Linked list problem

[Psycho]

I'm having a little problem with my linked list. What am I doing wrong?

Here's the source

#include <string>
#include <iostream>
using namespace std;

class Inventory
{
private:
	typedef struct node
	{
		struct node* next;
		string value;
	};
	node *head;
public:
	Inventory()
	{
		head=NULL;
	}
	void PickUp(string item)
	{
		node* newNode, *nodeMove, *previousNode;
		newNode = new node;
		newNode->value = item;
		if(!head)
		{
			newNode = head;
			newNode->next = NULL; //the debugger says this is the line that messes up.
		}
		else
		{
			nodeMove = head;
		    while (nodeMove != NULL && nodeMove->value < item) 
			{
			    previousNode = nodeMove; 
				nodeMove = nodeMove->next; 
			} 
			if (previousNode == NULL) 
			{ 
				head = newNode; 
				newNode->next = nodeMove; 
			} 
			else 
			{ 
				previousNode->next = newNode; 
				newNode->next = nodeMove; 
			}
		}
	}
	void DisplayInv()
	{
		node *nodeMove; 
		nodeMove = head; 
		while (nodeMove) 
		{ 
			cout << nodeMove->value << endl; 
			nodeMove = nodeMove->next; 
		}
	}
	~Inventory() 
	{ 
		node *nodeMove, *nextNode; 
		nodeMove = head; 
		while (nodeMove != NULL) 
		{ 
			nextNode = nodeMove->next; 
			delete nodeMove; 
			nodeMove = nextNode; 
		} 
	} 

};

void main() 
{
	int choice = 0;
	string Value;
	Inventory List;
	cout << "Test v1.0" << endl;
	cout << "1. Add item." << endl;
	cout << "2. Exit." << endl;
	cin >> choice;
	switch(choice)
	{
	case 1: cout << "Type in the item you want to pick up." << endl;
		cin >> Value;
		List.PickUp(Value);
		List.DisplayInv();
		break;
	case 2: List.~Inventory();
		break;
	}
}

I get an application error that says "The memory could not be 'written' "
Thanks in advance
-Psycho

[Sorensen]

I think

if(!head)
		{
			newNode = head;
			newNode->next = NULL;
		}

should be

if(!head)
		{
			newNode->next = NULL;
                        head = newNode;
			
		}

I haven't read past this so there could be more wrong.

[Psycho]

woo! it works, thanks

it gets annoying when I mess a little thing up like that and I spend so much time on something that's so simple.

[Psycho]

Sorry to bug you guys again, but I'm getting an error at random times when inputting values in my linked list

ERROR:
Run-Time Check Failure #3 - The variable 'previousNode' is being used without being defined.

#include <string>
#include <iostream>
using namespace std;

class Inventory
{
private:
	typedef struct node
	{
		struct node* next;
		string value;
	};
	node *head;
public:
	Inventory()
	{
		head=NULL;
	}
	void PickUp(string item)
	{
		node* newNode, *nodeMove, *previousNode;
		newNode = new node;
		newNode->value = item;
		if(!head)
		{
			head = newNode;
			newNode->next = NULL; 
		}
		else
		{
			nodeMove = head;
		    while (nodeMove != NULL && nodeMove->value < item) 
			{
			    previousNode = nodeMove; 
				nodeMove = nodeMove->next; 
			} 
			if (previousNode == NULL) // this is the first place the debugger says the above mentioned error
			{ 
				head = newNode; 
				newNode->next = nodeMove; 
			} 
			else 
			{ 
				previousNode->next = newNode;  //heres the other place the debugger says the same error. :(
				newNode->next = nodeMove; 
			}
		}
	}
	void DisplayInv()
	{
		node *nodeMove; 
		nodeMove = head; 
		while (nodeMove) 
		{ 
			cout << nodeMove->value << endl; 
			nodeMove = nodeMove->next; 
		}
	}
	~Inventory() 
	{ 
		node *nodeMove, *nextNode; 
		nodeMove = head; 
		while (nodeMove != NULL) 
		{ 
			nextNode = nodeMove->next; 
			delete nodeMove; 
			nodeMove = nextNode; 
		} 
	} 

};

void main() 
{
	int choice = 0;
	string Value;
	Inventory List;
	cout << "Test v1.0" << endl;
	cout << "1. Add item." << endl;
	cout << "2. Exit." << endl;
	cin >> choice;
	switch(choice)
	{
	case 1: cout << "Type in the item you want to pick up." << endl;
		cin >> Value;
		List.PickUp(Value);
		List.DisplayInv();
		break;
	case 2: List.~Inventory();
		break;
	}
}

when running the program I get this error at random times. Sometimes after the user puts in 10 values sometimes when the user puts in 3 values etc. dunno, its weird and I have no clue what I'm doing wrong.