Sorted List as a Linked Structure error

[sethman410]

I copied this code from the book by Nell Dale. "C++ Plus Data Structures"

Here is my Sorted header/implementation file.

#ifndef SORTED_H
#define SORTED_H
#include "ItemType.h"
#include <new> // std::bad_alloc

class SortedType
{
public:
	SortedType();
	~SortedType();

	bool isFull() const;
	int GetLength() const;
	void MakeEmpty();
	ItemType GetItem(ItemType item, bool& found);
	void PutItem(ItemType item);
	void DeleteItem(ItemType item);
	void ResetList();
	ItemType GetNextItem();
private:
	NodeType* listData;
	int length;
	NodeType* currentPos;
};
struct NodeType
{
	ItemType info;
	NodeType* next;
};

SortedType::SortedType()
{
	length = 0;
	listData = NULL;
}
bool SortedType::isFull() const
{
  NodeType* location;
  try
  {
	  location = new NodeType;
	  delete location;
	  return false;
  }
  catch(std::bad_alloc exception)
  {
	  return true;
  }
}
int SortedType::GetLength() const
{
	return length;
}
void SortedType::MakeEmpty()
{
	NodeType* tempPtr;
	while (listData != NULL)
	{
		tempPtr = listData;
		listData = listData->next;
		delete tempPtr;
	}
	length = 0;
}

ItemType SortedType::GetItem(ItemType item, bool& found)
{
	bool moreToSearch;
	NodeType* location;

	location = listData;
	found = false;
	moreToSearch = (location != NULL);

	while (moreToSearch && !found)
	{
		switch(item.ComparedTo(location->info))
		{
		case GREATER: location = location->next;
					  moreToSearch = (location != NULL);
					  break;
		case EQUAL:	  found = true;
					  item = location->info;
					  break;
		case LESS:    moreToSearch = false;
					  break;
		}
	}
	return item;
}
void SortedType::PutItem(ItemType item)
{
	NodeType* newNode;			// Pointer to node being inserted
	NodeType* predLoc;			// Trailing pointer
	NodeType* location;			// traveling pointer
	bool moreToSearch;

	location = listData;
	predLoc = NULL;
	moreToSearch = (location != NULL);
	// Find insertion point.
	while (moreToSearch)
	{
		switch (item.ComparedTo(location->info))
		{
		case GREATER: predLoc = location;
					  location = location->next;
					  moreToSearch = (location != NULL);
					  break;
		case LESS:	  moreToSearch = false;
					  break;
		}
	}

	// Prepare node for insertion.
	newNode = new NodeType;
	newNode->info = item;

	// Insert node into list.
	if (predLoc == NULL)			// Insert as first.
	{
		newNode->next = listData;
		listData = newNode;
	}
	else
	{
		newNode->next = location;
		predLoc->next = newNode;
	}
	length++;
}
void SortedType::DeleteItem(ItemType item)
{
	NodeType* location = listData;
	NodeType* tempLocation;

	// Locate node to be deleted.
	if (item.ComparedTo(listData->info) == EQUAL)
	{
		tempLocation = location;
		listData = listData->next;		// Delete first node.
	}
	else
	{
		while ((item.ComparedTo(location->next)->info) != EQUAL)
			location = location->next;

		// Delete node at location->next
		tempLocation = location->next;
		location->next = (location->next)->next;
	}
	delete tempLocation;
	length--;
}

void SortedType::ResetList()
	// Post: currentPos has been initialized.
{
	currentPos = NULL;
}
ItemType SortedType::GetNextItem()
{
	ItemType item;
	if (currentPos == NULL)
		currentPos = listData;
	item = currentPos->info;
	currentPos = currentPos->next;
	return item;
}

SortedType::~SortedType()
{
	NodeType* tempPtr;

	while (listData != NULL)
	{
		tempPtr = listData;
		listData = listData->next;
		delete tempPtr;
	}
}
#endif 

Here is the ItemType header/implementation file.

#ifndef ITEMTYPE_H
#define ITEMTYPE_H
#include <fstream>

const int MAX_ITEMS = 5;
enum RelationType {LESS, GREATER, EQUAL};

class ItemType
{
public:
	ItemType();
	RelationType ComparedTo(ItemType) const;
	void Print(std::ofstream&) const;
	void Initialize(int number);
private:
	int value;
};
ItemType::ItemType()
{
	value = 0;
}

RelationType ItemType::ComparedTo(ItemType otherItem) const
{
	if (value < otherItem.value)
		return LESS;
	else if (value > otherItem.value)
		return GREATER;
	else return EQUAL;
}

void ItemType::Initialize(int number)
{
	value = number;
}

void ItemType::Print(std::ofstream& out) const
	// Pre: out has been opeend.
	// Post: value has been sent to the stream out.
{
	out << value << " ";
}
#endif 

The error is at line 145 in sorted file. Both item and location are underlined in red. For item it says expression must have pointer type. For location it says "no suitable constructor exists to convert from "NodeType*" to "ItemType".

Any ideas why?

[coder777]

Any ideas why?

The ) is at the wrong place:

		while ((item.ComparedTo(location->next)->info)) != EQUAL)
			location = location->next;

By the way: the loop will certainly lead to a crash. What happens when location or location->next is NULL before EQUAL?