money class 1.1

Bjarne Stroustrup “Programming Principles and Practice Using C++”
Chapter 9 Exercise 15
Using std_lib_facilities.h by Bjarne Stroustrup.

[code language=”cpp”]
// Philipp Siedler
// Bjarne Stroustrup’s PPP
// Chapter 9 Exercise 15

#include "std_lib_facilities.h"

enum currency {
USD, EUR, GBP
};

ostream & operator<<(ostream & os, currency & c) {
if (c == USD) {
os << "USD";
return os;
}
if (c == EUR) {
os << "EUR";
return os;
}
if (c == GBP) {
os << "GBP";
return os;
}
}

class Money {
public:
long int amount;
currency cur;

//constructors
Money();
Money(double);
Money(currency, double);

//non-modifying operations
long int get_amount() { return amount; }
double get_amount_decimal();
void read_value(bool&, currency&, double&);
void print() { cout << cur << get_amount_decimal() << endl; }

//modifying operations
};

Money::Money() {
amount = 0;
cur = USD;
}

Money::Money(double a) {
double temp_d0 = a;
temp_d0 *= 100;
int temp_i = (int)temp_d0;
double difference = temp_d0 – temp_i;
if (difference >= 0.5) {
temp_i++;
}
amount = temp_i;
cur = USD;
}

Money::Money(currency c, double a) {
double temp_d0 = a;
temp_d0 *= 100;
int temp_i = (int)temp_d0;
double difference = temp_d0 – temp_i;
if (difference >= 0.5) {
temp_i++;
}
amount = temp_i;
cur = c;
}

double Money::get_amount_decimal() {
return double(amount) / 100;
}

void read_value(currency & c, double& i) {
string cur;
char l;
double amount;

while (true) {
cin >> l;
if (isalpha(l)) {
cur += l;
}
else {
if (cur == "USD" || cur == "EUR" || cur == "GBP") {
if (cur == "USD") {
c = currency::USD;
}
else if (cur == "EUR") {
c = currency::EUR;
}
else if (cur == "GBP") {
c = currency::GBP;
}
}
else {
cout << "Invalid currency" << cur << endl;
break;
}

cin.putback(l);
cin >> amount;

i = amount;
break;
}
}
}

double EURtoUSD(double d) {
return d * 1.12;
}

double GBPtoUSD(double d) {
return d * 1.26;
}

double USDtoEUR(double d) {
return d * 0.89;
}

double GBPtoEUR(double d) {
return d * 1.13;
}

double USDtoGBP(double d) {
return d * 0.78;
}

double EURtoGBP(double d) {
return d * 0.88;
}

Money operator+(Money & m1, Money & m2) {

switch (m1.cur) {
case USD:{
switch (m2.cur) {
case USD: {return Money(USD, m1.get_amount_decimal() + m2.get_amount_decimal()); }
case EUR: {return Money(USD, m1.get_amount_decimal() + EURtoUSD(m2.get_amount_decimal())); }
case GBP: {return Money(USD, m1.get_amount_decimal() + GBPtoUSD(m2.get_amount_decimal())); }
}
}
case EUR:{
switch (m2.cur) {
case USD: {return Money(m1.get_amount_decimal() + USDtoEUR(m2.get_amount_decimal())); }
case EUR: {return Money(m1.get_amount_decimal() + m2.get_amount_decimal()); }
case GBP: {return Money(m1.get_amount_decimal() + GBPtoEUR(m2.get_amount_decimal())); }
}
}
case GBP:{
switch (m2.cur) {
case USD: {return Money(GBP, m1.get_amount_decimal() + USDtoGBP(m2.get_amount_decimal())); }
case EUR: {return Money(GBP, m1.get_amount_decimal() + EURtoGBP(m2.get_amount_decimal())); }
case GBP: {return Money(GBP, m1.get_amount_decimal() + m2.get_amount_decimal()); }
}
}
}

}

void calculate() {

double input1;
currency cur1;
double input2;
currency cur2;

cout << "Enter first set of money as float: " << endl;
cout << "Supported currencies: EUR, GBP, USD," << endl;
cout << "Format example: USD 12.235" << endl;
read_value(cur1, input1);
Money money1(cur1, input1);
money1.print();

cout << "Enter second set of money as float: " << endl;
cout << "Supported currencies: EUR, GBP, USD," << endl;
cout << "Format example: USD 12.235" << endl;

read_value(cur2, input2);
Money money2(cur2, input2);
money2.print();

Money money3 = money1 + money2;
cout << "money1 + money2 = ";
money3.print();
}

int main()
try
{
calculate();
keep_window_open();
}

catch (runtime_error e) {
cout << e.what() << endl;
keep_window_open();
}
catch (…) {
cout << "Exiting" << endl;
keep_window_open();
}
[/code]

Output:
Enter first set of money as float:
Supported currencies: EUR, GBP, USD,
Format example: USD 12.235
GBP 23.456
GBP23.46
Enter second set of money as float:
Supported currencies: EUR, GBP, USD,
Format example: USD 12.235
USD 50.235
USD50.24
money1 + money2 = GBP62.65
Please enter a character to exit