Question

Modify the provided code to create a program that calculates the amount of change given to a customer based on their total. The program prompts the user to enter an item choice, quantity, and payment amount.

Use three functions:

• bool isValidChoice(char) – Takes the user choice as an argument, and returns true if it is a valid selection. Otherwise it returns false.

• float calcTotal(int, float) – Takes the item cost and the quantity as arguments. Calculates the subtotal, and returns the grand total with sales tax (8.25%).

• float calcChange(float, float) – Takes total and the amount paid and returns the change. Amount paid must be higher than the total.

IMPORTANT!

• The functions should not print any value. All the values are printed from the main function.

• Do not modify the main function. Write the functions such that they work in the code provided

Sample Output:

Welcome to the Vend-o-matic! Here are your choices:

a) Ice Cream - $2.75

b) Candy - $1.25

c) Soda - $1.50

d) Gum - $0.50

Please select an item:

b Enter Quantity: -1

ERROR: Invalid Quantity. Please reenter: 2

Total with tax: $2.71

Enter Payment Amount: $2.00

ERROR: Insufficient funds. Please reenter payment: $3.00

Your change due is: $.29

_____________________________________________________________________

#include <iostream>
#include <iomanip>
using namespace std;

// Function Prototypes:
bool isValidChoice(char);
float calcTotal(int, float);
float calcChange(float, float);

int main()
{
char choice;
int quantity;
float total, payment_amount, change, item_cost;

cout << "Welcome to the Vend-o-matic! Here are your choices:" << endl
<< "a)Ice Cream - $2.75" << endl
<< "b)Candy - $1.25" << endl
<< "c)Soda - $1.50" << endl
<< "d)Gum - $0.50" << endl
<< "Please select an item: ";
cin >> choice;
while(!isValidChoice(choice)) // Function Call
{
cout << "Error: Invalid choice. Please select a valid item: ";
cin >> choice;
}

if(choice == 'a')
{
item_cost = 2.75;
}
else if(choice == 'b')
{
item_cost = 1.25;
}
else if(choice == 'c')
{
item_cost = 1.50;
}
else if(choice == 'd')
{
item_cost = 0.50;
}

cout << endl << "Enter Quantity: ";
cin >> quantity;

while(quantity < 1 || quantity > 20)
{
cout << "ERROR: Invalid Quantity. Please re-enter: ";
cin >> quantity;
}

total = calcTotal(quantity, item_cost); // Function Call

cout << fixed << setprecision(2) << "Total with tax: $" << total << endl;

cout << "Enter Payment Amount: $";
cin >> payment_amount;

while(payment_amount < total)
{
cout << "ERROR: Insufficient funds. Please re-enter payment: $";
cin >> payment_amount;
}

change = calcChange(total, payment_amount); // Function Call

cout << "Your change is: $" << change;

return 0;
}

// TODO: add function definitions here

Answer 1

#include <iostream>
#include <iomanip>
using namespace std;

// Function Prototypes:
bool isValidChoice(char);
float calcTotal(int, float);
float calcChange(float, float);

int main()
{
    char choice;
    int quantity;
    float total, payment_amount, change, item_cost;

    cout << "Welcome to the Vend-o-matic! Here are your choices:" << endl
    << "a)Ice Cream - $2.75" << endl
    << "b)Candy - $1.25" << endl
    << "c)Soda - $1.50" << endl
    << "d)Gum - $0.50" << endl
    << "Please select an item: ";
    cin >> choice;
   
    while(!isValidChoice(choice)) // Function Call
    {
    cout << "Error: Invalid choice. Please select a valid item: ";
    cin >> choice;
    }

    if(choice == 'a')
    {
        item_cost = 2.75;
    }
    else if(choice == 'b')
    {
        item_cost = 1.25;
    }
    else if(choice == 'c')
    {
        item_cost = 1.50;
    }
    else if(choice == 'd')
    {
        item_cost = 0.50;
    }

    cout << "Enter Quantity: ";
    cin >> quantity;

    while(quantity < 1 || quantity > 20)
    {
        cout << "ERROR: Invalid Quantity. Please re-enter: ";
        cin >> quantity;
    }

    total = calcTotal(quantity, item_cost); // Function Call

    cout << fixed << setprecision(2) << "Total with tax: $" << total << endl;

    cout << "Enter Payment Amount: $";
    cin >> payment_amount;

    while(payment_amount < total)
    {
    cout << "ERROR: Insufficient funds. Please re-enter payment: $";
    cin >> payment_amount;
    }

    change = calcChange(total, payment_amount); // Function Call

    cout << "Your change due is: $" << change;

    return 0;
}

bool isValidChoice(char ch){
    
    //checks if ch is equal to a,b,c,d then rreturns true
    //otherwise returns false
    if(ch == 'a' || ch == 'b' || ch == 'c' || ch == 'd'){
        
        return true;
    }
    else{
        return false;
    }
}

float calcTotal(int qty, float cost){
    
    //multiply qty with cost and store it in temp variable
    float temp = qty * cost;
    
    //calculates 8.25% sales tac
    float tax =  (qty * cost *8.25)/100;
    
    //calculates final amout with tax and store it in ans variable
    float ans = temp + tax;
    
    //return ans
    return ans;
    
}

float calcChange(float total, float payable_amt){
    
    //calculates change amount
    float change = payable_amt - total;
    
    //return change
    return change;
}

OUTPUT: