Why is my vector dropping its data? - c++

Question

I'm writing a basic debt calculator to practice my C++ but one of my vectors keep dropping its values.
The structure containing the vector:
struct debt
{
std::string institution, debtType;
double creditLimit, balance, intrest, debtRatio, minMonthly;
int monthsToPayOff;
std::vector <double> monthlyBalance; //this vector is giving me trouble
};
I call a function that stores each months balance minus the monthly payment in the vector.
for (auto i : vectDebt)
{
double tempBalance = i.balance;
while (tempBalance > 0)
{
i.monthlyBalance.push_back(tempBalance); //this seems to work fine
tempBalance -= i.minMonthly;
}
if (i.monthlyBalance.size() > vectMonths.size())
vectMonths.resize(i.monthlyBalance.size());
}
Visual Studio debugger shows that the values were stored properly in above code. I then try to print the values to a .csv file but at that point the vector is already empty.
//print the payoff balances in debt.csv
for (auto i: vectDebt)
{
for (int j = 0; j != i.monthlyBalance.size(); j++)
{
fileout << i.monthlyBalance[j] << ","; //the debugger shows monthlyBalance has size = 0
}
fileout << "\n";
}
Here's my complete code, any additional comments on improving the program are also appriciated:
Debt.h
#pragma warning(disable : 4996) //diable localtime warning
#ifndef DEBT_H
#define DEBT_H
#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <time.h>
#include <vector>
struct debt
{
std::string institution, debtType;
double creditLimit, balance, intrest, debtRatio, minMonthly;
int monthsToPayOff;
std::vector <double> monthlyBalance;
};
class Debt
{
private:
time_t t = time(NULL);
tm *timeinfo = localtime(&t);
const std::string months[12] = { "January","February","March","April","May","June","July",
"August","September","October","November","December" };
std::ofstream fileout;
std::vector <debt> vectDebt;
std::vector <std::string> vectMonths;
public:
Debt() { }
void addDebt(debt temp)
{
vectDebt.push_back(temp);
}
std::string returnMonth(int month)
{
std::string currentMonth = months[month - 1];
return currentMonth;
}
void calcPayoff();
void printDebt();
void printPayoff();
~Debt() { }
};
#endif //DEBT_H
Debt.cpp
#include "Debt.h"
void Debt::calcPayoff()
{
for (auto i : vectDebt)
{
double tempBalance = i.balance;
while (tempBalance > 0)
{
i.monthlyBalance.push_back(tempBalance);
tempBalance -= i.minMonthly;
}
if (i.monthlyBalance.size() > vectMonths.size())
vectMonths.resize(i.monthlyBalance.size());
}
}
void Debt::printDebt()
{
fileout.open("debt.csv");
fileout << "Institution(type),Current Balance,Intrest,Min Monthly Payment,Credit Limit\n";
for (auto i : vectDebt)
{
fileout << std::fixed << std::setprecision(2) << i.institution << "("
<< i.debtType << "),"
<< i.balance << ","
<< i.intrest << ","
<< i.minMonthly << ","
<< i.creditLimit << "\n";
}
printPayoff();
fileout.close();
}
void Debt::printPayoff()
{
int monthCounter = timeinfo->tm_mon;
fileout << "\nBalance per Month until paid off:\n";
for (int i = 0; i != vectMonths.size(); i++)
{
vectMonths.at(i) = months[monthCounter % 12];
monthCounter++;
}
for (auto i : vectMonths)
fileout << i << ",";
fileout << "\n";
//print the payoff balances in debt.csv
for (auto i: vectDebt)
{
for (int j = 0; j != i.monthlyBalance.size(); j++)
{
fileout << i.monthlyBalance[j] << ",";
}
fileout << "\n";
}
}
source file:
#include "Debt.h"
void main() {
Debt newList;
int check = 1;
std::string institution = "",
debtType = "";
double balance = 0,
intrest = 0,
creditLimit = 0,
minMonthly = 0;
std::cout << "This program will ask you to enter each of your debts institution(bank name), "
<< "debt type(loan, credit, car), current balance, interest rate, credit limit, and minimum monthly payment.\n";
while (check == 1) {
debt temp;
if (check == 1) {
std::cout << "Enter name of institution: ";
std::cin >> temp.institution;
std::cout << "Enter debt type (loan, credit, car...): ";
std::cin >> temp.debtType;
std::cout << "Enter current balance: ";
std::cin >> temp.balance;
std::cout << "Enter inrest rate for this debt: ";
std::cin >> temp.intrest;
std::cout << "Enter credit limit for this debt: ";
std::cin >> temp.creditLimit;
std::cout << "Enter the minimum monthly payment for this debt: ";
std::cin >> temp.minMonthly;
temp.debtRatio = 100*(temp.balance/temp.creditLimit);
newList.addDebt(temp);
std::cout << "Add another debt? \n"
<< "1) Yes\n"
<< "2) No\n";
std::cin >> check;
}
}
newList.calcPayoff();
newList.printDebt();
}

Answer 1

for (auto i : vectDebt) {
//...
}
In this loop, i will be a copy of each item in vectDebt. Any changes to i will not be reflected in the items in vectDebt. What you want is a reference to each item in vectDebt. To do that change your loop to
for (auto& i : vectDebt) {
//...
}