//Program to demonstrate the class Money in Display 8.6. 
#include <iostream.h>
#include <stdlib.h>
#include <ctype.h>

const int FALSE = 0;
const int TRUE = 1;

//Class for amounts of money in U.S. currency. 
class Money
{
public:
    friend Money operator +(const Money& amount1, const Money& amount2);

    friend Money operator -(const Money& amount1, const Money& amount2);
    //Precondition: amount1 and amount2 have been given values.
    //Returns amount 1 minus amount2.

    friend Money operator -(const Money& amount);
    //Precondition: amount has been given a value.
    //Returns the negative of the value of amount.

    friend int operator ==(const Money& amount1, const Money& amount2);

    Money(long dollars, int cents);

    Money(long dollars);

    Money( );

    double get_value( ) const;

    void input(istream& ins);
    void output(ostream& outs) const;
private:
    long all_cents;
};

//Prototype for use in the definition of Money::input:
int digit_to_int(char c);
//Precondition: c is one of the digits '0' through '9'.
//Returns the integer for the digit; e.g., digit_to_int('3') returns 3.

//If your implementation does not include labs, then removed the 
//comments delimiters around the following prototype and around the 
//corresponding function definition, which is at the end of this file.
/*
long labs(long number);
//returns the absolute value of number.
*/

int main( )
{
    Money cost(1, 50), discount(0, 15), total, amount;
    total = cost - discount;

    cout << "cost = ";
    cost.output(cout);
    cout << endl;

    cout << "discount = ";
    discount.output(cout);
    cout << endl;
    cout << "total bill = ";
    total.output(cout);
    cout << endl;
    cout << "The discount changes the price by ";
    amount = -discount;
    amount.output(cout);
    cout << endl;
    return 0;
}

Money operator -(const Money& amount1, const Money& amount2)
{
    Money temp;
    temp.all_cents = amount1.all_cents - amount2.all_cents;
    return temp;
}

Money operator -(const Money& amount)
{
    Money temp;
    temp.all_cents = -amount.all_cents;
    return temp;
}

Money operator +(const Money& amount1, const Money& amount2)
{
    Money temp;
    temp.all_cents = amount1.all_cents + amount2.all_cents;
    return temp;
}

int operator ==(const Money& amount1, const Money& amount2)
{
    return (amount1.all_cents == amount2.all_cents);
}

Money::Money(long dollars, int cents)
{
    all_cents = dollars*100 + cents;
}

Money::Money(long dollars)
{
    all_cents = dollars*100;
}

Money::Money( )
{
    all_cents = 0;
}

double Money::get_value( ) const
{
    return (all_cents * 0.01);
}

//Uses iostream.h, ctype.h, stdlib.h, and constants TRUE and FALSE:
void Money::input(istream& ins)
{
    char one_char, decimal_point,
         digit1, digit2; //digits for the amount of cents
    long dollars;
    int cents,
        negative;//set to TRUE if input is negative.

    ins >> one_char;
    if (one_char == '-')
    {
        negative = TRUE;
        ins >> one_char; //read '$'
    }
    else
        negative = FALSE;
    //if input is legal, then one_char == '$'

    ins >> dollars >> decimal_point >> digit1 >> digit2;

    if ( one_char != '$' || decimal_point != '.'
         || !isdigit(digit1) || !isdigit(digit2) )
    {
        cout << "Error illegal form for money input\n";
        exit(1);
    }
    cents = digit_to_int(digit1)*10 + digit_to_int(digit2);

    all_cents = dollars*100 + cents;
    if (negative)
        all_cents = -all_cents;
}
//Uses stdlib.h and iostream.h:
void Money::output(ostream& outs) const
{
    long positive_cents, dollars, cents;
    positive_cents = labs(all_cents);
    dollars = positive_cents/100;
    cents = positive_cents%100;

    if (all_cents < 0)
        outs << "-$" << dollars << '.';
    else
        outs << "$" << dollars << '.';

    if (cents < 10)
        outs << '0';
    outs << cents;
}

int digit_to_int(char c)
{
    return ( int(c) - int('0') );
}

/*
long labs(long number)
{
    if (number < 0)
        return (-number);
    else
        return number;
}
*/