I've got a program to do for a class I'm taking. I've got most the code written but I can't get the two classes to play together like I want them to.

Here is the relavent part of the assignment:

A concordance is an alphabetical listing of all words in a text
with a list associated with each word of the line numbers in which the
word appears

Design and implement two C++ classes for linked lists (see below).

Design, code and test a C++ program using the linked lists that
reads a text file (using file redirection) and generates a concordance of
all the words from that text.

You will need a linked list of strings and linked list of numbers, Each
node of the string list must point to a list of numbers.

One class, wordlist, uses the other class numlist to keep a list of line numbers in which a certain word was found. When I test both classes alone, they work as I think they should, but when I try to use numlist called from wordlist, it only remembers the first line number inserted when you put the same word in.

wordlist.h

#ifndef linkdlst_h 
#include <iostream>
#include <string>
/* HUGELY IMPORTANT NOTE:
 *
 * This class is dependant upon the other node class!  It will fail without it! */
#include "numlist.h"


using namespace std;

class concordance
  {
	private:
		
	  struct node
		{
		  string data;
			numlist line_nums;
			node *next;
		};
		node *list_head;
		

	
	// Methods
	  bool is_before(string list_data, string data);
		bool is_same(string list_data, string data);
		bool is_after(string list_data, string data);
		//Note: is_first is implied--it's a one line thing
		string tolowercase(string str);
		
	public:
		concordance();
		~concordance();
		
		void append(string data, int n);
		void insert(string data, int n);
		void print();
	};

#define linkdlst_h
#endif

Exert from wordlist.cpp (I didn't include the private functions such as touppercase and is_same--they work.)

concordance::concordance()
  {
	list_head = NULL;
	}
	
concordance::~concordance()
  { //The destructor may have to do something here.
	node *previous;
	node *current;
	previous = current = list_head;
	while (current != NULL) //Delete each item in the list.
	  {
		current = previous -> next;
 		previous -> line_nums.~numlist();
		delete previous;
		previous = current;
		}
	previous = current = list_head = NULL;
	}

void concordance::insert(string data, int n)
  {
	node* current = list_head;
	node* previous = list_head;
	node* newnode = NULL;
	bool done = false; // After the loop has executed, exit it.
	
	// Create a node to insert the data into
	newnode = new(node);
	newnode -> data = data;
	newnode -> line_nums.append(n);
			
	// Build the list by inserting data in an organized manner.
	if (list_head != NULL)
	  {
		while (done == false)
		  {
			if (is_before(current -> data, data))
				{ //Insert into the list
				newnode -> next = previous -> next;
				previous -> next= newnode;
				done = true;
				}
			else if (is_same(current -> data, data))
			  {
// cout << "is_same ";				
				//Append line number to line number list
 				newnode -> line_nums.append(n);
				done = true;
				}
			else
				{ //if !is_before and !is_same, it must be is_after.
		 		if (current -> next == NULL)
					{
				  //The end of list has been reached.
					//Insert at the end
					newnode -> next = NULL;
					current -> next = newnode;
					done = true;
					}
				else
				  {
					previous = current;
					current = current -> next;
					done = false;
					}
				}
			}
		}
		else
	  {
		newnode -> next = NULL;
		list_head = newnode;
		}
	}
void concordance::print()
  {
	node *current;
  current = list_head;
	while (current != NULL)
	  {
	  cout << current -> data << " <- data | position -> ";
  	current -> line_nums.print();
		cout << endl;
	  current = current -> next;
	  }
	}

numlist.h

/* Source: Program 0, Assignment 7. */
#ifndef numlist_h 
#include <iostream>

using namespace std;

class numlist
  {
	private:
	  struct node
		{
		  int data;
			node *next;
		};
		node *list;
	
	public:
    typedef node *node_ptr;
		numlist();
		~numlist();
		bool defined;
		
		void append(int n);
		void print();

	};
		
#define numlist_h
#endif

numlist.cpp

#include "numlist.h"

numlist::numlist()
  {
	list = NULL;
  }

numlist::~numlist()
  { //The destructor may have to do something here.
	node *previous;
	node *current;
	previous = current = list;
	while (current != NULL) //Delete each item in the list.
	  {
		current = previous -> next;
		delete previous;
		previous = current;
		}
	previous = current = list = NULL;
	}


void numlist::append(int str)
  {
	node *current;
	node *newnode;
	current = newnode = NULL;

  //Create a new node to put the data in.
	newnode = new(node);
	newnode -> data = str;
	newnode -> next = NULL;

cout << " List Head: " << list << " Current: " << current << endl;		
	//Decide where to put it.	
	if (current == NULL) //Then this is an empty list.
	  {
		list = newnode;
		}
	else //Find the end of the list
	  {
		while (current -> next != NULL)
		  {
			current = current -> next;
			}
cout << " List Head: " << list << " Current: " << current << endl;		
		current -> next = newnode;
		}
//		print();
  }
		

void numlist::print()
  {
	node *current;
  current = list;
	while (current != NULL)
	  {
	  cout << current -> data << " ";
	  current = current -> next;
	  }
	}

My test program for wordlist.cpp simply asks for input (cin) and uses the insert procedure to add data to the list.

The test program for numlist.cpp just adds a bunch of data and prints out the list.

Thanks for any suggestions you have. I'm out of ideas here.

This is a c++ program -- why are you wrinting your own linked lists instead of using STL <list> classes?

With the exception of string functions, use of the STL is not allowed in that class.

I was not able to get this to work properly before the due date. For some reason the program sets the pointer to the linked list of numbers to null if I call the insert procedure with anything other than what I had called it before.

This works:
insert("Hey", 3)
insert("Hey", 4)

Output:
Hey 3 4

This doesn't:
insert("Hey", 3)
insert("Hi", 4)

Hey [null]
Hi 4