C++ - How to call variables from functions without using global variables - c++

Question

I've been trying to complete a task but I am not allowed to use global variables.
The task if that you have to make a coffee shop program where user can buy coffee (small, medium or large), then show the total number of coffee cups sold and then then total sales made from selling coffee. I completed half of the code where user can buy but I am stuck at summing coffee sales/cups.
The function cupsSold and totalAmount return 0 or garbage value. Also I am not allowed to use extra library functions.
Is there any way to call variables from another function without using global variables?
This is my main code:
#include <iostream>
using namespace std;
void showChoices()
{
cout << "Welcome to Jason's Coffee Shop\n\n";
cout << "1. Buy Coffee" << endl;
cout << "2. Show total cups sold by size"<< endl;
cout << "3. Show total amount of coffee sold"<<endl;
cout << "4. Show total amount of money made"<< endl;
cout << "0. Exit" << endl;
cout << "\nYour choice: ";
}
void buyCoffee(int numberSmCups,float totalSmCups,int numberMedCups,float totalMedCups, int numberLgCups,float totalLgCups)
{
char coffeeSize, order = 'y';
bool coffeeSelect = true;
float smCoffee = 1.75, mdCoffee = 1.90, lgCoffee = 2.00, totalCoffee = 0;
while(coffeeSelect)
{
if (order == 'y' ||order =='Y'){
cout << "Size of Coffee [S, M, L]: ";
cin >> coffeeSize;
if (coffeeSize == 's' || coffeeSize == 'S')
{
cout << "Quantity of Small Coffee: ";
cin >> numberSmCups;
totalSmCups = numberSmCups * smCoffee;
cout << "Small Coffee: "<<numberSmCups<<", Bill: "<<totalSmCups<<endl;
totalCoffee += totalSmCups;
cout << "Add another coffee [Y or N]: "<<endl;
cin >> order;
}
else if (coffeeSize == 'm' || coffeeSize == 'M')
{
cout << "Quantity of Medium Coffee: ";
cin >> numberMedCups;
totalMedCups = numberMedCups * mdCoffee;
cout << "Medium Coffee: "<<numberMedCups<<", Bill: "<<totalMedCups<<endl;
totalCoffee += totalMedCups;
cout << "Add another coffee [Y or N]: "<<endl;
cin >> order;
}
else if (coffeeSize == 'l' || coffeeSize == 'L')
{
cout << "Quantity of Large Coffee: ";
cin >> numberLgCups;
totalLgCups = numberLgCups * lgCoffee;
cout << "Large Coffee: "<<numberLgCups<<", Bill: "<<totalLgCups<<endl;
totalCoffee += totalLgCups;
cout << "Add another coffee [Y or N]: ";
cin >> order;
}
}
else
break;
}
cout << "--------------\n";
cout << "Your invoice: "<<endl;
cout<< endl;
if (numberSmCups>= 1)
cout << "Small Coffee: "<< numberSmCups <<" cups ($ "<< smCoffee <<"/cup) Amount: $ "<< totalSmCups << endl;
if (numberMedCups>=1)
cout << "Medium Coffee: "<< numberMedCups <<" cups ($ "<< mdCoffee << "/cup) Amount: $ "<< totalMedCups << endl;
if (numberLgCups>=1)
cout << "Large Coffee: " << numberLgCups <<" cups ($ " << lgCoffee << "/cup) Amount: $ " << totalLgCups << endl;
cout<< endl;
cout << "Total Amount: "<<"$ "<< (totalSmCups+ totalMedCups+ totalLgCups) << endl;
cout << "--------------" << endl;
}
void cupsSold(int numberSmCups,int numberMedCups,int numberLgCups){
int lifeSmCups=0;
int lifeMdCups=0;
int lifeLgCups=0;
lifeSmCups = lifeSmCups + numberSmCups;
lifeMdCups = lifeMdCups + numberMedCups;
lifeLgCups = lifeLgCups + numberLgCups;
cout << "Total Small cups: "<<lifeSmCups<<endl;
cout << "Total Medium Cups:"<<lifeMdCups<<endl;
cout << "Total Large Cups:"<<lifeLgCups<<endl;
}
void totalAmount(float totalCoffee)
{
cout << "Total: "<<"$"<<totalCoffee<<endl;
}
int main()
{
int numberSmCups = 0, numberMedCups = 0, numberLgCups = 0, choice;
float totalSmCups = 0, totalMedCups = 0, totalLgCups = 0, totalCoffee;
while (choice != 0)
{
showChoices();
cin >> choice;
cout << endl;
if (choice == 1)
{
cout <<"You selected to buy coffee."<< endl;
buyCoffee(numberSmCups,totalSmCups,numberMedCups,totalMedCups,numberLgCups,totalLgCups);
}
else if (choice == 2)
{
cout << "The total amount of cups sold by size is: "<<endl;
cupsSold(numberSmCups,numberMedCups,numberLgCups);
}
else if (choice == 3)
{
cout << "Total Coffee Sold: "<<endl;
// cupsSold(numberSmCups,numberMedCups,numberLgCups);
}
else if (choice == 4)
{
cout << "Money made from coffee sales: "<<endl;
totalAmount(totalCoffee);
}
else if (choice == 0)
{
cout << "EXIT"<<endl;
break;
}
else
cout << "Invalid Input" << endl;
}
return 0;
}

Answer 1

"Is there any way to call variables from another function without using global variables?"
You need to use by reference parameters, if you want to change the variables passed to a function like this
void cupsSold(int& numberSmCups,int& numberMedCups,int& numberLgCups){
// ^ ^ ^
otherwise these functions just operate on copies rather than your original variable values.