Item Inventory Add/Edit/View questions

Okay so i have a lot of questions for this. I was having a lot of trouble but am getting there slowly. So far I have it to where the program will read and write to a file, but it tends to repeat itself a lot. Like when reading from the file itll just keep reading the same information over and over. And when writing it just keep asking for information over and over without ever stopping. Also it seems to display the same record twice...and i cant test it further since it only lets me write the first record over and over without ever writing the second. Any help would be great.

#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>

using namespace std;

void addRecord(fstream &);
void viewRecord(fstream &);
void changeRecord(fstream &);
int menu();

const int DESC_SIZE = 21;
const int DATE_SIZE = 11;

struct inventoryData

{
        char desc[DESC_SIZE]; //Desc up to 20 chars
        int quantity; //Item quantity
        double wholesale; //Item wholsale Cost
        double retail; //Item retail Cost
        char date[DATE_SIZE]; //Date able to hold info up to xx/xx/xxxx

};


int main()
{
    int selection;
    int recordNumber;

    fstream dataFile("inventory.dat", ios::in | ios::out | ios::binary);
    if (dataFile.fail())
    {
        // The file does not exist, so create it.
        dataFile.open("inventory.dat", ios::out);
    }


    selection = menu();

    while (selection != 4)
    {
        switch (selection)
            {
                case 1:
                    {
                         viewRecord(dataFile);
                         break;
                    }
                case 2:
                {
                          addRecord(dataFile);
                          break;
                }
                case 3:
                    {
                         changeRecord(dataFile);
                         break;
                    }
                default:
                    {
                        cout << "Invalid - Please use 1 to 4" << endl;
                        break;
                    }
                    selection = menu();
            }
    }

    dataFile.close();

    return 0;
}

void addRecord(fstream &file)
{
    fstream dataFile("inventory.dat", ios::in | ios::out | ios::binary);
    inventoryData item;

    cout << "Please enter the following data about the item" << endl;
    cout << "Description: ";
    cin.ignore();
    cin.getline(item.desc, DESC_SIZE);
    cout << "Quantity: ";
    cin >> item.quantity;
    cout << "Quantity: ";
    cin >> item.quantity;
    cout << "Wholesale cost: ";
    cin >> item.wholesale;
    cout << "Retail price: ";
    cin >> item.retail;
    cout << "Date (Please use MO/DA/YEAR format: ";
    cin >> item.date;
    dataFile.write(reinterpret_cast<char *>(&item), sizeof(item));

    return;
}

void viewRecord(fstream &file)
{
    string output;
    fstream dataFile("inventory.dat", ios::in | ios::out | ios::binary);

    inventoryData item;
    fstream items;
    char again;

    dataFile.read(reinterpret_cast<char *>(&item), sizeof(item));

    while (!items.eof())
    {
    // Display the record.
    cout << "Description: " << item.desc << endl;
    cout << "Quantity: " << item.quantity << endl;
    cout << "Wholesale Cost: " << item.wholesale << endl;
    cout << "Retail Cost: " << item.retail << endl;
    cout << "Date: " << item.date << endl;

    // Wait for the user to press the Enter key.
    cout << "\nPress the Enter key to see the next record.\n";

    cin.get(again);
    // Read the next record from the file.
    dataFile.read(reinterpret_cast<char *>(&item), sizeof(item));
    }
}


void changeRecord(fstream &file)
{
    fstream dataFile("inventory.dat", ios::in | ios::out | ios::binary);

    inventoryData item;
    int recordNumber;

    cout << "Please choose a record number you want to edit" << endl;
    cin >> recordNumber;
    dataFile.seekg(recordNumber * sizeof(item), ios::beg);
    dataFile.read(reinterpret_cast<char *>(&item), sizeof(item));
    cout << "Description: " << item.desc << endl;
    cout << "Quantity: " << item.quantity << endl;
    cout << "Wholesale cost: " << item.wholesale << endl;
    cout << "Retail price: " << item.retail << endl;
    cout << "Date: " << item.date << endl;
    cout << endl;

    // Get the new record data.
    cout << "Enter the new data:\n";
    cout << "Description: ";
    cin.ignore();
    cin.getline(item.desc, DESC_SIZE);
    cout << "Quantity: ";
    cin >> item.quantity;
    cout << "Quantity: ";
    cin >> item.quantity;
    cout << "Wholesale cost: ";
    cin >> item.wholesale;
    cout << "Retail price: ";
    cin >> item.retail;
    cout << "Date (Please use MO/DA/YEAR format: ";
    cin >> item.date;

    // Move back to the beginning of this record's position
    dataFile.seekp(recordNumber * sizeof(item), ios::beg);
    // Write new record over the current record
    dataFile.write(reinterpret_cast<char *>(&item), sizeof(item));

}

int menu()
{
    int menuSelection;

    cout << fixed << showpoint << setprecision(2);
    cout << "----------Inventory----------" << endl;
    cout << "1 - View inventory" << endl;
    cout << "2 - Add an item" << endl;
    cout << "3 - Edit an item" << endl;
    cout << "4 - End Program" << endl;
    cin >> menuSelection;

    if (!cin)
    {
        cout << "Invalid - Please use 1 to 4" << endl;
        cin >> menuSelection;
    }

    if (menuSelection < 1 || menuSelection > 4)
    {
        cout << "Invalid - Please use 1 to 4" << endl;
        cin >> menuSelection;
    }

    return menuSelection;
}