Question

I’m having problems appending to a random-access file. I don’t seem to be able to overwrite a field within the file. Instead, I’m only appending to the file, and leaving the old name intact.

fstream Airline("AirLine.text", ios::out | ios::in | ios::app | ios::binary); 
if(!Airline)
{
    cout << "File Could not be opened." << endl;  
    system("PAUSE");
    exit (1);
}

cout << "Enter Seat Number to Update" << "(1 to 100, 0 to end)?";

NewPassenger passenger;
cin >> passenger.seat_number;

while (0 < passenger.seat_number && passenger.seat_number <= 100)
{
    Airline.seekp((passenger.seat_number - 1 ) * sizeof(NewPassenger));
    Airline.read(reinterpret_cast<char *>(&passenger), sizeof(NewPassenger));

    cout << " Found Record. Now Enter New Name:";
    cin >> passenger.name;

    Airline.seekg((passenger.seat_number - 1 ) * sizeof(NewPassenger),ios::beg);
    Airline.write(reinterpret_cast<const char *>(&passenger), sizeof(NewPassenger));

    cout << "\nEnter Seat Number: ?";
    cin >> passenger.seat_number;
}

Airline.close();
cout << endl;

NewPassenger is defined as follows:

struct NewPassenger
{ 
    int seat_number;
    char name[20];
    char onward[3];
};

Answer 1

fstream Airline("AirLine.text", ios::out | ios::in | ios::app | ios::binary);

Looking at cplusplus.com on fstream::open I see the append flag described as

app (append) Set the stream’s position indicator to the end of the stream before each output operation.

(Emphasis added). It looks like you are getting the behavior you asked for. Perhaps you wanted

ate (at end) Set the stream’s position indicator to the end of the stream on opening.