c++ binary trees... compile trouble

[TMS]

I'm trying to write an address book that is based on a binary tree. I'm devloping in Visual C++ (I blew up my Ubuntu with the new dist, so no EMACS), starting with the basics:

#ifndef binarySearchTree_h
#define binarySearchTree_h
 
#include <string>
#include <iostream>
 
using namespace std;
 
//Define the node
struct treeNode
//An object of type TreeNode 
{
    string data;
    struct node* left;
    struct node* right;
 
treeNode(string str)
//constructor: Make a node containing str.
{
    data = str;
    left = NULL;
    right = NULL;
}
 
};
 
//define the class
class binarySearchTree
{
public:
    binarySearchTree(); 
        //constructor
    bool isEmpty() const;
                 //
    bool treeContains(treeNode *root, string data);
        //return true if item is one of the items in the 
        //binary sort tree to which root points. Return
        //false if not
 
 
protected:
    treeNode *root;
 
};
#endif
 

my problem is in the implementation file in the treecontains() function:

#include "binarySearchTree.h"
 
#include <string>
#include <iostream>
 
using namespace std;
 
binarySearchTree::binarySearchTree() :root(NULL)
{
}
bool binarySearchTree::isEmpty() const
        //return true if tree is empty
{
    return (root == NULL);
}
bool binarySearchTree::treeContains(treeNode *root, string data)     
        //return true if item is one of the items in the 
        //binary sort tree to which root points. Return
        //false if not
    {
        if(root==NULL)
            //tree is empty
        {
                return false;
        }
        if(data==root->data)
            //item has been found
        {
            return true;
        }
 
 
        if(data < root->data)
            //item is in left subtree
        {
            return treeContains(root->left, data);  //error
        }
        else
            //item is in right subtree
        {
            return treeContains(root->right, data); //error
        } 
 
    } //end treeContains()
 
 

I get an error that says:

Compiling...
test.cpp
binarySearchTree.cpp
c:\program files\microsoft visual studio\myprojects\binaryaddressbook\binarysearchtr ee.cpp(41) : error C2664: 'treeContains' : cannot convert parameter 1 from 'struct node *' to 'struct treeNode *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
c:\program files\microsoft visual studio\myprojects\binaryaddressbook\binarysearchtr ee.cpp(46) : error C2664: 'treeContains' : cannot convert parameter 1 from 'struct node *' to 'struct treeNode *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
Error executing cl.exe.

binaryAddressBook.exe - 2 error(s), 0 warning(s)

Here is my test file:

#include "binarySearchTree.h"
 
#include <iostream>
 
using namespace std;
 
int main()
{
 
    treeNode *root;  //pointer to the root noode in the tree
    root = NULL;  //start with an empty tree
 
 
 
    return 0;
}
 

as you can see main doesn't do anything yet, but get the constructors working.

please help so I can get this thing going?

thank you

[Banfa]

Is this structure correct?

//Define the node
struct treeNode
//An object of type TreeNode 
{
    string data;
    struct node* left;
    struct node* right;
 
    treeNode(string str)
    //constructor: Make a node containing str.
    {
        data = str;
        left = NULL;
        right = NULL;
    }
};
 

?

Particularly is struct node* left; right or should it be struct TreeNode * left; ?

If it is correct where is struct node defined?