Unresolved externals, code doesn't look like anything is wrong yet won't debug

[robertpires]

I have been staring at this for one hour and do not understand what I'm doing wrong. Debugger is saying I have unresolved externals yet everything looks perfect to me, but of course the computer is never wrong so I must be doing something wrong. The '->setNext', and 'setItem' functions are defined in a 'Node.h' header file provided from my class.

#include <iostream>
#include "Node.h"
using namespace std;

void createMap();

struct city{
	char city_name;
	bool visited;
	Node<char> *adjacent_city;
};

int const MAX=9; //currently the company serves 9 cities
city flightMap[MAX]; // declare a global array for flight map;

int main() {
	createMap();
	return 0;
}

void createMap() {
	Node<char> *D_ptr;
	Node<char> *E_ptr;
	Node<char> *H_ptr;

	flightMap[0].city_name='A';
	flightMap[0].visited=false;
	flightMap[0].adjacent_city=new Node<char>;
	flightMap[0].adjacent_city->setItem('B');
	flightMap[0].adjacent_city->setNext(NULL);

	flightMap[1].city_name='B';
	flightMap[1].visited=false;
	flightMap[1].adjacent_city=NULL;

	flightMap[2].city_name='C';
	flightMap[2].visited=false;
	flightMap[2].adjacent_city=new Node<char>;
	flightMap[2].adjacent_city->setItem('B');
	flightMap[2].adjacent_city->setNext(NULL);
	
	flightMap[3].city_name='D';
	flightMap[3].visited=false;
	flightMap[3].adjacent_city=new Node<char>;
	flightMap[3].adjacent_city->setItem('C');
	D_ptr=new Node<char>;
	D_ptr->setItem('E');
	D_ptr->setNext(NULL);
	flightMap[3].adjacent_city->setNext(D_ptr);
				
	
	flightMap[4].city_name='E';
	flightMap[4].visited=false;
	flightMap[4].adjacent_city=new Node<char>;
	flightMap[4].adjacent_city->setItem('F');
	E_ptr=new Node<char>;
	E_ptr->setItem('H');
	E_ptr->setNext(NULL);
	flightMap[4].adjacent_city->setNext(E_ptr);
				
	flightMap[5].city_name='F';
	flightMap[5].visited=false;
	flightMap[5].adjacent_city=new Node<char>;
	flightMap[5].adjacent_city->setItem('G');
	flightMap[5].adjacent_city->setNext(NULL);

	flightMap[6].city_name='G';
	flightMap[6].adjacent_city=new Node<char>;
	flightMap[6].adjacent_city->setItem('F');
	flightMap[6].adjacent_city->setNext(NULL);

	flightMap[7].city_name='H';
	flightMap[7].visited=false;
	flightMap[7].adjacent_city=new Node<char>;
	flightMap[7].adjacent_city->setItem('E');
	H_ptr=new Node<char>;
	H_ptr->setItem('C');
	H_ptr->setNext(NULL);
	flightMap[7].adjacent_city->setNext(H_ptr);
			
	flightMap[8].city_name='I';
	flightMap[8].visited=false;
	flightMap[8].adjacent_city=NULL;
				
	}

here is the header file, I figured this part is correct since it is a template for the class.

#ifndef _NODE
#define _NODE

template<class ItemType>
class Node
{
private:
	ItemType       item;
	Node<ItemType> *next;
public:
	Node();  //default constructor
	Node(const ItemType &anItem); //none default constructor #1
	Node(const ItemType &anItem, Node<ItemType> *nextPtr); //none default constructor #2
	void setItem(const ItemType &anItem);
	void setNext(Node<ItemType> *nextPtr);
	ItemType getItem() const;
	Node<ItemType> *getNext() const;
};
template<class ItemType>
Node<ItemType>::Node() {
	next=NULL;
}

template<class ItemType>
Node<ItemType>::Node(const ItemType &anItem) {
	item=anItem;
}

template<class ItemType>
Node<ItemType>::Node(const ItemType &anItem,Node<ItemType> *nextPtr) {
	item=anItem;
	next=nextPtr;
}

template<class ItemType>
void Node<ItemType>::setItem(const ItemType &anItem) {
	item=anItem;
}

template<class ItemType>
void Node<ItemType>::setNext(Node<ItemType> *nextPtr) {
	next=nextPtr;
}

template<class ItemType>
ItemType Node<ItemType>::getItem() const {
	return item;
}

template<class ItemType>
Node<ItemType>* Node<ItemType>::getNext() const {
	return next;
}
#endif 

the actual unresolved external errors

#1 - error LNK2019: unresolved external symbol _WinMain@16 referenced in function ___tmainCRTStartup	

#2 - Error	2	error LNK1120: 1 unresolved externals	 

[Parasin]

Usually, unresolved externals are when your function parameters/arguments are missing somewhere.

[Chervil]

What is the code in file "Node.h" ?

[AbstractionAnon]

unresolved externals are when your function parameters/arguments are missing somewhere

That's not correct. The compiler will flag will parameters/arguments that are missing.

Unresolved externals occur when you declare functions but do not implement them.

@OP - You haven't show us the declarations and implementation for your node class.
It would also be helpful if you posted the exact error message you're getting from the linker.

[robertpires]

Thank you all for the comments so far. I've updated the OP with more information so I'd appreciate any help on this. Thanks!

[TheIdeasMan]

_WinMain@16 referenced in function ___tmainCRTStartup

I have a vague idea that, this is do with your project being configured as Windows GUI project as opposed to a console app.

I don't use windows, so I could be completely wrong - it is just I remember this sort of problem being mentioned in the past.

EDIT: Also realise the difference between compiler / linker errors and using a debugger program. At the moment you have linker errors. Debugging allows one to step through a program (which must compiled into an executable first) line by line and watch the values of variables (amongst other things), then deduce where it all went wrong.

[robertpires]

I have a vague idea that, this is do with your project being configured as Windows GUI project as opposed to a console app.

I don't use windows, so I could be completely wrong - it is just I remember this sort of problem being mentioned in the past.

! holy cow this was the problem, I created the project as a windows application vs. console...thanks that definitely solved my problem!!!!