CGAL users discussion list

[Philipp Moeller <>]

Alessandro Attanasi 
<>
 writes:

> Hi,
>
> I'm a CGAL newbie and I'm learning convex_hull_2D package. I tried to use
> lower_hull_points_2() and upper_hull_points_2() functions but I obtained a
> lot of compilation errors. Maybe I'm not using properly the functions.
>
> I'm using CGAL 4.1 on MacOSX, building the file the cgal script to create
> the cmake building chain
>
> here there is my code

The first error comes from this call:
`CGAL::lower_hull_points_2( points_vect.begin(), points_vect.end(), 
result_vect);`

The third argument should be an OutputIterator, but you pass in a
`std::vector`. Use std::back_inserter(result_vect), if this is what you
want. `CGAL::lower_hull_points_2( points_vect.begin(), points_vect.end(), 
std::back_inserter(result_vect));`

You might also want to clear the vector in between calls.

The variable `ch_points` isn't declared anywhere. I suppose you want
this to be `std::size_t ch_points = result_vect.size();`

A few random things: 
- `typedef enum blabla { FOO } blabla_t;` is not necessary in C++. 
  `enum blabla_t { FOO };` is enough
- I suppose your compiler comes with C++11. Don't initialize vectors with
  `push_back` if you know the elements in advance. Use an
  initializer_list, for example `std::vector<Point_2> v = {p1, p2, p3}`;


[...snipped huge code block and error message...]