[Libmesh-users] May be a simple problem?!?

[Jens O. <oe...@st...>]

Hi,

I've written a direct current modelling program for geophysical purposes
with libmesh. Till now every thing seems to work quit proper. So far so
good.

But now to my problem, which is quit simple so I think, but I could not
solve it. I have data associated to each node. Now I would like to
create a vector of nodes, in which the nodes marked as a electrode
position are stored (the marker is -99). To solve this I've done the
following:

const Mesh& const_mesh = mesh;
		
std::vector<Number> node_data;
std::vector<Node> ElectrPos;
unsigned int ElectrCount=1;

unsigned int n_nodes = mesh.n_nodes();
		
for (unsigned int n_cnt=0; n_cnt<n_nodes; n_cnt++)
{
	const Node& curr_node = const_mesh.node(n_cnt);
	const Node* curr_node_ptr = const_mesh.node_ptr(n_cnt);

	if (mesh.data.has_data (curr_node_ptr))
	{
		node_data = mesh.data.get_data (curr_node_ptr);
		if (node_data[0]==-99)
		{
			ElectrPos.resize(ElectrCount);
			ElectrPos.push_back(curr_node);
			ElectrCount++;
		}
	}
}

The problem is, that it's not possible to resize the vector ElectrPos.
The compiler complains:
/usr/include/c++/3.3/bits/stl_vector.h: In member function `void 
   std::vector<_Tp, _Alloc>::resize(unsigned int) [with _Tp = Node,
_Alloc =    std::allocator<Node>]':
InOut.C:163:   instantiated from here
/usr/include/c++/3.3/bits/stl_vector.h:452: error: no matching function
for    call to `Node::Node()'
/home/oeser/DA/libmesh/include/node.h:150: error: candidates are: 
   Node::Node(const Point&, unsigned int = DofObject::invalid_id)
/home/oeser/DA/libmesh/include/node.h:139: error:                 
   Node::Node(const Node&)
/home/oeser/DA/libmesh/include/node.h:130: error:                 
   Node::Node(double, double, double, unsigned int)

If I change ElectrPos.resize(ElectrCount) to
ElectrPos.resize(curr_node) as the compiler mentioned (with absence of
understanding why I should do this), the compiler complains:
InOut.C:163: error: no matching function for call to `std::vector<Node, 
   std::allocator<Node> >::resize(const Node&)'
/usr/include/c++/3.3/bits/stl_vector.h:434: error: candidates are: void 
   std::vector<_Tp, _Alloc>::resize(unsigned int, const _Tp&) [with _Tp
= Node,    _Alloc = std::allocator<Node>]
/usr/include/c++/3.3/bits/stl_vector.h:452: error:                 void 
   std::vector<_Tp, _Alloc>::resize(unsigned int) [with _Tp = Node,
_Alloc =    std::allocator<Node>]

What's going on, where is the problem? Because I'm currently new to OOP
and C++ I could not solve the problem. But I hope you can give me some
hints or a other way to solve the problem.

I think I need to store the reference, because I need to call
DofObject::dof_number for these nodes.

Best regards.
Jens.

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