How to fix the calculation of tax yearly in a loop? - c++

Question

I need to write a program records membership fees for a Gym. The Gym charges a $1,200 per year, base fee but charges a percentage rate increase each year based on your membership rating:
Gold Members 1% fee
Silver Members 2% fee
Bronze Members 4% fee
It will display the following menu:
Welcome to Ronda’s Strikeforce Gym!!
x---------------------------------------------------x
Membership Fee Calculator
Gold
Silver
Bronze
Quit
Please enter your membership level (1-3 Enter 4 to Quit) >
The Validate input for the menu items listed, if 1 through 3 is entered, the program will use a loop to output the member's expected fees for the next 10 years. The output format is a table with the corresponding year and membership fee.
The program should continue to loop until the user is ready to quit. I am supposed to encapsulate the code in a do-while loop.
If a 4 is entered then the program should quit. Any other input should show an error message as output.
My output is not starting at the basevalue of 1200 but factors in the percentage. Upon another iteration of the program the last value calculated is used as a starting point.
This is what I have:
//Assignment 4-A.cpp: The program will calculate the membership fees over the next 10 years based on the membership level
#include <iostream>
#include <iomanip>
using namespace std;
int main() // Driver program
{
cout.setf(ios::fixed);
cout.setf(ios::showpoint);
cout.precision(2);
//To hold menu choice
const int GOLD = 1,
SILVER = 2,
BRONZE = 3,
QUIT = 4;
//To hold the percentage tax of the different gym choices
const double tax_gold = .01,
tax_silver = .02,
tax_bronze = .04;
//To hold the base charge per year
const double base_charge = 1200.00;
//variables
double fees = 0, cost = base_charge, cost_1 = 1200.00;
//To hold the users input
int user_input;
const int min_number = 1,
max_number = 10;
int i;
do
{
cout << "\t Welcome to Ronda's Strikeforce Gym!!" << endl; //Title
cout << "x";
for (int i = 0; i <= 50; i++) //Dashed line, row
{
cout << ("-");
}
cout << "x";
cout << endl;
cout << "\t Membership Fee Calculation" << endl; //Title
//Display of gym membership plan choice
cout << "1. Gold" << endl;
cout << "2. Silver" << endl;
cout << "3. Bronze" << endl;
cout << "4. Quit" << endl << "\n";
cout << "Please enter your membership level (1-3 Enter 4 to Quit) ";
cin >> user_input;
cout << endl;
// Validate user input(must input 1 through 4), loop if value is invalid
while (user_input < 1 || user_input > 4)
{
cout << "Invalid entry! ";
cout << "Please enter a selection from 1 through 4: ";
cin >> user_input;
cout << endl;
}
// If values 1 - 3 were entered perform calculations else if 4 was entered exit program with thank you message.
// Perform calculation for specified membership for 10 years and output
if (user_input == 4)
{
break;
}
if (user_input != QUIT)
{
//Start selection loop and calculation
switch (user_input)
{
case 1:
fees = base_charge * tax_gold;
cost = base_charge + fees;
break;
case 2:
fees = base_charge * tax_silver;
cost = base_charge + fees;
break;
case 3:
fees = base_charge * tax_bronze;
cost = base_charge + fees;
break;
}
//Display Yearly Cost
for (int years = 1; years <= 10; ++years)
{
cout << "Year " << years << "\t $" << (cost_1 += fees) << endl;
}
cout << "\n";
}
} while (user_input != QUIT);
{
cout << "Thank you for using Ronda's Fee Calculator! \n";
}
cout << endl;
cout << "Press any key to continue . . .";
return 0;
}
This is what shows on my computer:
enter image description here
and this is what it should look like:
enter image description here
Thank you

Answer 1

Your calculations should start with the base rate (cost = 1200). For each year, print the current rate then add rate * tax. (cost += cost * tax).
Here's your code with a few modifications:
//To hold menu choice
const int GOLD = 1, SILVER = 2, BRONZE = 3, QUIT = 4;
//To hold the percentage tax of the different gym choices
const std::array<double, 3> tax_rates{.01, .02, .04};
//To hold the base charge per year
const double base_charge = 1200.00;
while (true) {
cout << "\t Welcome to Ronda's Strikeforce Gym!!\nx"; //Title
for (int i = 0; i <= 50; i++) //Dashed line, row
{
cout << ("-");
}
cout << "x\n\t Membership Fee Calculation\n"; //Title
//Display of gym membership plan choice
cout << "1. Gold" << endl;
cout << "2. Silver" << endl;
cout << "3. Bronze" << endl;
cout << "4. Quit" << endl << "\n";
cout << "Please enter your membership level (1-3 Enter 4 to Quit) ";
int user_input;
cin >> user_input;
cout << endl;
// Validate user input(must input 1 through 4), loop if value is invalid
while (user_input < 1 || user_input > 4)
{
cout << "Invalid entry! ";
cout << "Please enter a selection from 1 through 4: ";
cin >> user_input;
cout << endl;
}
// If values 1 - 3 were entered perform calculations else if 4 was entered exit program with thank you message.
// Perform calculation for specified membership for 10 years and output
if (user_input == QUIT)
{
break;
}
//Display Yearly Cost
double cost = base_charge;
for (int years = 1; years <= 10; ++years)
{
cout << "Year " << years << "\t $" << cost << endl;
cost += cost * tax_rates[user_input-1];
}
cout << "\n";
}
cout << "Thank you for using Ronda's Fee Calculator!\n\nPress any key to continue . . .";
Side note: it is recommended that you don't use floating point values for currency. FP can introduce rounding errors. You can use integers in the base denomination of the currency. In US dollars that would be cents (pennies). Just something to note for future projects.