Question

1. Write a C++ program that allows a user choose item to purchase from a list; ask for the amount to calculate the cost of the purchase; offer to add a tip; add a delivery fee based on the subtotal; then calculate the total amount that the user needs to pay.

   ----------------------------------

   ----- GROCERY SHOPPING ITEMS -----

2. Milk     - $5.99 / gallon
3. Egg      - $6.99 / dozen
4. Cheese   – $10.98 / 8oz
5. Pasta    – $2.75 / packet

6. ----------------------------------

   Other Values to be used in the program.

   TIP (Optional) : $5.00

   SHIP_RATE1 (for $20 or below) : $0.00

   SHIP_RATE2 (for between $20 and $35): 4.35

   SHIP_RATE3 (for above #35) : 7.65

   Follow the Steps Below

7. The grocery list items and their prices are given above. You need to print it in the same format in your program. Use formatting output feature of the cout.
8. Ask the user to choose one of the items. Use the switch statement to evaluate user’s selection.
9. Ask the user to enter quantity of the chosen item. Then calculate the cost of the purchase.
10. Ask the user if he/she wants to pay a $5 tip. If the answer Yes, then add $5 to the cost; otherwise, keep the cost as it is. Use conditional formatting to code this.
11. Chek the subtotal. If it is less than or equal to $20.00, the shipping is free. If it is greater than $20.00 and less than or equal to $35.00, the shipping is $4.35. If it is greater than $35, then the shipping is $7.65. Based on the decision here calculate the total price that the user needs to pay.
12. Format the total price in fixed-point notation, with two decimal places of precision, and be sure the decimal point is always displayed.
13. Use functions to divide your program into manageable pieces. Define three functions: displayMenu, tipCalculator, and shippingCalculator.
    1. Write function prototypes at the top and define the functions after the main function.
14. displayMenu function:
    1. Move the code that displays the menu in the program into the function.
    2. Whenever you need to display the menu, call the function.
15. tipCalculator function:
    1. Move the code that asks users if they want to add a tip and calculate the subtotal accordingly, into the function.
    2. Call the function in an appropriate place in the main menu. Pass the value of subtotal to the function when calling. Return the value of new subtotal from the function.
    3. Write appropriate return type and parameter list for the function.
       Optional: You may ask the user how much money they would like to tip.
16. shippingCalculator function:
    1. Move the code that calculates the total including a shipping rate based on the subtotal, into the function.
    2. Call the function in an appropriate place in the main menu. Pass the value of subtotal to the function when calling. Return the value of shipping added total from the function.
    3. Write appropriate return type and parameter list for the function.
17. Define constants as global constants.
18. Keep variable definitions local.
19. At the beginning of the program display the menu, then ask the user if they want to give an order.
20. If the answer is no, exit the program with the exit() function.
21. Use while loop when the answer is yes in order to ask user if they want to give another order. Then, you can go through the process again and receive a new order. The subtotal will be accumulator of the while loop that keeps adding the cost of the new orders.
    The program should let user to give another order until they enter “no”.
22. Use do-while loop to check if the user’s item choice is valid. Display menu and ask user to make a valid choice until their choice is valid. If their choice is invalid, display a warning message. Once the choice is valid, you can terminate the loop and continue with the switch statement. (do-while loop will be used inside the while loop.)

Answer 1

Refer to the below code for the solution:

#include<bits/stdc++.h>
#include <iostream>
using namespace std;
 
// function declaration
string displayMenu();
float tipCalculator(float cost);
float shippingCalculator(float cost);

//declare global variable
const float m = 5.99;
const float e = 6.99;
const float c = 10.98;
const float p = 2.75;
const float SHIP_RATE1 = 0;
const float SHIP_RATE2 = 4.35;
const float SHIP_RATE3 = 7.65;

//enum and map for items
enum level {milk, egg, cheese, pasta};
map<string, level> items;
void register_items()
{
    items["milk"]   = milk;
    items["egg"] = egg;
    items["cheese"]   = cheese;
        items["pasta"] = pasta;
}

//function to change the case of a string
string change_case(string sl)
{
    transform(sl.begin(), sl.end(), sl.begin(), ::tolower);
    return sl;
}


int main () {
   // local variable declaration:
   string order;
   string input;
   float cost = 0;
   int quantity = 0;
   register_items();
   
   //fixed point notation for 2 decimal place precision
   std::cout.precision(2);

   //call function to display Menu
   order = displayMenu();
   while (!change_case(order).compare("yes"))
   {
       do{
           cout << "Enter the name of the item from the above list - ";
           cin >> input;
           input = change_case(input);
           switch(items[input])
           {
               case milk:
                    cost = cost + m;
                    break;
               case egg:
                    cost = cost + e;
                    break;
               case cheese:
                    cost = cost + c;
                    break;
               case pasta:
                    cost = cost + p;
                    break;
               default:
                    cout<<"Invalid input. Try again";
            }
         }while ( !(input.compare("milk") || input.compare("egg") || 
                  input.compare("cheese") || input.compare("pasta")));
         
        cout<<"Enter the quantity - ";
        cin>>quantity;
        cost = quantity * cost;
        order = displayMenu();
   }
   
    // calling a function to get cost
    if(cost != 0){
    cost = tipCalculator(cost);
    cost = shippingCalculator(cost);
    std::cout << "Total cost = " << std::fixed;
    std::cout <<cost;
    }
    return 0;
}

// function displaying menu
string displayMenu() {
   // local variable declaration
   string order;
 
   cout<<"----------------------------------\n";
   cout<<"----- GROCERY SHOPPING ITEMS -----\n";
   cout<<"Milk     - $5.99 / gallon\n";
   cout<<"Egg      - $6.99 / dozen\n";
   cout<<"Cheese   – $10.98 / 8oz\n";
   cout<<"Pasta    – $2.75 / packet\n";
   cout<<"----------------------------------\n\n";
   cout<<"Do you want to give a order? ";
   cin >> order;
   return order;
}

// function adding tip
float tipCalculator(float cost){
    
    string tip;
    cout<<"Do you want to give a tip? ";
    cin>>tip;
    if(!change_case(tip).compare("yes"))
    {
        cost = cost + 5;
    }
    return cost;
}

//function to calculate shipping
float shippingCalculator(float cost){
    
    if(cost<=20){
        cost = cost + SHIP_RATE1;
    }
    else if(cost>20 && cost<=35){
        cost = cost + SHIP_RATE2 ;
    }
    else if(cost>35){
        cost = cost + SHIP_RATE3 ;
    }
    return cost;

}

Snippet of running code:

OUTPUT 1:

OUTPUT 2:

OUTPUT 3: