C89 foreach macro

Anyone else ever write a foreach macro in C? I find it useful to have every now and again, but I find myself needing to rewrite the macro for every different large project. Maybe I'm not doing it right...

>>4
#define foreach_array(a,i) for (i = 0; i < sizeof a / sizeof a[0]; i++)
#define foreach_list(l,np) for (np = l; np; np = np->next)