Forward declaration error

[game]

Dear Users,,

I am using OpenCASCADE environment to read STL file! Well the problem with c++ knowledge!!
I face a problem, with forward declaration error with the following

void StlReadIn::STL_Import()
{

	          std::string FileName;
	          std::cout<<"\nEnter the file name\n";
                  std::cin>>FileName;
	          OSD_Path aFile(FileName.c_str());
		     Standard_Boolean ReturnValue = Standard_True;

		     Handle(StlMesh_Mesh) aSTLMesh = RWStl::ReadFile(aFile);
		     TopoDS_Compound ResultShape;
		     BRep_Builder CompoundBuilder;
		     CompoundBuilder.MakeCompound(ResultShape);

		     Standard_Integer NumberDomains = aSTLMesh->NbDomains(); // The error shows here
		     Standard_Integer iND;
		     gp_XYZ p1, p2, p3;
		     TopoDS_Vertex Vertex1, Vertex2, Vertex3;
		     TopoDS_Face AktFace;
		     TopoDS_Wire AktWire;
		     BRep_Builder B;
		     Standard_Real x1, y1, z1;
		     Standard_Real x2, y2, z2;
		     Standard_Real x3, y3, z3;

		     StlMesh_MeshExplorer aMExp (aSTLMesh);

		//     BRepBuilderAPI_MakeWire WireCollector;
		     for (iND=1;iND<=NumberDomains;iND++)
		     {
		          for (aMExp.InitTriangle (iND); aMExp.MoreTriangle (); aMExp.NextTriangle ())
		          {
		               aMExp.TriangleVertices (x1,y1,z1,x2,y2,z2,x3,y3,z3);
		               p1.SetCoord(x1,y1,z1);
		               p2.SetCoord(x2,y2,z2);
		               p3.SetCoord(x3,y3,z3);

		               if ((!(p1.IsEqual(p2,0.0))) && (!(p1.IsEqual(p3,0.0))))
		               {
		                    Vertex1 = BRepBuilderAPI_MakeVertex(p1);
		                    Vertex2 = BRepBuilderAPI_MakeVertex(p2);
		                    Vertex3 = BRepBuilderAPI_MakeVertex(p3);

		                    AktWire = BRepBuilderAPI_MakePolygon( Vertex1, Vertex2, Vertex3, Standard_True);

		                    if( !AktWire.IsNull())
		                    {
		                         AktFace = BRepBuilderAPI_MakeFace( AktWire);
		                         if(!AktFace.IsNull())
		                              CompoundBuilder.Add(ResultShape,AktFace);
		                    }
		               }
		          }
		     }
		     TopoDS_Shape aShape = ResultShape;
}

Error message:

stlreadin.cpp:26:47: error: invalid use of incomplete type ‘struct StlMesh_Mesh’
/usr/local/oce-0.9.1/include/oce/Handle_StlMesh_Mesh.hxx:23:7: error: forward declaration of ‘struct StlMesh_Mesh’

Please suggestion, and correction! I am sorry but, i do not understand the problem and the meaning of the message!

Hope to receive ur comments
Thank you very much for the help

Game

[MikeyBoy]

A forward declaration is where you declare that something is a class or a struct, but don't provide the full definition of that class/struct. It allows you to declare pointers or references to a type, but you can't use them in any way that needs to know the definition. So, for example, you can have:

class A;  // Forward declaration

class B
{
public: 
  B(); // Constructor

  MyFunc(A* ptr_to_object_of_type_a);  // Only using a pointer to A

private:

  A* m_another_pointer_to_object_of_type_a;  // Only using a pointer to A
};

But you can't have:

class A;  // Forward declaration

class B
{
public: 
  B(); // Constructor

  MyFunc(A* ptr_to_object_of_type_a)
  {
    ptr_to_object_of_type_a->AnotherFunc();  // Attempting to dereference the pointer to call a method
  }

private:

  A m_object_of_type_a;  // Declaring an object of type A 

In the second version, you'd have to include the full definition of A, most likely from a header file.

What your error message means is that in /usr/local/oce-0.9.1/include/oce/Handle_StlMesh_Mesh.hxx, which you've included, there is a forward declaration to the structure StlMesh_Mesh, but somewhere in your code, there's something that needs to know the full definition of it, and you haven't included the header file that contains that full definition.

[game]

Thank you very much Mikeyboy,

Thank you very much for nice and clear explanation, You helped me out!

Using your comment, i solved the problem adding #include <StlMesh_Mesh.hxx> header file!

Working,, thank you once again

Game