How to convert between iterators and pointers?

From: Leon (mrcool031179_at_yahoo.com)
Date: 12/20/03


Date: 20 Dec 2003 02:45:15 -0800

Hi all.

I'm a bit confused about the use of STL iterators and pointers, and I was
wondering if maybe you could give me some pointers ;)

Is it possible to convert between iterators and pointers pointing to the
same type, e.g. between "std::set<Vertex>::iterator vi" and "Vertex *" ?

I found a quote in the MSVC STL documentation, saying:
  "Remember that an object pointer can always serve as a
  random-access iterator. Therefore, it can serve as any category
  of iterator, as long as it supports the proper read/write access
  to the sequence it designates."

But I can't seem to assign a "Vertex *" to an iterator, like this:
  Vertex v;
  Vertex *pv = &v;
  std::set<Vertex>::iterator vi = pv;

Is there a right way of letting an iterator point to the same object as a
pointer?

Using an iterator as a pointer also doesn't seem to work. For example:
  // Edge constructor declaration:
  // Edge(Vertex *pv1, Vertex *pv2);
  std::set<Vertex>::iterator vi1, vi2;
  // [Set vi1 and vi2 here]
  Edge e(vi1, vi2); // Won't compile, saying "No user-defined
                     // conversion operator available"

Instead, I have to resort to:
  Edge e(&(*vi1), &(*vi2));

Is this normal, or am I doing something wrong?

Thanks in advance,
Leon.