Re: Question about bits (debugging>

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Mon, 31 Mar 2008 16:20:58 -0400
Message-ID:
<fsrh3b$1aq$1@news.datemas.de>
Ian Collins wrote:

Victor Bazarov wrote:

Andy Champ wrote:

Jerry Coffin wrote:

In article <7b28c8e1-0dd7-48ee-ac33-40e7dc517139
@p25g2000hsf.googlegroups.com>, enki034@yahoo.com says...

[ ... ]

          temp=-128;

My guess is that this isn't what you intended. I'd guess you meant
'-=' instead of '=-'.

Interestingly enough, at one time in the history of C, this would
actually have done the same thing, but that's purely historical,
and so long ago I doubt it ever made it into C++ at all.


I think you're right.

But might I suggest using

bits[0] = (temp & 128) ? 1 : 0;

in place of

if(temp >= 128){
    bits[0] = 1;
    temp=-128;
}

It'll give the optimiser more chance to work.


Doesn't look equivalent. The value of 'temp' doesn't change in the
expression case, and it does in the 'if' case.


I was just about to post the same response when I realised the
suggested form does not require temp to be updated, all the bits can
be tested in place.


I agree; my reply was out of context.

V
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