print link list

what is the error here ???

// linkme.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
using namespace std;
double val;
struct node {
typedef double item;
item data; // data stored in node
node *link; //pointer to next node
};

int _tmain(int argc, _TCHAR* argv[])
{

node *head_ptr;
node *tail_ptr;
node *insert_ptr;
node *print_ptr;
head_ptr=NULL;
tail_ptr=NULL;
insert_ptr=NULL;

cout << "Give Initial Value" <<endl ;
cin >> val;
insert_ptr = new node;
insert_ptr ->data=val; //vali to stixio tis listas sto proto kouti pou ekama
head_ptr = insert_ptr; // kamni point sto insert_ptr
tail_ptr = insert_ptr; //kamni to idio
insert_ptr =NULL; //Kamnoto null gia na figi

while ( val<100)
{
cout << "Give Value" <<endl ;
cin >> val;
insert_ptr = new node;
insert_ptr ->data=val;
insert_ptr = head_ptr;
head_ptr = insert_ptr;
insert_ptr = NULL;
};
print_ptr=head_ptr->link;

while ( print_ptr !=NULL)
{
cout << print_ptr->data;
print_ptr=print_ptr->link;
}
return(0);

}