plz help with a c++ macro

can someone please explain the meaning/purpose of this macro?

#define myMacro(a, b) ( (int) &( ( ( a * ) 0 )->b ) )


Thanks!!

In what context did you see this used? I cannot really discern its purpose as it looks like it may involve dereferencing a null pointer.

this looks pretty much like the "offsetof" macro/function in C

http://72.14.235.132/search?q=cache:...&gl=my&strip=1