add missing example file

Convex_hull_3/examples/Convex_hull_3/extreme_indices_3.cpp

@@ -0,0 +1,42 @@
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/convex_hull_3.h>
+#include <CGAL/Extreme_points_traits_adapter_3.h>
+#include <CGAL/IO/read_off_points.h>
+
+#include <boost/iterator/counting_iterator.hpp>
+
+#include <vector>
+#include <fstream>
+
+
+typedef CGAL::Exact_predicates_inexact_constructions_kernel      K;
+typedef K::Point_3                                               Point_3;
+
+int main(int argc, char* argv[])
+{
+  std::ifstream in( (argc>1)? argv[1] : "data/star.off");
+
+  if(!in)
+  {
+    std::cerr<< "Cannot open input file." <<std::endl;
+    return 1;
+  }
+
+  std::vector<Point_3> points;
+  CGAL::read_off_points(in, std::back_inserter(points));
+
+  //This will contain the extreme vertices
+  std::vector<std::size_t> extreme_point_indices;
+
+  //call the function with the traits adapter for vertices
+  CGAL::extreme_points_3(CGAL::make_range(boost::counting_iterator<std::size_t>(0),
+                                          boost::counting_iterator<std::size_t>(points.size())),
+                         std::back_inserter(extreme_point_indices),
+                         CGAL::make_extreme_points_traits_adapter(CGAL::make_property_map(points)));
+  //print the number of extreme vertices
+  std::cout << "Indices of points on the convex hull are:\n";
+  std::copy(extreme_point_indices.begin(), extreme_point_indices.end(), std::ostream_iterator<std::size_t>(std::cout, " "));
+  std::cout << "\n";
+
+  return 0;
+}