How to loop ofstream in C++?

Question

Program idea: Console will prompt user to key in their fuel consumption details. After a full set of data is keyed in (date, amount, brand and mileage) and I continue on with the program, logging in as much as I want and finally decide to output the text into notepad, the text document will show me all the entries I've keyed in. The for loop works like it should, looping infinitely until user inputs 'N' or 'n'.

ISSUE: My issue with this is that no matter how many entries I key in and continue, my output text document will only show me the last entry I keyed in. Why is this so?

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

using namespace std;

int main()
{
    int count = 0;
    double amount, mileage;
    string date, brand;
    char ans;

    cout << "****************************" << endl;
    cout << "CAR FUEL CONSUMPTION HISTORY" << endl;
    cout << "****************************" << endl;

    for (;;)
    {
        cout << "\nDate (dd/mm/yy): ";
        cin >> date;

        cout << "Amount Payable: $";
        cin >> amount;

        cout << "Brand: ";
        cin >> brand;

        cout << "Mileage (km): ";
        cin >> mileage;

        cout << "\nContinue? (Y/N): ";
        cin >> ans;

        if (ans == 'N' || ans == 'n')
        {
            break;
        }
        else
        {
            count++;
        }
    }

    ofstream openFile;
    openFile.open("conHist.txt");

    // NOT WORKING!!!! >:(
    while(openFile.good())
    {
        openFile << "Entry " << count << endl;;
        openFile << "Date (dd/mm/yy): " << date << endl;
        openFile << "Amount Payable: $" << amount << endl;
        openFile << "Brand: " << brand << endl;
        openFile << "Mileage: " << mileage << "km" << endl;
        openFile.close();
    }

    return 0;
}

Answer 1

You are not storing your data, but overwriting it in the loop:

for (;;)
{
    cout << "\nDate (dd/mm/yy): ";
    cin >> date;

    cout << "Amount Payable: $";
    cin >> amount;

    cout << "Brand: ";
    cin >> brand;

    cout << "Mileage (km): ";
    cin >> mileage;

    cout << "\nContinue? (Y/N): ";
    cin >> ans;

    if (ans == 'N' || ans == 'n')
    {
        break;
    }
    else
    {
        count++;
    }
}

You need to place the data into some type of container like std::vector.

Also, I recommend creating a structure to hold all the data for one entry:

struct Fuel_Record
{
  std::string date;
  double      amount;
  std::string brand;
  double      mileage;
};

You can then create a container to hold all the data you've collected:

std::vector<Fuel_Record> fuel_database;

Your input loop can be modified as:

Fuel_Record f;
for (;;)
{
    cout << "\nDate (dd/mm/yy): ";
    cin >> f.date;

    cout << "Amount Payable: $";
    cin >> f.amount;

    cout << "Brand: ";
    cin >> f.brand;

    cout << "Mileage (km): ";
    cin >> f.mileage;

    // Add the record to the container
    fuel_database.push_back(f);

    cout << "\nContinue? (Y/N): ";
    cin >> ans;

    if (ans == 'N' || ans == 'n')
    {
        break;
    }
    else
    {
        count++;
    }
}

Edit 1: Not storing the data
You may not have learned about containers or structures. In that case, you will need to process the data after you have collected it:

double total_payable = 0.0;
double total_mileage = 0.0;
for (;;)
{
    cout << "\nDate (dd/mm/yy): ";
    cin >> date;

    cout << "Amount Payable: $";
    cin >> amount;

    cout << "Brand: ";
    cin >> brand;

    cout << "Mileage (km): ";
    cin >> mileage;

    cout << "\nContinue? (Y/N): ";
    cin >> ans;

    // Process the collected data:
    total_mileage += mileage;
    total_payable += payable;

    if (ans == 'N' || ans == 'n')
    {
        break;
    }
    else
    {
        count++;
    }
}