Re: [AD] mode-list updates.

[Stepan Roh <stepan@xxxxxxxxxx>]

On Tue, 2 Oct 2001, Martijn Versteegh wrote:

> On Tue, Oct 02, 2001 at 02:17:26PM +0200, Henrik Stokseth wrote:
> >On Tuesday 02 October 2001 02:50, Peter Wang wrote:
> >
> >> Btw, in both modesel.c and bgfxapi.cpp, `realloc' is being used
> >> incorrectly.
> >
> >Oh really? i think you are mistaken here, unless you can convince me
> >otherwise.
> >
> >realloc has some cool features. for example if ptr is NULL it works
> >equivalent to malloc and if size is 0 it works equivalent to free.
> >
> AFAIK this is not true for every compiler out there.
>
> it is for gcc, and I think it is for msvc, but I'm not sure if it's
> in the ansi c specs.

realloc(NULL, size) is good according to ISO/ANSI C and means the same as
malloc(size)

realloc(ptr, 0) is not any special (read: "there is no notice regarding
that in specs") according to ISO/ANSI C. You can't be sure what will
happen in this case. Stupid realloc() implementation could have malloc(0)
return zero-sized block of memory aligned to 4 KB (for example :-).

Following information is from various libc implementations (just for
completness):

IRIX 6.5

     If size is zero, the storage associated with ptr is freed and realloc
     returns the same result as does malloc(0).

SunOS 5.8

     If size is 0 and ptr is not a null pointer, the space pointed to is
     made available for further allocation

GNU glibc-2.2.3

     if size is equal to zero, the call is equivalent to free(ptr).

Have a nice day.

Stepan Roh