Re: Growing stacks in C++

[Hans Aberg]

On 23 Jul 2010, at 00:58, Paul Hilfinger wrote:

> > > BTW: I observe that ISO C++ has a template function
> > > std::uninitialized_copy, defined in <memory>, which ought to work  
> > > for
> > > copying a stack properly.

> > The algorithm is
> >   for (; first != last; ++result, ++first)
> >    new (static_cast<void*>(&*result))
> >     typename iterator_traits<ForwardIterator>::value_type(*first);
> >
> > So it looks as it allocates for each iterator value, which isn't
> > right. The C skeleton allocates a new block and then memcpy's over  
> > the
> > data. Here one should iteratively call the copy-constructors. Then it
> > might be easier to use std::vector or std::deque. Then using the C-
> > skeleton start becoming complicated.
>
> That's not what this means.  The 'new' operator here uses the standard
> placement form, which does no allocation, but uses the given address
> (result) as the pointer value, invoking the copy constructor
> (value_type(*first)) on it.  This is indeed the desired behavior.

Yes, sorry. From what I see (cf. 12.14.13), one may have to define
  void* operator new(size_t, void* p) { return p; }
Or is it in the standard?

  Hans