File Input Output Streams

I am trying to get this program to take information from a text file and input it into the list at the very beginning. At the end of it I am trying to make it output the information back to the same text file. Both parts seem to not be working. There are some other functions that I have taken out so that the program fits.
#include <iostream>
#include <iomanip>
#include <sstream>
#include <vector>
#include <cstdlib>
#include <climits>
#include <fstream>
using namespace std;

class Product {
public:
    Product();
    Product(string name, double price, int qty);
    string getName() const;
    double getPrice() const;
    int getQuantity() const;
    double getValue() const;
    void setName(string newName);
    void setPrice(double newPrice);
    void setQuantity(int newQuantity);
    void print() const;
    void read();
    string toString();
    void read(ifstream& fin);
    void write(ofstream& fout) const;
private:
    string name;
    double price;
    int quantity;
};

const int NAME_WIDTH = 20;
const int PRICE_WIDTH = 10;
const int QTY_WIDTH = 10;
const int VALUE_WIDTH = 14;

double readDouble(string prompt);

void saveData(const vector<Product>& store, string fileName);
Product::Product() {
    price = 0.0;
    quantity = 0;
}

Product::Product(string name, double price, int qty) {
    setName(name);
    setPrice(price);
    setQuantity(qty);
}


void Product::read() {
    cout << "Enter the name of the product: ";
    cin >> ws;
    getline(cin, name);
    // Making use of the extra credit function
    setPrice(readDouble("Enter the price for a " + name + ": "));
    setQuantity((int) readDouble("Enter the initial inventory: "));
}

void Product::read(ifstream& fin) {
    fin >> name;
    fin >> price;
    fin >> quantity;
}

void Product::write(ofstream& fout) const {
    fout.open("products.txt");
    if (fout.fail()) {
        cout << "Output file failed to open.\n";
        exit(-1);
    }
    cout << "Writing this to a file.\n";
    fout << name;
    fout << price;
    fout << quantity;
    fout.close();
}

void listProducts(vector<Product>& store);

void addProduct(vector<Product>& store);

void deleteProduct(vector<Product>& store);

void sellProduct(vector<Product>& store);

void restockProduct(vector<Product>& store);

int getProductIndex(vector<Product>& store);

int readIntInRange(string prompt, int min, int max);

void loadData(vector<Product>& store, string fileName);

void saveData(const vector<Product>& store, string fileName);

const int INVENTORY = 1;
const int ADD_PROD = 2;
const int DEL_PROD = 3;
const int SELL_PROD = 4;
const int RESTOCK = 5;
const int EXIT = 0;

const int MAX_ADD = 1000;


int main() {

    const double MILK_PRICE = 3.95;
    const int MILK_QTY = 40;
    const double BREAD_PRICE = 2.99;
    const int BREAD_QTY = 30;
    const double CHEESE_PRICE = 4.98;
    const int CHEESE_QTY = 20;
    Product milk("Milk", MILK_PRICE, MILK_QTY);
    Product bread("Bread", BREAD_PRICE, BREAD_QTY);
    Product cheese;
    cheese.setName("Cheese");
    cheese.setPrice(CHEESE_PRICE);
    cheese.setQuantity(CHEESE_QTY);

    ifstream fin;
    ofstream fout;
    fin.open("products.txt");
    vector<Product> store;
    store.push_back(milk);
    store.push_back(bread);
    store.push_back(cheese);
    loadData(store, "products.txt");

    cout << "Welcome to the Virtual Store Manager\n";
    int choice = 1;
    while (choice != 0) {
    string msg = "\nPlease choose one of the following operations:\n";
    msg += "0. Exit program\n";
    msg += "1. Report inventory\n";
    msg += "2. Add a new product\n";
    msg += "3. Delete a product\n";
    msg += "4. Sell a product\n";
    msg += "5. Restock a product\n";
    msg += "Choice (0-5): ";
    choice = readIntInRange(msg, 0, 5);
        if (choice == INVENTORY) {
            listProducts(store);
        } else if (choice == ADD_PROD) {
            addProduct(store);
        } else if (choice == DEL_PROD) {
            deleteProduct(store);
        } else if (choice == SELL_PROD) {
            sellProduct(store);
        } else if (choice == RESTOCK) {
            restockProduct(store);
        } else if (choice != EXIT) {
            cout << "\nInvalid choice!\n";
        }
    }
    cout << "\nGoodbye!\n";
    saveData(store, "products.txt");

    fin.close();
    fout.close();

    return 0;
}

int getProductIndex(vector<Product>& store) {
    listProducts(store);
    int pos = readIntInRange("Enter the number of the product: ",
        1, store.size());
    return pos - 1;
}

void sellProduct(vector<Product>& store) {
    cout << "\nSelling a product:";
    int pos = getProductIndex(store);
    Product prod = store[pos];
    int inventory = prod.getQuantity();
    if (inventory > 0) {
        prod.setQuantity(inventory - 1);
        store[pos] = prod;
    } else {
        cout << "Sorry, " << prod.getName() << " is sold out.\n";
    }
}

void restockProduct(vector<Product>& store) {
    cout << "\nRestocking a product:";
    int pos = getProductIndex(store);
    Product prod = store[pos];
    int inventory = prod.getQuantity();
    int numItems = readIntInRange("Number of items to add: ", 0, MAX_ADD);
    inventory += numItems;
    prod.setQuantity(inventory);
    store[pos] = prod;
}

void deleteProduct(vector<Product>& store) {
    cout << "\nDeleting a product:";
    int pos = getProductIndex(store);
    for (unsigned i = pos; i < store.size() - 1; i++) {
        store[i] = store[i + 1];
    }
    store.pop_back();
}

void loadData(vector<Product>& store, string filename) {
    ifstream fin(filename.c_str());
    if (fin.fail()) {
        cout << "Input file failed to open.\n";
        exit(-1);
    }
    string line;
    fin >> ws;
    while(getline(fin, line)) {
        Product temp;
        temp.read(fin);
        if (fin.good()) {
            store.push_back(temp);
        }
    }
    fin.close();
}

void saveData(const vector<Product>& store, string filename) {
    ofstream fout(filename.c_str());

    if (fout.fail()) {
        cout << "Output file failed to open.\n";
        exit(-1);
    }
    for (unsigned int i = 0; i < store.size(); i++) {
        store[i].write(fout);
    }
    fout.close();
}

void addProduct(vector<Product>& store) {
    cout << "\nAdding a new product:\n";
    Product prod;
    prod.read();
    store.push_back(prod);
}


void listProducts(vector<Product>& store) {
    const int HASH_WIDTH = 3;
    cout << endl;
    cout << setw(NAME_WIDTH + HASH_WIDTH) << left << " # Name"
         << setw(PRICE_WIDTH) << right << "Price"
         << setw(QTY_WIDTH) << right << "Qty"
         << setw(VALUE_WIDTH) << "Value" << endl;
    for (unsigned num = 0; num < store.size(); num++) {
        cout << setw(2) << right << (num + 1) << " ";
        store[num].print();
    }
}

double readDouble(string prompt) {
    double input = 0.0;
    bool more = true;
    while (more) {
        cout << prompt;
        cin >> input;
        if (cin.fail()) {
            cout << "Error: enter numbers only!\n";
            cin.clear();
            cin.ignore(INT_MAX, '\n');
        } else {
            more = false;
        }
    }

    return input;
}
int readIntInRange(string prompt, int min, int max) {
    int input = 0;
    bool more = true;
    while (more) {
        cout << prompt;
        cin >> input;
        if (cin.fail()) {
            cout << "Error: enter integer numbers only!\n";
            cin.clear();
            cin.ignore(INT_MAX, '\n');
        } else if (input < min || input > max) {
            cout << "Error: enter integer numbers between " << min
                 << " and " << max << ".\n";
        } else {
            more = false;
        }
    }
    return input;
}
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