C++ Homework - Binary Search Tree Help

Question

For starters this is homework, I just really need help with a binary search tree.

The program is to display polymorphism, using person as an abstract base class, and other types of people which inherit Person. Each person has a last name, and I am trying to use a binary search tree to alphabetize the people by last name.

I have written what I think should be an acceptable Binary Search Tree, But I am still getting errors. The binary search tree only needs to have an insert and traverse function. Which should be recursive.

The error I am getting is: Error 19 error C4430: missing type specifier - int assumed bst.cpp

This occurs at line 51, 64 and 70. Here is my code:

Header File:

#ifndef BST_H
#define BST_H

template <class T>
class BST
{
    private:
        class BinNode
        {
            public:
                BinNode(void);
                BinNode(T node);

                BinNode *left;
                BinNode *right;
                T data;
        };

        BinNode* root;

    public:
        BST();   
        ~BST();

        void insert(const T &);
        void traverse();
        void visit(BinNode *);


    //Utlity Functions
    private:
        void insertAux(BinNode* &, BinNode *);
        void traverseAux(BinNode *, ostream &);
};

#include "BST.cpp"
#endif

Implementation File:

 #include <iostream>
#include <string>

using namespace std;

#ifdef BST_H

template <class T>
BST<T>::BinNode::BinNode()
{
    left = right = 0;
}

template <class T>
BST<T>::BinNode::BinNode(T node)
{
   left = right = 0;
   data = node;
}

template <class T>
BST<T>::BST()
{
    root = 0;
}

template <class T>
void BST<T>::insertAux(T i, BinNode* &subRoot)
{
    //inserts into empty tree
    if(subRoot == 0)
        subRoot = new BinNode(i);
    //less then the node
    else if(i<subRoot->data)
        insertAux(i, subRoot->left);
    //greater then node
    else
        insertAux(i, subRoot->right);
}

template <class T>
void BST<T>::insert(const T &i)
{
    insertAux(T i, root)
}

template <class T>
BST<T>::traverse()
{
    traverseAux(root);
}

template <class T>
BST<T>::traverseAux(BinNode *subRoot)
{
    if (subRoot == 0)
        return;
    else
    {
        traverseAux(subRoot->left);
        visit(subRoot);
        traverseAux(subRoot->right);
    }       
}

template <class T>
BST<T>::visit(BinNode *b)
{
    cout << b->data << endl;
}

#endif

If anyone could take a quick glance at this for me and give me some tips? It is really confusing me right now. Thanks!

Please clearly indicate the line(s) on which you're getting errors. Don't make us count. — Greg Hewgill
– Greg Hewgill, Commented Dec 6, 2010 at 0:29

Charles Salvia · Accepted Answer · 2010-12-06 00:27:04Z

3

You omitted the return type on some of your function definitions.

For example:

template <class T>
BST<T>::traverse()
{
    traverseAux(root);
}

should be:

template <class T>
void BST<T>::traverse()
{
    traverseAux(root);
}

answered Dec 6, 2010 at 0:27

Charles Salvia

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Comments

Caner · Accepted Answer · 2010-12-06 00:27:23Z

1

You should change BST<T>::traverse() to void BST<T>::traverse()

Similar with other erros.

answered Dec 6, 2010 at 0:27

Caner

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