Adding random numbers into a linked-list using loop - c++

Question

I want to add a completely random number into a linked-list, but instead of having all of my code in main, I want to use the object-oriented approach. I have my standard Node class and it's header, and then in main I want a loop that runs through 20 times and then stops adding more. I was given my insert function and how it would be called in main, but I can't seem to get the random numbers to work. I understand that you can't assign an int to a class, but I don't really know how else to incorporate my random number into my function in order to insert it into my list.
Here is my code. Observe the error on line 20 of main. Any insight would be great. Thanks!
Main.cpp
#include <iostream>
#include <iomanip>
#include <time.h>
#include "Node.h"
using namespace std;
int main()
{
srand(time(NULL));
Node link_head;
Node instance;
for (int i = 0; i < 20; i++)
{
int random = rand() % 100;
instance.insert(&link_head, &random);
}
}
Node.h
#include <iostream>
#include <iomanip>
#ifndef NODE_H
#define NODE_H
typedef int ElementType;
class Node
{
public:
Node();
ElementType data;
Node *next;
int insert(Node *, Node *);
};
#endif NODE_H
Node.cpp
#include <iomanip>
#include <iostream>
#include "Node.h"
using namespace std;
Node::Node()
{
this -> data = 0;
this -> next = NULL;
}
int Node::insert(Node *link_head, Node *newNode)
{
Node *current = link_head;
while (true)
{
if(current->next == NULL)
{
current->next = newNode;
break;
}
current = current->next;
}
return 0;
}

Answer 1

You are sending the address of an int to a function requiring a pointer on a Node. Allocate a new node first then send it to the function.
for (int i = 0; i < 20; i++)
{
int random = rand() % 100;
Node* newNode = new Node;
newNode->data = random;
instance.insert(&linkHead, newNode);
}
As stated, insert method should really be static of even a free function since it access only public members of the struct.

Answer 2

Your code is flawed in several ways.
instance.insert(&link_head, &random); &random doesn't point to a Node, thus the compiler error
int insert(Node *, Node *); should be static int insert(Node **, Node *); and used as follows
Node* head = NULL;
for (int i = 0; i < 20; i++)
{
Node* newNode = new Node;
newNode->data = rand() % 100;
Node::insert(&head, newNode);
}
Where the implementation looks like:
int Node::insert(Node** link_head, Node *newNode)
{
if(!link_head) {
return -1;
}
if(!(*link_head)) {
*link_head = newNode;
}
else {
newNode->next = (*link_head)->next;
(*link_head)->next = new_node;
}
return 0;
}
The difference is you use a head reference as an anchor for the linked list and you'll not have a useless instance that always needs to be sorted out from the actual values stored in the list.