Problem with pointers

Can't get my pointers working. I have head = tmp only when head = NULL, which loads the first piece of data from the file. But when the while loop finishes, head->key now contains the last piece of data in the file. How is the contents of head changing?

URL

void updateindex() {
int ordNo;
ordNo = 0;
ifstream inputPathway;
inputPathway.open("orderfile.txt", ios::in);
if (!inputPathway.is_open() ) {
cout << "No orderfile present. A new one will be constructed.\n\n"; // checks if file exists to
return; // prevent infinite loop
} //

Link tmp;
tmp = new index;
inputPathway.read(reinterpret_cast<char*> (&order1), sizeof(order));
while (!inputPathway.eof()) { // build binary tree index here
strcpy(tmp->key,order1.name);
tmp->recordnum = order1.ordernum;
tmp->left = NULL;
tmp->right = NULL;
if (head == NULL) { // first node in a new index is placed at head
head = tmp;cout << head->key << " has been put at head"; }
inputPathway.read(reinterpret_cast<char*> (&order1), sizeof(order));
ordNo++;
ordertotal = order1.ordernum;
}
cout << "\nThere are " << ordNo << " orders on record\n";
inputPathway.close();
cout << head->key << " is now at head";

Someone pointed out that I had left the creation of tmp outside of the while loop, so head was just pointing to the first instance.

Disaster averted!