Re: int problems on amd64

["Liam R. E. Quin" <liam holoweb net>]

On Tue, 2005-03-29 at 17:28 +0200, Fabio Rotondo wrote:
> Roland Smith wrote:
> [...] suppose you have to write a qsort callback:
>
> void qsort(void *base, size_t nmemb, size_t size, int(*compar)(const
> void *, const void *));
>
> suppose the "const void *" is actually an int value. By downcasting it
> to int, gcc gives you a warning.
it'll be a pointer to an int, of course, not an int.  But since an int
is smaller than a void *pointer, it'll work fine.  The addresses might
sometimes overlap, but that's OK.  That's why it's declared as a pointer
to an object of type "void".

The reason it's a warning and not an error to cast between pointer and
integer is that it's sometimes both necessary and correct.  More often
you should cast between a pointer and a long, of course.

Liam

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