TopoDS_Shape shape; if (shape.IsNull()) { std::cout << "Shape is null" << std::endl; }
TopoDS_Shape shape = BRepPrimAPI_MakeBox(10, 10, 10); if (!shape.IsNull()) { std::cout << "Shape is not null" << std::endl; }In this example, we use the BRepPrimAPI_MakeBox() function to create a box shape and assign it to the TopoDS_Shape object. We then use the IsNull() function to check if it is null. Since we added geometric entities to it, it will return false. Overall, the TopoDS package library is used for representing and manipulating geometric shapes in Open CASCADE Technology.