// This program allows the user to edit a specific record.
#include <iostream>
#include <fstream>
using namespace std;

const int DESC_SIZE = 31;  // Description size

// Declaration of InventoryItem structure
struct InventoryItem
{
   char desc[DESC_SIZE];
   int qty;
   double price;
};

int main()
{
   InventoryItem record;  // To hold an inventory record
   long recNum;           // To hold a record number

   // Open the file in binary mode for input and output
   fstream inventory("Inventory.dat",
                     ios::in | ios::out | ios::binary);

   // Get the record number of the desired record.
   cout << "Which record do you want to edit? ";
   cin >> recNum;

   // Move to the record and read it.
   inventory.seekg(recNum * sizeof(record), ios::beg);
   inventory.read(reinterpret_cast<char *>(&record),
                 sizeof(record));

   // Display the record contents.
   cout << "Description: ";
   cout << record.desc << endl;
   cout << "Quantity: ";
   cout << record.qty << endl;
   cout << "Price: ";
   cout << record.price << endl;

   // Get the new record data.
   cout << "Enter the new data:\n";
   cout << "Description: ";
   cin.ignore();
   cin.getline(record.desc, DESC_SIZE);
   cout << "Quantity: ";
   cin >> record.qty;
   cout << "Price: ";
   cin >> record.price;

   // Move back to the beginning of this record's position.
   inventory.seekp(recNum * sizeof(record), ios::beg);

   // Write the new record over the current record.
   inventory.write(reinterpret_cast<char *>(&record),
                  sizeof(record));

   // Close the file.
   inventory.close();
   return 0;
}