Irregular code execution

I have been making a program for a local... place, and it is a program that will calculate how much pizza will should be ordered. The problem, however, is not even the calculations, but rather with the files that keep log-in I.D. data.

#include <iostream>
#include <stdlib.h>
#include <iomanip>
#include <fstream>

using namespace std;
string logs[20];

void test(ifstream& IN, string logs[], ofstream& OUT);
void introduction();
int logging_in(string id, string logs[]);
void menu();


string newl = "\n";
string dnewl = "\n\n";
string tnewl = "\n\n\n";
string qnewl = "\n\n\n\n";
string pnewl = "\n\n\n\n\n";



int main()
{

    ifstream IN;
    ofstream OUT;


    string id;

    IN.open("loginn.dat");

    cout << IN.is_open();

    test(IN, logs, OUT);



string sup;
    int receive = 0;
    introduction();










    return 0;
}

void test(ifstream& IN, string logs[], ofstream& OUT)
{
   for (int x = 0; x < 20; x++)
    {
        IN >> logs[x];
    }

    IN.close();
    OUT.open("loginn.dat");

    for (int x = 0; x < 20; x++)
    {
        OUT << logs[x] << " " << "hue" << " ";

    }
}

void introduction()
{
    string cont;

     cout << "Hello.  I am the..." << dnewl
         << "Statistical" << newl << "Pizza" << newl
         << "Order" << newl << "Amount" << newl
         << "Diagnostic." << dnewl

         << "Otherwise known as Pizzahand.  I will be assisting you to estimate the \namount of pizza that is to be ordered for <INSERT NAME>, as to \neliminate excessive ordering."
         << tnewl;

         cout << "Press Enter to continue..." << newl;
         cin.get();
}

In theory this is supposed to output the array "logs[]" before executing the rest of the code. This was the case when I had no functions in addition to the main function. As soon as I started to use my next function, "introduction()", the code for reading the text file here

for (int x = 0; x < 20; x++)
        {
            IN >> logs[x];
        }

seemed to be knocked out of order. Instead of performing this task before anything else, it seems as if it does it at the very end of the program as I have tested by outputting its contents while the program was still reading "test()", with no luck. After the main function returns "0", however, I see that my program has outputted data into a test file, "loginns.dat", properly. It is imperative for my program that this login ID data gets read in at the beginning as when the program transitions to logging in, the data is needed. Also, I have tried placing these arrays and for loops in different locations: in the log-in functions themselves, in the main function, and even another function that I created out of desperation.

I have searched for hours on how to solve this to no avail and experimented myself for plenty of hours more. Every step I took to attempt to fix this lead to more dead ends, or more questions. I am quite the beginner in the sense that this school-year is the first year of studying c++, and I am desperate for an expert opinion (or anyone knowledgeable) to help me face the right direction.

Thank you.