Re: size_t vs "unsigned long"

[Jan Wielemaker <wielemak@science.uva.nl>]

On Wednesday 03 October 2007 23:36, Pierre Habouzit wrote:
> On Wed, Oct 03, 2007 at 09:19:59PM +0000, Jan Wielemaker wrote:
> > On Wednesday 03 October 2007 22:48, Pierre Habouzit wrote:
> > > On Wed, Oct 03, 2007 at 08:30:04PM +0000, Junio C Hamano wrote:
> > > > Traditionally, inside git, we have used the length of things
> > > > with "unsigned long" for pretty much anything, except where we
> > > > wanted the length exactly sized we used int32_t, uint64_t and
> > > > friends.
> > > >
> > > > A few places pass pointer to unsigned long as the second
> > > > parameter to strbuf_detach(), triggering type mismatch warnings.
> > > > An easy way out is to change strbuf_detach() to take a pointer
> > > > to ulong but I think it is going backwards.  Most places that
> > > > use "unsigned long" can safely be converted (and made more
> > > > correct) to use size_t.
> > >
> > >   Well, afaict, on every linux archs I know of, unsigned longs and
> > > size_t are the same. Though, I don't know if that holds for the msys
> > > port, and if that does not holds, then a s/unsigned long/size_t/ would
> > > help them. Else, for consistency sake, I believe the change is a good
> > > one.
> >
> > Surely on the Microsoft 64-bit compilers size_t is 64-bits and long is
> > 32-bits.  Don't blame me, I'm just the messenger that learned the hard
> > way ...
>
>   Yeah, I've been wondering, and it's the information I had. well, the
> information I had is that sizeof(size_t) is 4 on win32, and 8 on win64,
> OTOH (and this one I'm sure), on windows, longs are 32bits on both (32
> and 64 bits ABIs).
>
>   So replacing unsigned long with size_t's will help the msys port,
> hence I had some insight that this could prove useful, now I'm sure :)

The other types that are useful are intptr_t and uintptr_t, integers
that are guaranteed to be able to hold a pointer. They are defined by
recent versions of the Microsoft compilers and are in <inttypes.h> in
most POSIX systems (at least I didn't have complaints since I started
using them).  I use them for integers holding mangled pointers.  Of
course most clean C programs should not need that.

	--- Jan