Flávio Etrusco schreef op 12 mrt '13:
> On 3/11/13, Darius Blaszyk <dhkblas...@zeelandnet.nl> wrote: > >> I'm stuck porting a macro from C. Below is the original define. The part I'm struggeling with is the right most part after the - sign. #define GETNEXT(x) ((LList *)(((char *) x) - ((char *) & (((LList *)0)^.next)))) Does anyone know what is meant with the define? Obviously LList is a linked list struct that has a prev and next variable. But what does the & and 0 mean? Appreciate any help. Regards, Darius > > AFAICS they mean "address" and "nil", respectively, so that part will > return the offset of "next" inside and item of LList. > > -Flávio So here is what I made based on your and Henry's mail. However still it does not seem to work, although other ported code might be at fault of course :) //#define GETNEXT(x) ((LList *)(((char *) x) - ((char *) & (((LList *)0)->.next)))) function GETNEXT(x: pLList): pLList; inline; begin exit(pLList(pchar(x) - pchar(pLList(nil)^.next))); end; And let LList be declared as: LList = record len: integer; next, prev: pLList; name: PChar; nextname: PChar; flag: integer; end; Then I still don't understand what this does: if list^.next <> nil then list^.nextname := GETNEXT(list^.next)^.name; Regards, Darius
_______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
