// ptr2.cpp
// tom bailey  27 aug 08

// Simple use of pointers to form a linked list.
// C-style, uses global functions instead of class methods.

#include <iostream>
using std::cout;
using std::endl;
using std::cin;

// A struct is a class with public default.
struct Node {
	Node * next;
	// Construct a Node that references *theNext.
	Node( Node * theNext ) {
		next = theNext;
	}
};

// Add a new Node to the beginning of the list referenced
// by ptr.
void addFirst( Node * & ptr ) {
	ptr = new Node( ptr );
}

// Add a new Node to the end of the list referenced by ptr.
void addLast( Node * & ptr ) {
	if( ptr == NULL ) {
		addFirst( ptr );
	}
	else {
		Node * curr = ptr;
		Node * next = curr->next;
		while( next != NULL ) {
			curr = next;
			next = curr->next;
		}
		addFirst( curr->next );
	}
}

// Print the addresses of the Nodes of the list referenced
// by ptr.
void printList( Node * ptr ) {
	if( ptr != NULL ) {
		cout <<  ptr << endl;
		printList( ptr->next );
	}
}

// Return the number of Nodes in the list referenced by ptr.
int listLength( Node * ptr ) {
	int length = 0;
	while( ptr != NULL ) {
		++length;
		ptr = ptr->next;
	}
	return length;
}

// Destroy all the Nodes in the list referenced by ptr.
void destroyList( Node * & ptr ) {
	while( ptr != NULL ) {
		Node * curr = ptr;
		ptr = ptr->next;
		delete curr;
	}
}

int main() {
	Node * start = NULL;
	cout << "list is" << endl;
	printList( start );
	cout << "end of list" << endl << endl;

	addLast( start );
	cout << "list is" << endl;
	printList( start );
	cout << "end of list" << endl << endl;

	for( int i=0; i<4; ++i ) {
		addFirst( start );
	}
	cout << "list is" << endl;
	printList( start );
	cout << "end of list" << endl << endl;

	for( int i=0; i<4; ++i ) {
		addLast( start );
	}
	cout << "list is" << endl;
	printList( start );
	cout << "end of list" << endl << endl;

	cout << "list length is " << listLength( start ) << endl;

	cout << "How many more? ";
	int n = 0;
	cin >> n;

	for( int i=0; i<n; ++i ) {
		addLast( start );
	}

	cout << "list length is " << listLength( start ) << endl;

	destroyList( start );

	cout << "list length is " << listLength( start ) << endl;

	return 0;
}