How to display differences in prices using switch statements in C++ - c++

Question

For a class project I have to develop a program that calculates the cost of a mobile device service. There are 3 packages the user can choose from. The cost of the service is determined by the base price and number of message units to be used. After the user chooses a package I have to let them know the price of the package as well as letting them know if either of the other packages would be cheaper and show what the difference in price would be by using switch statements. I've wrote some switch statements comparing the packages, but how do I show and calculate how much they would save if there is a cheaper package than the one chosen? I am also a beginner so take it easy.
int main() {
bool finished = false;
do {
// to keep it simple
double choice_a = 9.95;
double choice_b = 19.95;
double choice_c = 39.95;
char choice;
int message_units;
double price;
bool selected = false;
// this loop shows the options initially
do {
cout << "Which package do you choose (enter A, B or C)" << endl;
// you will need to check this
cin >> choice;
// keeping it simple
if (choice == 'A') { price = choice_a; selected = true; }
else if (choice == 'B') { price = choice_b; selected = true; }
else if (choice == 'C') { price = choice_c; selected = true; }
cout << endl;
}
// loops until something was selected
while (selected == false);
// user enters how many units is wanted
cout << "How many message units (enter 1 - 672)" << endl;
// again check this (if homework requires checking input)
cin >> message_units;
// Calculating message units
if(message_units > 5){
price += 100 * (message_units - 5);
}
if(message_units > 15){
price += 50 * (message_units - 15);
}
// Total Price Output
cout << "Your total cost is " << price/100 << endl
// Is user done?
char done;
cout << "Do you want to enter another? press enter to continue.
cin >> done;
// check
if (done != ' ') {
finished = true;
}
}
while (finished = false);
}
switch (choice)
{
case 'A':
if(choice_b < choice_a);
cout << "You can save by switching to package B" << endl;
else if(choice_c < choice_a);
cout << "You can save by switching to package C" << endl;
break;
case 'B':
if(choice_a < choice_b);
cout << "You can save by switching to package A" << endl;
else if(choice_c < choice_b);
cout << "You can save by switching to package C" << endl;
break;
case 'C':
if(choice_a < choice_c);
cout << "You can save by switching to package A" << endl;
else if(choice_b < choice_c);
cout << "You can save by switching to package B" << endl;
break;
}

Answer 1

#include <iostream>
using namespace std;
int main() {
bool finished = false;
char choice;
double choice_a = 9.95;
double choice_b = 19.95;
double choice_c = 39.95;
int message_units;
double price;
bool selected = false;
do {
// to keep it simple
// this loop shows the options initially
do {
cout << "Which package do you choose (enter A, B or C)" << endl;
// you will need to check this
cin >> choice;
// keeping it simple
if (choice == 'A') { price = choice_a; selected = true; }
else if (choice == 'B') { price = choice_b; selected = true; }
else if (choice == 'C') { price = choice_c; selected = true; }
cout << endl;
}
// loops until something was selected
while (selected == false);
// user enters how many units is wanted
cout << "How many message units (enter 1 - 672)" << endl;
// again check this (if homework requires checking input)
cin >> message_units;
// Calculating message units
if(message_units > 5){
price += 100 * (message_units - 5);
}
if(message_units > 15){
price += 50 * (message_units - 15);
}
// Total Price Output
cout << "Your total cost is " << price/100 << endl;
switch (choice)
{
case 'A':
if(choice_b < choice_a)
cout << "you can save by switching to package B it saves: " << choice_a - choice_b << " if you choose B" << endl;
else if(choice_c < choice_a)
cout << "You can save by switching to package C is saves: " << choice_a - choice_c << endl;
break;
case 'B':
if(choice_a < choice_b)
cout << "you can save by switching to package A it saves: " << choice_b - choice_a << " if you choose a" << endl;
else if(choice_c < choice_b)
cout << "you can save by switching to package C it saves: " << choice_b - choice_c << " if you choose c" << endl;
break;
case 'C':
if(choice_a < choice_c)
cout << "you can save by switching to package A it saves: " << choice_c - choice_a << " if you choose a" << endl;
else if(choice_b < choice_c)
cout << "you can save by switching to package A it saves: " << choice_c - choice_b << " if you choose b" << endl;
break;
}
// Is user done?
char done;
cout << "Do you want to enter another? press enter to continue.";
cin >> done;
// check
if (done != ' ') {
finished = true;
}
}
while (finished == false);
}
sorry for not explaining but i try explaining it the best i can
based on your code. i fix some wrong syntaxe and tries to match the problem
you've post so i defined all the variables you've created outside the first
outer bool so that the switch statement will work and i edit some code in the switch statement to calculate the amount of savings and displays them based on the conditions sorry for bad english.

Answer 2

Assuming you are comparing the two with the same quantity,
Savings = [(Selection Price) - (Cheaper Option Price)]× Quantity
If you do this calculation and say assign it to a type double called Savings, you can print this out.
cout << "Savings are "<< Savings;
Doing this on each if statement is simple, but of course there are better ways to do this. Such as calling a function that does this simple calculation for two options.
EDIT 1: Apologize for the poor formatting, this is on my phone.
EDIT 2: Also noticed you have incorrect syntax with your control loops. Here is a good resource here
EDIT 3: There are actually a number of other issues including your switch statement being outside of main.
This line doesn't make sense, in practical terms.
// Calculating message units if(message_units > 5){ price += 100 * (message_units - 5); } if(message_units > 15){ price += 50 * (message_units - 15); }
Good practice would suggest not overwriting a variable with a value with a different meaning. It is confusing. Initially it seems price is the per quantity price. Then it looks like you try to assign the overall cost to it.
(I'm assuming; it doesn't actually do this. Instead it adds a price of 100 per unit except for the first 5 to a single unit price you declare at the top. Similarly for the greater than 15 block.)
EDIT 4: Per request in comments:
If I am correct in what I think you are trying to do, replace this block:
// Calculating message units
if(message_units > 5){
price += 100 * (message_units - 5);
}
if(message_units > 15){
price += 50 * (message_units - 15);
}
with:
double Total_Cost;
if(message_units => 5 && message_units<15){
Total_Cost = price * (message_units - 5);
}
else if(message_units => 15){
Total_Cost = price * (message_units - 15);
}
else{
Total_Cost = price * message_units;
}
That is 'you get the first 5 free (or 15) if you buy in bulk'. Otherwise it is just the price times the number of units. This again seems kind of strange, but this is what this does.