ceph/src/boost/libs/geometry/doc/src/examples/algorithms/is_empty.cpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2 // QuickBook Example
   3
   4 // Copyright (c) 2015, Oracle and/or its affiliates
   5
   6 // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
   7
   8 // Licensed under the Boost Software License version 1.0.
   9 // http://www.boost.org/users/license.html
  10
  11 //[is_empty
  12 //` Check if a geometry is the empty set
  13
  14 #include <iostream>
  15
  16 #include <boost/geometry.hpp>
  17 #include <boost/geometry/geometries/point_xy.hpp>
  18
  19
  20 int main()
  21 {
  22     boost::geometry::model::multi_linestring
  23         <
  24             boost::geometry::model::linestring
  25                 <
  26                     boost::geometry::model::d2::point_xy<double>
  27                 >
  28         > mls;
  29     boost::geometry::read_wkt("MULTILINESTRING((0 0,0 10,10 0),(1 1,8 1,1 8))", mls);
  30     std::cout << "Is empty? " << (boost::geometry::is_empty(mls) ? "yes" : "no") << std::endl;
  31     boost::geometry::clear(mls);
  32     std::cout << "Is empty (after clearing)? " << (boost::geometry::is_empty(mls) ? "yes" : "no") << std::endl;
  33     return 0;
  34 }
  35
  36 //]
  37
  38
  39 //[is_empty_output
  40 /*`
  41 Output:
  42 [pre
  43 Is empty? no
  44 Is empty (after clearing)? yes
  45 ]
  46 */
  47 //]