CGAL users discussion list

[Marc Glisse <>]

On Sun, 20 Nov 2016, irene89 wrote:

> Hi everybody, I'm new to C++ and CGAL. I'm tryng to obtain an alpha shape
> from a point set in the plane and to do that I was first trying to run the
> following example:
>
> http://doc.cgal.org/latest/Alpha_shapes_2/Alpha_shapes_2_2ex_alpha_shapes_2_8cpp-example.html
>
> with this set of point:
> (0,2), (-0.5,1), (0,1), (0.5,1), (-2,0), (-1,0), (0,0), (1,0), (2,0),
> (-0.5,-1), (0,-1), (0.5,-1), (0,-2)
>
> The points are saved in a file data.txt with the same exact format above and
> this file is in the same directory of the .cpp. Obviously I changed the line
> in the example
>
>  std::ifstream is("./data/fin", std::ios::in);
>
> with the line
>
>  std::ifstream is("data.txt", std::ios::in);

Did you look at the file data/fin that you are replacing? It is formatted 
completely differently from your file...
"Reading 0 points from file" is a strong hint that you need to take a 
closer look at the file. It should look like:

13
0 2
-0.5 1
...

--
Marc Glisse