🚀 go-pugleaf

Hi all.  

I have been working on a homework problem in and I have received
several errors, well actually the same error in three places.  I am
using GNU 2.7.2 under OS/2.

The error is: 
tstbinary_node.cpp:42: sorry, not implemented: use of `var_decl' in
function template.

Now I did get it to compile and execute with the correct results,
however, I am not sure if what I did was what the professor wanted. 
What I changed to get it to work is line 42 to read
"preorder(root,cout)" and line 75 to "void preorder(binary_node<T>
*p, ostream& os)".  The program is for binary trees.

I do hope that someone can give me tell me if this just will not
work as the professor has requested it to, and why, or if I just did
something incorrect in the code.


My code looks like:  ( I removed some lines to shorten the post).
--------------------------------------------------
The main program (tstbinary_node)

#include <iostream.h>
#include <cstdlib>
#include "binary_node.h" //..... This is what I wrote.

int main(){
  binary_node<int> *root = NULL;
  int n;
  cout << "\nInsert them: ";
  while(cin >> n) {
      bst_insert(root, n);
  }
  cout << "\nPreorder:" << endl;
  preorder(root);	// This is line 42 Error here................

  return EXIT_SUCCESS;
}

--------------- binary_node.h----------------
template <class T>
class binary_node {
   public:
      binary_node *left, *right;
      T data;

      // Constructors
      binary_node() : left(0), right(0), data(T()) {}
      binary_node(const T& n) : left(0), right(0), data(n) {}
};
//==================================================================
===
template <class T>
void bst_insert(binary_node<T>*& p, const T& n){
   if (!p) {   // Root node?
      p = new binary_node<T>(n);
   }
   else {   
      if (p->data > n) {
         if ( p->left != NULL)            // More nodes to the left?
            bst_insert(p->left, n);
         else                             // Insert node here.
            p->left = new binary_node<T>(n);
      } else if (p->data < n) {
         if ( p->right != NULL)           // More nodes to the
right?
            bst_insert(p->right, n);
         else                             // Insert node here.
            p->right = new binary_node<T>(n);
      } // if (p->data == n) is just ignored!
   }
   return;
}

template <class T>
void preorder(binary_node<T> *p, ostream& os=cout) { // This is line
75....
   if (p!=NULL) {
      cout << p->data << endl;
      preorder(p->left, cout);
      preorder(p->right, cout);
   }
   return;
}

---------------------------------------------------
Jon Santarelli

jsant@interaccess.com
http://homepage.interaccess.com/~jsant