structure element offsets

[Jonathan Hahn]

In article <1096 at spice.cs.cmu.edu> bader at spice.cs.cmu.edu (Miles Bader) writes:
>Is there any way of finding the offset of a structure element from
>the beginning of a structure in a portable AND efficient way?

Try:

#define OFFSET(elem, type)	(&(((type *)0)->elem))

This utilizes a pointer of address 0, for which the address of the
element reference yeilds the offset of the element.

-jonathan hahn
hahn at ames-nas.arpa