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From: ttwang@polyslo.CalPoly.EDU (Thomas Wang)
Newsgroups: comp.lang.c++
Subject: calculate member byte offset
Message-ID: <1989Oct5.193826.24178@polyslo.CalPoly.EDU>
Date: 5 Oct 89 19:38:26 GMT
Reply-To: ttwang@polyslo.CalPoly.EDU (Thomas Wang)
Distribution: usa
Organization: Cal Poly State University -- San Luis Obispo
Lines: 28

I need to know the byte offset of 'header' in class 'foo' before any
'foo' object is allocated.

class foo
{
public:
  int grr;
  int header;
  void alloc();
};

void foo::alloc()
{
  cout << (&(this->header)) - this << "\n";   // bomb?
}

main()
{
  ((foo*) 0) -> alloc();   // bomb?
}

Just how portable is this kind of code?

 -Thomas Wang ("This is a fantastic comedy that Ataru and his wife Lum, an
                invader from space, cause excitement involving their neighbors."
                  - from a badly translated Urusei Yatsura poster)

                                                     ttwang@polyslo.calpoly.edu