[phobos] sizediff_t

[Walter Bright]

Why is it a misnomer? When, in C, would you use ssize_t rather than 
ptrdiff_t? Are they ever a different type?

(If you're going to do it, it should be ssize_t.)

Andrei Alexandrescu wrote:
> I was aware of the presence of ptrdiff_t in druntime. Part of my point 
> is that the name is sometimes a misnomer in C (which led to the 
> definition of ssize_t) and even more so in D, where entire programs 
> can be written without ever using the notion of "pointer".
>
> So my question boils down, I think, to: do we go with "ssize_t" or 
> "sizediff_t"?
>
>
> Andrei
>
> On 1/10/11 10:27 PM, Walter Bright wrote:
>> Yes we do, ptrdiff_t, defined in object.
>>
>> Andrei Alexandrescu wrote:
>>> One question - we don't have a type for the difference of two size_t
>>> objects. That would be int on m32 and long on m64. C has historically
>>> used ptrdiff_t for that, but not all size differences are pointer
>>> differences, so gnu has acknowledged that by defining ssize_t ("signed
>>> size_t" I suppose).
>>>
>>> While being in a crunch making some 64-bit changes I defined the type
>>> sizediff_t. I wonder if that's okay as a permanent solution.
>>>
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