My c++ program will not add up my total prices - c++

Question

I'm new to programing and I'm trying to get this program to add up a price of coffee to the add on extras such as cinnamon, etc. But once the program runs it doesn't add up the coffee price with the extras and I've been at it for hours and I'm stumped. Like I said I'm new to this so if someone can help and explain why its not working or what I need to fix that would be great. Thank you!
Code:
#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{
const int SIZE = 5;
double COFFEEPRICE = 2.00;
string products[SIZE]= {"Whipped cream", "Cinnamon", "Chocolate sauce", "Amaretto", "Irish whiskey"};
double prices[SIZE]={0.89, 0.25, 0.59, 1.50, 1.75};
int totalPrice = 0;
int choice = 0;
int SENTINEL = -1;
{
while (choice <= SENTINEL)
cout << "Please select an item from the Product menu by selecting the item number (1 - 5) or -1 to terminate: " ;
cout << "Product Price ($)" << endl;
cout << "======= =========" << endl;
cout << "1. Whipped cream 0.89" << endl;
cout << "2. Cinnamon 0.25" << endl;
cout << "3. Chocolate sauce 0.89" << endl;
cout << "4. Amaretto 1.50" << endl;
cout << "5. Irish whiskey 1.75" << endl;
cout << "Please enter a positive number: " << endl;
cin >> choice;
if (choice > SENTINEL)
{
if ((choice >= 1) && (choice <= 5))
{
totalPrice = totalPrice + prices[choice-1];
cout << "Item number " << choice << ": "<< products[choice-1] << " has been added" << endl;
}
else
{
cout << "Item number ",choice, " is not valid", "Sorry we do not carry that item" ;
}
}
totalPrice + COFFEEPRICE;
cout << "Total price of order is $" << totalPrice << endl;
cout << "Thanks for purchasing from Jumpin Jive Coffee Shop" << endl;
}
system("pause");
return 0;
}

Answer 1

You have to assign new price, which is
totalPrice + COFFEEPRICE
to the old value. So write:
totalPrice = totalPrice + COFFEEPRICE; // note,
// same as totalPrice += COFFEEPRICE;
Otherwise, the expression totalPrice + COFFEEPRICE; does nothing useful.
Also, I wonder how this work for you (this won't get into while(): probably just for debugging?):
int choice = 0;
int SENTINEL = -1;
{
while (choice <= SENTINEL)

Answer 2

You need to change
totalPrice + COFFEEPRICE; // Problem: totalPrice will not change!!!
to
totalPrice = totalPrice + COFFEEPRICE; // add and update by assign back
or
totalPrice += COFFEEPRICE; // equivalent to the above
in order to update totalPrice with the new added value.

Answer 3

Found too many error so instead of pointing each one...I have made changes and posted the correct code...
First and major one will be loop...
You havn't got any input from user and checking whether he wants to quit(by entering negative number)...way you have use while loop is not correct...
do while made more sense here....also total totalPrice + COFFEEPRICE; You need to store this value somewhere so that you can use it again
double totalPrice;
totalPrice = totalPrice + COFFEEPRICE;
#include <iostream>
#include <cstdlib>
using namespace std;
int main()
{
const int SIZE = 5;
double COFFEEPRICE = 2.00;
string products[SIZE]= {"Whipped cream", "Cinnamon", "Chocolate sauce", "Amaretto", "Irish whiskey"};
double prices[SIZE]={0.89, 0.25, 0.59, 1.50, 1.75};
double totalPrice = 0;
int choice = 0;
int SENTINEL = -1;
do
{
cout << "Please select an item from the Product menu by selecting the item number (1 - 5) or -1 to terminate: " ;
cout << "Product Price ($)" << endl;
cout << "======= =========" << endl;
cout << "1. Whipped cream 0.89" << endl;
cout << "2. Cinnamon 0.25" << endl;
cout << "3. Chocolate sauce 0.89" << endl;
cout << "4. Amaretto 1.50" << endl;
cout << "5. Irish whiskey 1.75" << endl;
cout << "Please enter a positive number: " << endl;
cin >> choice;
if (choice > SENTINEL)
{
if ((choice >= 1) && (choice <= 5))
{
totalPrice = totalPrice + prices[choice-1];
cout << "Item number " << choice << ": "<< products[choice-1] << " has been added" << endl;
}
else
{
cout << "Item number ",choice, " is not valid", "Sorry we do not carry that item" ;
}
}
totalPrice = totalPrice + COFFEEPRICE;
cout << "Total price of order is $" << totalPrice << endl;
cout << "Thanks for purchasing from Jumpin Jive Coffee Shop" << endl;
}while (choice <= SENTINEL);
//system("pause");
return 0;
}