#include <stdlib.h> /* definitions and prototypes for calloc() below */
#include <stdio.h>  /* definitions and prototypes for printf() below */

		/* definition of list item structure */
struct Item_t
{
	double data;
	struct Item_t * next;
};

		/* type "Item" is defined in the header file */
#include "mylist.h"

Item *
makeItem( double data )
{
	Item * item = (Item *)calloc( 1, sizeof( Item ) );

	item->data = data;

	return item;
}

void
freeItems( Item * first )
{
	Item *item = first;

		/* the for loop doesn't work for the free function,
		 * because by the time you look at the item->next member,
		 * item has been freed.  So be a little more careful:
		 */
	while( item != NULL )
	{
		Item *next = item->next;
		free( item ); 
		item = next;
	}
}

void
linkItem( Item * item, Item * next )
{
	item->next = next;
}

void
doActionToItems( const Item * first, ItemAction action )
{
	const Item * item;

	for( item = first; item->next != NULL; item = item->next )
		action( item );
}

static void
printItem( const Item * item )
{
	printf( "item data: %f\n", item->data ); 
}

void
printItems( const Item * first )
{
	doActionToItems( first, printItem );
}