polymorphism - 64 bit - va_arg - advanced

Does any one see how to have a type in a va_arg that can accept int(32 bit) or pointers(64bit) in a 64 bit environment.

This page suggests that VC++ will support %I in the future. I was wondering if there is any way to do this portably.
http://msdn.microsoft.com/library/en...iderations.asp

For example:

We have INT_PTR ip = va_arg(marker, void *);

The problem is that when you have something like this:

printf("%I", 100);

The va_arg will read in 64bits(sizeof(void *)) when only 32 bits(sizeof(int)) have been supplied.

I suspect this is impossible. Anyone have any ideas.

PS. Is it possible that default type promotions will promote everything to 64bit despite sizeof(int) and sizeof(long) being 32 bit.

Thanks.

Use %p or %n to handle pointers in a printf-style format specification.
Since you specify a (void*) type to va_arg(), you should pass in a (void*) type:

Code:

---

    printf("%p", (void*)10);

---

gg

Thanks for the reply, that's exactly what I have done. I assume MS will implement %I as a compiler extension.

It's interesting that int and long have stayed at 32bits.

On an unrelated note I found this site:
http://www.opus1.com/vmsdoc/progtool...4/6180ptoc.htm

It seems to be a nicely formatted html rewrite of the C standard from the programmer's perspective(rather than the implementor), although some of the information is specific to Compaq C.