🚀 go-pugleaf

>     	register long result;
>     	result = p1->data - p2->data;

(where p1-data is a pointer to a struct)
and 

>     	register long result;
>     	result = (long) p1->data - (long) p2->data;

should not be the same in any C, unless the size of the struct is 1.  This
is because C scales pointer differences to yield the number of things pointed
at between the pointers, not the number of bytes.

	p1->data - p2->data   

is equivalent to

	((long)p1->data - (long)p2->data) / sizeof(*p1->data).

This will be zero if the two structs pointed at overlap.
-- 
-------------------------------------------
Mark G. Mendel, Network Systems Corporation
ihnp4!umn-cs!hyper!mark

All opinions expressed herein, even the most arbitrary, are defended by my 
employer with religious fervor.