'int' is enough for 'length' to migrate code from x86 to x64

[H. S. Teoh via Digitalmars-d]

On Thu, Nov 20, 2014 at 08:18:23AM +0000, Don via Digitalmars-d wrote:
> On Wednesday, 19 November 2014 at 17:55:26 UTC, Andrei Alexandrescu wrote:
> >On 11/19/14 6:04 AM, Don wrote:
> >>Almost everybody seems to think that unsigned means positive. It
> >>does not.
> >
> >That's an exaggeration. With only a bit of care one can use D's
> >unsigned types for positive numbers. Please let's not reduce the
> >matter to black and white.
> >
> >Andrei
> 
> Even in the responses in this thread indicate that about half of the
> people here don't understand unsigned.
> 
> "unsigned" means "I want to use modulo 2^^n arithmetic". It does not
> mean, "this is an integer which cannot be negative".
> 
> Using modulo 2^^n arithmetic is *weird*. If you are using uint/ulong
> to represent a non-negative integer, you are using the incorrect type.
[...]

By that logic, using an int to represent an integer is also using the
incorrect type, because a signed type is *also* subject to module 2^^n
arithmetic -- just a different form of it where the most negative value
wraps around to the most positive values.  Fixed-width integers in
computing are NOT the same thing as unrestricted integers in
mathematics. No matter how you try to rationalize it, as long as you use
hardware fix-width "integers", you're dealing with modulo arithmetic in
one form or another. Pretending you're not, is the real source of said
subtle bugs.


T

-- 
Why waste time learning, when ignorance is instantaneous? -- Hobbes, from Calvin & Hobbes