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[Yellowhottub]

I am unable to get this to compile do to a symbol referencing error. As far as I know it is a problem with the outputting print functions.

Header File:

#ifndef BST_H
#define	BST_H

#include <iostream>
#include <cstdlib>

const int MAX = 8;
typedef char Word[MAX+1];	

class BST
{
	//friend function
	friend std::ostream& operator << (std::ostream& out_s, const BST &t);

	private:
	    struct Node
	    {
		Word data;
		int count;
		Node *left;
		Node *right;
	    };
		Node *root;

	    //helper functions
	    void destroy(Node *r);
	    int find_length(Node *r);
	    void help_remove(Node *&t, Word target);
	    void remove_node(Node *&t);
	    int find_count(Node *&t, Word target);
	    void help_print(std::ostream &out_s, Node *r);

	public:
	    //constructor
	    BST();
	    //destructor
	    ~BST();
	    //modification member functions
	    int length();
	    void insert(Word entry, int count);
	    void remove(Word target);	
	    void print(std::ostream &out_s);
};

#endif

Implementation File:

#include "BST.h"
#include <iostream>
#include <cstring>
#include <iomanip>
using namespace std;


BST:: BST()
{
	root = NULL;
}

BST:: ~BST()
{
	destroy(root);
}

void BST:: destroy(Node *r)
{
	if(r != NULL)
	{
	    destroy(r -> left);
	    destroy(r -> right);
	    delete r;
	}

}

int BST:: find_length(Node* r)
{
	if(r != NULL)
	    return 0;
	else
	    return find_length(r -> left) + 1 + find_length(r -> right);
}

void BST:: help_remove(Node *&t, Word target)
{
	if(t -> data == target)
	    remove_node(t);
	else if(strcmp(t -> data, target) > 0)
	    help_remove(t -> left, target);
	else
	    help_remove(t -> right, target);
}

void BST:: remove_node(Node *&t)
{
	Node *back, *ptr;
	
	if(t -> left == NULL && t -> right == NULL)
	{
	    delete t;
	    t = NULL;
	}
	else if(t -> left == NULL)
	{
	    ptr = t;
	    t = t -> right;
	    delete ptr;
	}
	else if(t -> right == NULL)
	{
	    ptr = t;
	    t = t -> left;
	    delete ptr;
	}
	else
	{
	    back = t;
	    ptr = t -> right;
	    while(ptr -> left != NULL)
	    {
		back = ptr;
		ptr = ptr -> left;
	    }

	    strcpy(t -> data, ptr -> data);
	    
	    if(back == t)
		remove_node(back -> right);
	    else
		remove_node(back -> left);
	}
}

int BST:: find_count(Node *&t, Word target)
{
	if(t -> data == target)
	    return t -> count;
	else if(strcmp(t -> data, target) > 0)
	    find_count(t -> left, target);
	else
	    find_count(t -> right, target);
}

void BST:: help_print(ostream &out_s, Node *r)
{
	if(r != NULL)
	{
	    help_print(out_s, r -> left);
	    cout << r -> data << "                " << r -> count << endl;
	    help_print(out_s, r -> right);
	}
}

int BST:: length()
{
	return find_length(root);
}

void BST:: remove(Word target)
{
	help_remove(root, target);
}

void BST:: insert(Word entry, int count)
{
	Node *back, *ptr, *temp;

	ptr = root;
	back = NULL;

	while(ptr != NULL)
	{
	    back = ptr;
	    if(strcmp(ptr -> data, entry) > 0)
		ptr = ptr -> left;
	    else
		ptr = ptr -> right;
	}
	
	temp = new Node;
	strcpy(temp -> data, entry);
	temp -> left = NULL;
	temp -> right = NULL;
	
	if(back == NULL)
	    root = temp;
	else if(strcmp(back -> data, entry) > 0)
	    back -> left = temp;
	else
	    back -> right = temp;
}

void BST:: print(ostream& out_s)
{
	help_print(out_s, root);
}

ostream& operator << (ostream &out_s, BST &t)
{
	t.print(out_s);
	return out_s;
}

Client Program:

#include <iostream>
#include <iomanip>
#include <fstream>
#include <cstring>
#include <cctype>
#include "BST.h"
using namespace std;

void read_word(ifstream& in_file, Word& word);
void build_list(ifstream& in_file, Word& word);

int main()
{
	char file_name[100];
	ifstream in_file;
	char array[MAX+1];

	cout << "Enter a file name: "; cin >> file_name;
	
	in_file.open(file_name);

	build_list(in_file, array);

	in_file.close();

	return EXIT_SUCCESS;
}

void read_word(ifstream& in_file, Word& word)
{
	char ch;
	int i = 0;
	in_file.get(ch);
 	
	while(isalpha(ch))
	{
		if(i >= MAX)
		{
		    in_file.get(ch);
		    word[MAX] = '\0';
		    break;
		}
		else
		{
		    ch = toupper(ch);
		    word[i] = ch;
		    i++;
		}

	    in_file.get(ch);

	}
}
	
void build_list(ifstream& in_file, Word& word)
{
	BST t;
	int count = 0;
	int test;

	for(int i = 0; i < MAX+1; i++)
	    word[i] = '\0';

	while(!in_file.eof())
	{
	    read_word(in_file, word);
	    if(isalpha(word[0]))
	        t.insert(word, count);
	    for(int i = 0; i < MAX; i++)
		word[i] = '\0';
	}

	cout << "Word" << "          " << "Count" << endl;
	cout << "--------------------" << endl;
	cout << t;
	cout << "--------------------" << endl;

}

[ne555]

Post the compile message

[Yellowhottub]

Undefined First referenced
Symbol in file
operator<<(std::basic_ostream<char, std::_traits<char> >&, BST &const) /var/tmp/ /cc6IG3ty.o
ld: fatal: symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status

[ne555]

Try to respect the prototype
ostream& operator << (ostream &out_s, const BST &t)