Binary File - Editing - c++

Question

Please help i am having trouble with this function. The code compiles and everything however it doesnt change anything in the file. I am so confused what i am supposed to do.... I am supposed to choose a record from the file to edit and then change it, my current code allows me to choose but when i edit the record nothing is stored?
void editRecord(Cookie &type)
{
fstream dataFile;
int num;
int count = 0;
dataFile.open("/Users/jordanmcpeek/Documents/2014_Summer/CSC_250/Unit_7/cookie.dat", ios::in | ios::out | ios::binary);
dataFile.read(reinterpret_cast<char *>(&type), sizeof(type));
// While not at the end of the file, display the records
while (!dataFile.eof())
{
// Display the records.
cout << endl;
cout << count << ". Description: ";
cout << type.description << endl;
cout << "Quantity Sold: ";
cout << type.quantity << endl;
cout << "Price: $";
cout << type.price << endl;
dataFile.read(reinterpret_cast<char *>(&type), sizeof(type));
count++;
}
cout << "Which record would you like to edit?: ";
cin >> num;
cout << endl;
cin.ignore();
dataFile.seekp(num * sizeof(type), ios::beg);
cout << "Please enter the new description for the cookie: ";
cin.getline(type.description, SIZE);
cout << endl;
do
{
cout << endl;
cout << "Please enter the new amount sold: ";
cin >> type.quantity;
cin.ignore();
}while(type.quantity < 0);
cout << endl;
do
{
cout << "Please enter the new price: $";
cin >> type.price;
cin.ignore();
}while(type.price < 0);
cout << endl;
// Change the record
dataFile.write(reinterpret_cast<char *>(&type), sizeof(type));
dataFile.close();
}