C++ :: Linked List Set Function - Forbids Comparison Between Pointer And Integer

I'm trying to write a function called 'set' that sets the value of the i'th cell to val on my linkedList, and then returns the previous contents. I am stuck on it due to compiling errors:

This is my Node struct:

#ifndef NODE_H
#define NODE_H
#include <iostream>
template <typename T>
struct Node {
friend std::ostream &operator <<(std::ostream &os, const Node<T> &node) {

[Code] ....

The following is my set function:

template <typename T>
T set(Node<T> *head, int i, const T &val) {
for(int n = 0; n < i; n++)
if(head == val) {
val = i;
} return val;
} #endif

When I try to call it in the main() I get these errors:

node_utils.h: In function ‘T set(Node<T>*, int, const T&) [with T = int]’:
node_demo.cpp:26:38: instantiated from here
node_utils.h:161:2: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
node_utils.h:162:3: error: assignment of read-only reference ‘val’

So, I understand that I can't compare head & val on my if-statement -- But what do I do?