C++ Vectors

This is my first time working with Vectors and I'm getting LNK errors
Here's my isolated code.

#include <iomanip>
#include <string>
#include <iostream>
#include <cstdlib>
#include <vector>
#include <fstream>
using namespace std;

void input(ifstream& in, ofstream& out, vector<double> item_ID);


int main()
{
    vector<double> item_ID;
    vector<string> item_name;
    vector<double> ordered;
    vector<double> stock;
    vector<double> sold;
    vector<double> m_price;
    vector<double> o_price;
    ifstream in;
    ofstream out;

    in.open("c:\\a9data.txt");

    input(in, out, item_ID);
    system("pause");
}

void input(ifstream& in, ofstream& out, vector<double>& item_ID)
{
    in.open("c:\\a9data.txt");
}

>>10
Don't forget to deindent your code next time!