I have created 2 class's and I am trying to get one to point to another one but I am getting this error.



2664: 'main_tree::TreeNode<Item>::set_Data_Link' : cannot convert parameter 1 from 'node<Item>' to 'main_tree::TreeNode<Item> *'
1> with
1> [
1> Item=std::string
1> ]
1> and
1> [
1> Item=user
1> ]
1> and
1> [
1> Item=std::string
1> ]
1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
1> see reference to function template instantiation 'void data_link<std::string,user>(main_tree::TreeNode<Item> *&,node<user> *)' being compiled
1> with
1> [
1> Item=std::string
1> ]
1>


You should post some code, this error message is not enough to see what is wrong.



template <class Item>

class node
{
public:
typedef Item value_type;

node(const Item& init_data = Item(),node* init_link=NULL)
{data_field = init_data; next = init_link;}

void set_data(const Item& new_data){data_field = new_data;}
void set_next(node* new_link) {next = new_link;}

const Item& data() const{return data_field;}
const node* link() const{return next;}
node* link() {return next;}
Item& data() {return data_field;}
private:
Item data_field;
node *next;
};




template <class Item>

class TreeNode
{
public:
typedef Item value_type;

TreeNode(const Item& init_data = Item(),
TreeNode* init_Left_link=NULL,
TreeNode* init_Right_link=NULL,
TreeNode* init_Data_link=NULL)
{
data_field = init_data;
Data = init_Data_link;
Left = init_Left_link;
Right = init_Right_link;
}

void set_data(const Item& new_data){data_field = new_data;}
void set_Data_Link(TreeNode* new_link) {Data = new_link;}
void set_Left_Link(TreeNode* new_left) {Left = new_left;}
void set_Right_Link(TreeNode* new_right) {Right = new_right;}

const TreeNode* Data_link() const{return Data;}
const TreeNode* Left_link() const{return Left;}
const TreeNode* Right_link() const{return Right;}
const Item& data() const{return data_field;}

bool is_leaf() const{return (Left == NULL)&&(Right == NULL);}

TreeNode*& Data_link() {return Data;}
TreeNode*& Left_link() {return Left;}
TreeNode*& Right_link() {return Right;}
Item& data() {return data_field;}

private:
Item data_field;
TreeNode *Left;
TreeNode *Right;
TreeNode *Data;
};




template <class Item, class Item2>
void data_link(TreeNode<Item> *&root,node<Item2>* head_ptr)
{


data_link(root->Left_link(),head_ptr);

while(head_ptr)
{
if(root->data() == head_ptr->data().name)
{
root->set_Data_Link();
}
}
data_link(root->Right_link(),head_ptr);

}


I am trying to link the link list to the tree

Post the real code. In your data_link method you're calling root->set_Data_Link which takes no argument while in the code snippet above the set_Data_Link does have one argument.

The error message indicates that you're passing the wrong node type to set_Data_Link (node<Item> instead of TreeNode<Item>).

I removed the argument this is what it should say [color="#1C2837"][font="CourierNew, monospace"][color="#000000"]root[color="#666600"]->[color="#000000"]set_Data_Link[color="#666600"]([color="#000000"]head_ptr[/font][color="#666600"][font="CourierNew, monospace"]);[/font]
[font="CourierNew, monospace"][color="#666600"]but [/font][color="#1C2837"][font="CourierNew, monospace"][color="#000088"]void[color="#000000"] set_Data_Link[color="#666600"]([color="#660066"]TreeNode[color="#666600"]*[color="#000000"] new_link[color="#666600"]) [color="#666600"]{[color="#660066"]Data [color="#666600"]=[color="#000000"] new_link[color="#666600"];} [/font]
[color="#1C2837"][font="CourierNew, monospace"][color="#666600"]takes a treeNode as an argument so I need to make the TreeNode a template so it can take any type but note sure how.[/font]
[color="#666600"][font="CourierNew, monospace"] [/font]
[color="#666600"][font="CourierNew, monospace"]and what do you mean by real code? This is my real code.[/font]

the main after the loading of both the tree and the link list.

I figured out how to get it to work I had to add another item to the template

[font=CourierNew, monospace][size=2][color=#000000] [color=#000088]void[color=#000000] set_Data_Link[color=#666600]([color="#660066"]Item2[color=#666600]*[color=#000000] new_link[color=#666600])[color=#000000] [color=#666600]{[color=#660066]Data[color=#000000] [color=#666600]=[color=#000000] new_link[color=#666600];}[/font]
[font=CourierNew, monospace][size=2][color=#666600]
[/font]
[font=CourierNew, monospace][size=2][color=#666600]instead of [/font]
[font=CourierNew, monospace][size=2][color=#666600]
[/font]
[font=CourierNew, monospace][size=2][color=#666600][color=#1C2837][font=arial, verdana, tahoma, sans-serif][color=#000000] [color=#000088]void[color=#000000] set_Data_Link[color=#666600]([color=#660066]TreeNode[color=#666600]*[color=#000000] new_link[color=#666600])[color=#000000] [color=#666600]{[color=#660066]Data[color=#000000] [color=#666600]=[color=#000000] new_link[color=#666600];}[/font][/font]