CGAL users discussion list

[Camille Wormser <>]

> Error   17      error C2678: binary '<' : no operator found which takes a
> left-hand operand of type 'const Vertex_handle' (or there is no  
> acceptable
> conversion)        C:\Program Files\Microsoft Visual Studio
> 8\VC\include\functional        143
>
> Please could you give us an example or a link to an example using map 
> []
> properly on Polyhedron::Vertex_handle?

Hello,
The std::map needs a comparison operator for the keys, i.e., the  
Vertex_handles, which do not provide such an operator. You could add a  
comparison class in the following way:

/* compares the corresponding pointers */
template < class Handle >
struct Handle_comparison
{
   bool operator() (const Handle& h1, const Handle& h2) const
   {
       return &(*h1) < &(*h2);
   }
};

and then define the std::map as

std::map < Polyhedron::Vertex_handle, int,
          Handle_comparison<Polyhedron::Vertex_handle> > listVertex;

--
Camille