TPS 12: Reading from a file

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//==============================================================================
// File:    tps12.cpp
// Author:  Hank Feild
// Date:    14-Apr-2021
// Purpose: Demonstrates reading in data from a file.
//==============================================================================
#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

struct Car {
    string make, model;
    int year, miles;
    bool has4WheelDrive;
};

/**
 * Reads in a car's information from the given input file stream. Data in the
 * file is expected to be in this format (one piece of data per line)
 * 
 *    make
 *    model
 *    year
 *    miles
 *    2WD (yes/no)
 * 
 * @param fin The input file stream to read the data from. 
 * @return A Car populated with the next chunk of data from the input stream.
 */
Car ReadCarFromFile(ifstream &fin){
    Car car;
    string fourWheelDriveResponse;

    // TODO 1: below is the code we used to read in info about a car from
    // the user. Adapt this to read in from the input file (fin). Do we 
    // need the prompts?

    cout << "Please enter the following data about the car:" << endl;

    cout << "Make (Ford/Toyota/etc.): ";
    getline(cin, car.make);

    cout << "Model (F-150, Corolla, etc.): ";
    getline(cin, car.model);

    cout << "Year: ";
    cin >> car.year;

    cout << "Miles: ";
    cin >> car.miles;
    cin.ignore();
    
    cout << "Does it have 4WD? [yes/no]: ";
    getline(cin, fourWheelDriveResponse);
    car.has4WheelDrive = fourWheelDriveResponse == "yes";

    return car;
}

/**
 * Prints out a Car in a nice format:
 * 
 *   <year> <make> <model> with <miles> miles with<out?> 4-wheel drive
 * 
 * @param car The Car to display.
 */
void PrintCar(Car car){
    cout << car.year << " " << car.make << " " << car.model
         << " with " << car.miles << " miles with";
    if(!car.has4WheelDrive){
        cout << "out";
    }
    cout << " 4-wheel drive" << endl;
}

/**
 * Asks the user for three cars, then prints them out.
 * 
 * @return The exit status of the program; 0 is good.
 */
int main(){
    vector<Car> cars;
    ifstream fin;
    string filename;
    Car car;

    cout << "Enter the name of the file with car data: ";
    getline(cin, filename);

    // TODO 2: Open the file for reading (the variable `filename` has the name
    // of the file and `fin` is our input file stream variable).

    
    // Check if it opened okay; we can exit if it didn't.
    if(!fin.is_open()){
        cout << "The file could not be opened.";
        exit(1);
    }

    // Read all the cars in from the file.
    while(fin.good()){
        // TODO 3: the invocation of ReadCarFromFile is missing an argument; fix it.
        car = ReadCarFromFile();

        // Only add the car if all of its data was read in without error
        // (fin.good() will be true if there were no errors).
        if(fin.good()){
            cars.push_back(car);
        }
    }

    // Close the file -- always do this once you're finished with a file.
    fin.close();

    // Add 10 miles to each car.    
    for(int i = 0; i < cars.size(); i++){
        cars.at(i).miles += 10;
    }

    // Print the cars.
    for(int i = 0; i < cars.size(); i++){
        PrintCar(cars.at(i));
    }

    return 0;
}