🚀 go-pugleaf

In article <4g3i93$9lp@mulga.cs.mu.OZ.AU> fjh@munta.cs.mu.OZ.AU
(Fergus Henderson) writes:

> 
> "Constantine Antonovich:" <const@Orbotech.Co.IL> writes:
> 
> 
> >  for (unsigned i=0; i<size; ++i) {
> >    (bptr+i)->~B();
> >    new(aptr+i) A;
> >  }
> >

> >int main(void)
> >{
> >  A* arr=foo(2);
> >  delete [] arr;
> 
> This has undefined behaviour.  It contravenes 5.3.5[expr.delete]/2, which
> says that the expression passed to `delete []' must be a pointer to the
> first element of an array of objects allocated with `new []'; this is not
> the case, because although there once was such an array at that memory
> location, its lifetime ended when the memory was overwritten by the calls
> to placement new (see 3.8[basic.life]/1).
> 

Is it relevant here that A and B are unrelated classes? What about the
following code?

A a;

A* as = new A [10];

for (int i = 0; i < 10; ++i) {
    new (&as[i]) A(a);
}
delete [] as;

If this is undefined, how else can I initialize array members with a
nondefault constructor?

Thanks in advance,

-- 
Ian T Zimmerman            +-------------------------------------------+
P.O. Box 13445             I    With so many executioners available,   I
Berkeley, California 94712 I suicide is a really foolish thing to do.  I
USA  <itz@rahul.net>       +-------------------------------------------+
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