Re: [boost] Re: A pure C/C++ question

From: David Abrahams (dave_at_[hidden])
Date: 2002-08-22 11:07:32

From: "Victor A. Wagner, Jr." <vawjr_at_[hidden]>\

> At Thursday 2002/08/22 01:23, you wrote:
> >Maxim Shemanarev writes:
> >  > > If the committee is seriously considering ways to handle stuff,
how
> > about
> >  > > dealing with the two results returned by almost every integer
divide
> >  > > instruction... quotient and remainder.
> >  >
> >  > Right. That's another thing. But in this case if you write x=a/b;
y=a%b; a
> >  > compiler at least  *can try* to optimize this. In case of x*a/b it
cannot
> >  > because it's not allowed to!
> >
> >Everyone is forgetting that integer overflow on signed types results in
> >undefined behaviour.
>
> This is an artifact of the language definition (a poor one, IMO).  When
_I_
> learned multiplication (way back when I was 6 or 7) I noticed pretty
quick
> that if I multiplied a n digit number by an m digit number I _might_ get
an
> m+n digit number.  The first several computers I worked on always
produced
> a "two word" product from two "one word" operands.  I was somewhat
> disappointed to learn that the HLL's all seemed to ignore this "basic
fact"
> of mathematics.  <shrug> it's what we're stuck with, tho I still consider
> it mostly intellectual laziness that led to it.  Especially with strongly
> typed languages now.

But every one of these languages has a max-sized integral type. Would you
disallow

    65536L * 3L

in C++98?

-Dave

-----------------------------------------------------------
           David Abrahams * Boost Consulting
dave_at_[hidden] * http://www.boost-consulting.com