Hi, I'm new to C++ and I'm having trouble with this dang linker error. The full error is as follows:

Error 4 error LNK2001: unresolved external symbol "public: static class std::list<class Node,class std::allocator<class Node> > NodeManager::node_list" (?node_list@NodeManager@@2V?$list@VNode@@V?$allocator@VNode@@@std@@@std@@A) Nodes.obj

Error 5 fatal error LNK1120: 1 unresolved externals

From this error, I have deduced that the problem is with NodeManager::node_list. After doing a little researching, I have found that LNK2001 refers to an undefined object, right? I do define node_list as a static member of NodeManager, so I'm not quite sure what's wrong.

Here's some code (I cut it short for brevity's sake):

Node.h

#ifndef NODES_H
#define NODES_H

#include <vector>
#include <list>

class Node {
public:
	std::vector<int> children;

	Node(int num, float x, float y, float z) {
		num_ = num;
		x_ = x;
		y_ = y;
		z_ = z;
	}

private:
	int num_;
	float x_;
	float y_;
	float z_;
};

class NodeManager {
public:
	static std::list<Node> node_list;
};

void generateNodes();

#endif

Node.cpp

#include "Nodes.h"

#include <list>

void generateNodes() {
	Node n1(1, 346.0, 26.5, -470.0);
	n1.children.push_back(2);
	n1.children.push_back(4);
	n1.children.push_back(5);
	NodeManager::node_list.push_back(n1);

	// defining more nodes
}

The only reason I created a NodeManager class is because I need a list to keep track of my node list, and I was told that you cannot create, for example, a list of Node's within the Node definition. Is this correct?

Any ideas? Also, feel free to provide constructive criticism.

Thanks in advance.

static class objects also have to be declared globally in a *.cpp file

// Node.cpp
#include "Nodes.h"

#include <list>

// declare the static object globally
std::list<Node> NodeManager::node_list;

void generateNodes() {
	Node n1(1, 346.0, 26.5, -470.0);
	n1.children.push_back(2);
	n1.children.push_back(4);
	n1.children.push_back(5);
	NodeManager::node_list.push_back(n1);

	// defining more nodes
}

Edited 6 Years Ago by Ancient Dragon: n/a

Wow, thanks for the quick reply. And thanks, that got rid of my errors.

However, is it okay to declare a global list like that if many other files are going to be #include'ing Node.h? Wouldn't that reset its value? That's the reason I was originally trying to do a static list.

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