assistance with functions and function calling

[zT4NhbRD]

In this program the user is supposed to choose a menu item, then the program is supposed to run a specific function based on their choice. Problem is I can't get the program to run the function after the choice is made. It just keeps looping. Can anyone help me out?

Note: I am not to use pass by reference.

#include <iostream>
#include <iomanip>

using namespace std;

//Global Variables
enum transType { SCAN_ITEM = 1, DISCOUNT, RECEIPT, EXIT};
const double TAX = 0.0825;

int main ()
{
    cout.precision (2);
    double itemPrice = 0.0, totalCost=0.0;
    //initialize function variables
    int choice, menuSelection;
    double price, runningTotal, givenDiscount; 
    //initialize functions
    double getDiscountRate(double discountRate);
    double getPrice(double itemPrice, double totalCost);
    void printReceipt(double totalCost, double discountRate);
    int showMenu(int choice);
   
    do {
         showMenu(menuSelection);
         switch (menuSelection)
         {
             case SCAN_ITEM:
                  getPrice (price, runningTotal);                 
                  break;
             case DISCOUNT:
                  getDiscountRate(givenDiscount);
                  break;
             case RECEIPT:
                  printReceipt(runningTotal, givenDiscount);         
                  break;
             case EXIT:
                  printReceipt(runningTotal, givenDiscount);
                  cout << "System Exit\n" << endl;
                  break;
         }
    } while (menuSelection != EXIT);
    system ("pause");
    return 0;
}
//Functions
int showMenu(int choice)
{
    cout << "Supermarket POS System\n"
         << "----------------------------------\n"
         << "Select an option:\n"
         << SCAN_ITEM << ". Scan an Item\n"
         << DISCOUNT << ". Set Discount Rate\n"
         << RECEIPT << ". Print Receipt\n"
         << EXIT << ". Exit\n"
         << "\n >>";
    cin  >> choice;
    return (choice);
}
double getPrice(double itemPrice, double totalCost)
{
    do {
         cout << "Enter the item price (positive number only): ";
         cin >> itemPrice;
         if (itemPrice <= 0) {
             cout << "Please enter a positive number only.\n" << endl;
         }
         else {
         totalCost += itemPrice;
         cout << "Running Total: " << fixed << totalCost << "\n" << endl;
         }
    } while (itemPrice <= 0);
    return (totalCost);
}
double getDiscountRate(double discountRate)
{
    cout << "Enter the Discount Rate (0.0-1.0): ";
    cin >> discountRate;
    cout << "Customer discount is at " << discountRate*100 <<"% off.\n" << endl;
    return (discountRate);
}
void printReceipt(double totalCost, double discountRate)
{
    double discountTotal, taxTotal;
    discountTotal = totalCost*discountRate;
    taxTotal = (totalCost-discountTotal)*TAX;
    cout << "Total Purchase:\t " << setw(8) << totalCost << "\n";
    if (discountRate > 0) {
    cout << "Discount:\t" << "-" << setw(8) << discountTotal << "\n";
    }
    cout << "Tax:\t\t" << "+" << setw(8) << taxTotal << "\n";
    cout << "Total Charge:\t" << "=" << setw(8) <<totalCost - discountTotal + taxTotal << "\n" << endl;
}

[Computergeek01]

You're not saving the data returned from "showMenu()", or from any other functions for that matter, anywhere. Nor are you passing 'menuSelection' by reference.

[zT4NhbRD]

I thought I was with the return in showMenu() with return(choice)?

Sorry I'm really new to all of this, could you maybe explain a little further how I could fix this? Thanks :)

[TarikNeaj]

To add to @Computergeek01 and to answer your question @Skyllianfive

Yes, you do return them from each function, BUT you never save them.

For example, in the showMenu you return an integer.

Then doing this - showMenu(menuSelection); Isint enough. You have to save it, in and in this case in a integer variable -
int saveMenu= showMenu(menuSelection);

And then now whatever integer the function returned is now stored in saveMenu and can be used for your switch statement -

switch (saveMenu)

[zT4NhbRD]

I did as you explained but it's still looping instead of running the switch statements.

Here's the updated code:

int main ()
{
cout.precision (2);
    double itemPrice = 0.0, totalCost=0.0;
    //initialize function variables
    menuSelection;
    double price, runningTotal, givenDiscount; 
    int saveMenu = showMenu(menuSelection);
    //initialize functions
    double getDiscountRate(double discountRate);
    double getPrice(double itemPrice, double totalCost);
    void printReceipt(double totalCost, double discountRate);
    int showMenu(int choice);


   
    do {
         showMenu(menuSelection);
         switch (saveMenu)
         {
             case SCAN_ITEM:
                  getPrice (price, runningTotal);                 
                  break;
             case DISCOUNT:
                  getDiscountRate(givenDiscount);
                  break;
             case RECEIPT:
                  printReceipt(runningTotal, givenDiscount);         
                  break;
             case EXIT:
                  printReceipt(runningTotal, givenDiscount);
                  cout << "System Exit\n" << endl;
                  break;
         }
    } while (saveMenu != EXIT);
    system ("pause");
    return 0;
}
//Functions
int showMenu(int choice)
{
    cout << "Supermarket POS System\n"
         << "----------------------------------\n"
         << "Select an option:\n"
         << SCAN_ITEM << ". Scan an Item\n"
         << DISCOUNT << ". Set Discount Rate\n"
         << RECEIPT << ". Print Receipt\n"
         << EXIT << ". Exit\n"
         << "\n >>";
    cin  >> choice;
    return (choice);
}
double getPrice(double itemPrice, double totalCost)
{
    do {
         cout << "Enter the item price (positive number only): ";
         cin >> itemPrice;
         if (itemPrice <= 0) {
             cout << "Please enter a positive number only.\n" << endl;
         }
         else {
         totalCost += itemPrice;
         cout << "Running Total: " << fixed << totalCost << "\n" << endl;
         }
    } while (itemPrice <= 0);
    return (totalCost);
}
double getDiscountRate(double discountRate)
{
    cout << "Enter the Discount Rate (0.0-1.0): ";
    cin >> discountRate;
    cout << "Customer discount is at " << discountRate*100 <<"% off.\n" << endl;
    return (discountRate);
}
void printReceipt(double totalCost, double discountRate)
{
    double discountTotal, taxTotal;
    discountTotal = totalCost*discountRate;
    taxTotal = (totalCost-discountTotal)*TAX;
    cout << "Total Purchase:\t " << setw(8) << totalCost << "\n";
    if (discountRate > 0) {
    cout << "Discount:\t" << "-" << setw(8) << discountTotal << "\n";
    }
    cout << "Tax:\t\t" << "+" << setw(8) << taxTotal << "\n";
    cout << "Total Charge:\t" << "=" << setw(8) <<totalCost - discountTotal + taxTotal << "\n" << endl;
}

[TarikNeaj]

Thats kinda not what I said. Just do this between your Do loop and switch statement, Nothing else - int saveMenu= showMenu(menuSelection); This will save the integer and display the menu.

//initialize function variables
    menuSelection;

No idea what that is suppose to be. You're not initializing anything. So you can remove that one.

Also remove this - int saveMenu = showMenu(menuSelection);

Edit: Where you initialize variables. Create "int choice = 0;" And send that one in instead of menuSelection, so it looks like this - int saveMenu= showMenu(choice)

[zT4NhbRD]

Now it's telling me that saveMenu is undeclared in my while statement and the loop won't break when I put in exit.

[TarikNeaj]

Why is it outside your do brackets? I specifically told you -

Just do this between your Do loop and switch statement, Nothing else - int saveMenu= showMenu(menuSelection);

Between your Do loop and switch statement is inside your do brackets...

[zT4NhbRD]

Uh, I did put it inside the do brackets, if you read my post I said the problem is my while statement. The loop will not break unless I input the EXIT choice twice.

[TarikNeaj]

Sorry about that. Just use a boolean. You can create a

bool ok = true;

Then run the loop while(ok != false)

Then you can set "ok" to false in one of the cases, Im guessing the exit one.

Or you could just use return 0;

Also, you dont want the system("pause"); one there. You want the program to shut down instantly after the loops breaks, not wait for further input.

[zT4NhbRD]

Got it, thanks for all the help and for all your patience. :)

[TarikNeaj]

Glad to help :) goodluck to you.

[zT4NhbRD]

So I got points docked off for using the wrong boolean loop termination. It says I should've put (saveMenu != EXIT). Problem is that whenever I try to run the program after applying that fix the program won't even compile because saveMenu is not defined outside outside of the do brackets. Then when I try to run it after defining saveMenu outside of it my program just crashes.

Any ideas?