C++ linker undefined reference to function cannot find my error - c++

Question

It is a homework problem. It compiles fine, but linker gives undefined reference to my function getSalesData - line 20 just after my first for loop. Here is the code. I cannot find where I have done anything incorrectly; I have my prototype defined and it matches my function header, and I am simply calling the function.
// chips and salsa
#include <iostream>
#include <iomanip>
#include <string>
int getJarsSold(std::string type);
void getSalesData(int jarsSold[],int size,int &totalJars,int &highSeller,int &lowSeller);
int main() {
const int SIZE = 5;
const std::string salsaTypes[] {"Mild","Medium","Sweet","Hot","Zesty"};
int jarsSold[SIZE] = {};
int highIndex,lowIndex,totalJarsSold;
for (int i = 0; i < SIZE; i++) {
jarsSold[i] = getJarsSold(salsaTypes[i]);
}
getSalesData(jarsSold,SIZE,totalJarsSold,highIndex,lowIndex);
std::cout << " Type Jars Sold\n";
std::cout << "---------------------\n";
for (int i = 0; i < SIZE; i++) {
std::cout << std::setw(8) << salsaTypes[i] << std::setw(15) << jarsSold[i] << std::endl;
}
std::cout << "*********************\n";
std::cout << "Total Sales = " << totalJarsSold << std::endl;
std::cout << "Highest Seller = " << salsaTypes[highIndex] << std::endl;
std::cout << "Lowest Seller = " << salsaTypes[lowIndex] << std::endl;
}
int getJarsSold(std::string type) {
bool validData = false;
int numJars;
while (!validData) {
std::cout << "Enter jars sold this month for " << type << " salsa type: ";
std::cin >> numJars;
if (numJars < 0) {
std::cout << "Number of jars sold must be 0 or positive number.\n";
}
else {
validData = true;
}
}
validData = false;
return numJars;
}
void getSalesData(int jarsSold[],int size,int totalJars,int highIndex,int lowIndex) {
bool firstRun = true;
int highVal,lowVal;
totalJars = 0;
for (int i = 0; i < size; i++) {
if (firstRun) {
highIndex = i;
highVal = jarsSold[highIndex];
lowIndex = i;
lowVal = jarsSold[lowIndex];
totalJars += jarsSold[i];
firstRun = false;
}
else {
totalJars += jarsSold[i];
if (jarsSold[i] > highVal) {
highVal = jarsSold[i];
highIndex = i;
}
if (jarsSold[i] < lowVal) {
lowVal = jarsSold[i];
lowIndex = i;
}
}
}
}
Any help is appreciated. I am just using -c for compiling and -o for linking, nothing fancy as I know no better.