Re: strange crash after assertion with std::map::iterator

From:

"Igor Tandetnik" <itandetnik@mvps.org>

Newsgroups:

microsoft.public.vc.stl

Date:

Tue, 17 Apr 2007 11:00:28 -0400

Message-ID:

<uSdEkEQgHHA.1312@TK2MSFTNGP03.phx.gbl>

Mycroft Holmes <m.holmes@nospam.it> wrote:

"Igor Tandetnik" <itandetnik@mvps.org> wrote in message
news:u1xYQ4DgHHA.1552@TK2MSFTNGP06.phx.gbl...

Mycroft Holmes <m.holmes@nospam.it> wrote:

the standard is very clear, but bizarre: I'd expect that
default-constructed iterators should behave as default-constructed
pointers (i.e. null)

What makes you think default-constructed pointer is NULL? Consider:

int* p;
assert(p == NULL); // will likely fail

maybe it's just terminology, I call this UNconstructed.
default-constructed would be more like:

template <typename T>
T getDefault()
{
return T();
}

//...

int* p = getDefault<int*>();

Well, you didn't do anything like that to your iterators, you just
declared them with no initializers. Considering that a raw pointer is a
valid iterator (indeed, in some STL implementations vector<T>::iterator
is simply a typedef for T*), I don't see how you can expect the standard
to guarantee any behavior of the iterator above and beyond that of a raw
pointer.

Why do you think you need this "feature"? What did you try to use the
comparison of two uninitialized iterators for?
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925