To: fred@genesis.demon.co.uk NNTP-Posting-Host: solutions.solon.com X-NNTP-Posting-Host: genesis.demon.co.uk X-Newsreader: Demon Internet Simple News v1.27 X-Mail2News-Path: genesis.demon.co.uk