Problems finding out total sum using data structures and arrays - c++

Question

I have this code that has several funtions and am almost done, I just am having trouble finding the rental cost on my program.
My program reads a text file of cars and the rental cost as shown here:
2014 Toyota Tacoma 115.12 1
2012 Honda CRV 85.10 0
2015 Ford Fusion 90.89 0
2013 GMC Yukon 110.43 0
2009 Dodge Neon 45.25 1
2011 Toyota Rav4 65.02 1
2012 Mazda CX5 86.75 1
2016 Subaru Outback 71.27 0
2015 Ford F150 200.83 1
2010 Toyota Corolla 50.36 1
The float character is the price ( rental cost )
However I want the user to input the car number ( 1-10) choose how many days and output the rental cost. I am just having trouble how it would read the input of the car the user wants. This is my main code, but what I need is to tell if case 3 needs work.
#include <iostream>
#include <fstream>
using namespace std;
struct car {
int year;
char make[10];
char model[10];
float price;
int available;
} ;
void menu();
// Main Function
int main ()
{
// declare variables
int carAmount = 10;
int choice;
car carLib[carAmount];
char filename[10];
ifstream carInData;
float mostExpensive = 0;
int MostExpensiveIndex;
int count = 0;
int days;
int rentalCost = 0;
bool menu1 = false;
//prompt user for input file
cout << " Enter file name: ";
cin >> filename;
// Start loop menu
while(menu1 = true){
menu();
carInData.open(filename);
cin >> choice;
if (carInData.is_open()) {
// read list of names into array
for (; count < carAmount; count++) {
carInData >> carLib[count].year >> carLib[count].make >> carLib[count].model >> carLib[count].price >> carLib[count].available;
}
}
switch (choice) {
// Case 1 closes menu
case 1:
return 0;
break;
// Case 2 displays if car is available if 1, unavailable if 0
case 2:
// itterate through car array
for(count = 0; count < carAmount; count++){
// Displays if car is available or not
if (carLib[count].available == 1)
cout << " Available ";
else
cout << " Unavailable ";
// Display Cars
cout << carLib[count].year << " " << carLib[count].make << " " << carLib[count].model << " " << carLib[count].price << " " << "\n";
}
break;
// Display only available cars
case 3:
// itterate through car array
for(count = 0; count < carAmount; count++){
// Displays only available cars
if (carLib[count].available == 1){
cout << " Available ";
// Display Cars
cout << carLib[count].year << " " << carLib[count].make << " " << carLib[count].model << " " << carLib[count].price << " " << "\n";
}
}
break;
// Calculates rental cost
case 4:
cout << " Enter car number and how many days " << "\n";
cout << " Days: ";
cin >> days;
cout << "\n" << "Car: ";
cin >> carLib[count].price;
rentalCost += days*count;
cout << " Rental Cost for " << days << " days is " << rentalCost << "\n";
break;
// Finds most expensive car
case 5:
MostExpensiveIndex = count;
for (size_t carIndex = 0; carIndex < carAmount; ++carIndex) {
if (carLib[carIndex].price <= mostExpensive) continue;
mostExpensive = carLib[carIndex].price;
MostExpensiveIndex = carIndex;
}
const car & carI = carLib[MostExpensiveIndex];
cout << " Most Expensive car is: " << " " << carI.year << " " << carI.make << " " << carI.model << " " << carI.price << "\n";
break;
}
}
return 0;
}
void menu()
{
cout << " 1 - Exit program.\n";
cout << " 2 - Show Cars\n";
cout << " 3 - Show only available cars.\n";
cout << " 4 - Rental Cost\n";
cout << " 5 - Most Expensive Car\n";
}

Answer 1

Unless I'm misunderstanding something with how your code is suppose to work, I think case 3 works fine. HOWEVER, it's case 4 that you should be worried about
case 4:
cout << " Enter car number and how many days " << "\n";
cout << " Days: ";
cin >> days;
cout << "\n" << "Car: ";
cin >> carLib[count].price; // WHY IS THE USER CHANGING THE PRICE?
rentalCost += days*count; // WHY IS THE PRICE "DAYS * (CAR ID #)"
cout << " Rental Cost for " << days << " days is " << rentalCost << "\n";
break;
You can see my comments there. I would change this to
case 4:
cout << " Enter car number and how many days " << "\n";
cout << " Days: ";
cin >> days;
cout << "\n" << "Car: ";
cin >> count ;
// Note the decrement of 'count' by one, since you expect the user
// to enter a number 1-10
// Should probably include a check that the 'count' is valid
rentalCost += days*carLib[count-1].price;
cout << " Rental Cost for " << days << " days is " << rentalCost << "\n";
break;
Note that carLib increments from 0->9, but your user might think it counts from 1-10. It might help when you print option 2 (all car information) that you include the car ID number that you're expecting from the user.
Also a few more questions for you
You're storing the rental cost as an int (not sure if that's by design), so just remember that the days*price computation will get rounded.
The rentalCost is incrementing to be bigger and bigger, so I'm guessing the user is renting multiple cars?
You should maybe do a check as to whether the user can actually rent a car before increasing their rental cost.