Solution to Programming Assignment 2a

////
//
// This program makes change, given an amount of purchase and an amount
// tendered.  The ouput is a total amount of change, followed by change in
// eight demoninations of money: twenties, tens, fives, dollars, quarters,
// dimes, nickels, and pennies.  Both inputs are in dollars and decimal cents,
// e.g., 3.16 or .25.  Output of the total change is in dollars and decimal
// cents, rounded to the nearest cent and printed always with exactly two
// places to the right of the decimal point, e.g., 1.84 or 0.10.  Output of the
// change for each denomination is in whole numbers of that denomination.
//
// Author: Gene Fisher (gfisher@calpoly.edu)
// Created: 14apr99
// Modified: 14apr99
//
////

#include <iostream.h>
#include <iomanip.h>


int main() {

    //
    // Declare program variables to hold the purchase amount, amount tendered,
    // total change amount, and the amounts of each denomination of change,
    // from dollars to pennies.
    //
    float purchase;                     // Amount of purchase
    float tendered;                     // Amount tendered
    float change;                       // Total change due
    int change_in_cents;                // Total change due, in whole pennies
    int twenties;                       // Number of twenties  in change
    int tens;                           //   "    "  tens      "    "
    int fives;                          //   "    "  fives     "    "
    int dollars;                        //   "    "  dollars   "    "
    int quarters;                       //   "    "  quarters  "    "
    int dimes;                          //   "    "  dimes     "    "
    int nickels;                        //   "    "  nickels   "    "
    int pennies;                        //   "    "  pennnies  "    "

    //
    // Set up floating point output format always to print decimal point and
    // not to use scientific notation.
    //
    cout.setf(ios::fixed, ios::floatfield);
    cout.setf(ios::showpoint);

    //
    // Prompt the user for the amount of purchase.
    //
    cout << "Input the amount of the purchase, in dollars and cents: ";

    //
    // Input the amount of purchase.
    //
    cin >> purchase;

    //
    // Prompt for the amount tendered.
    //
    cout << "Input the amount tendered, in dollars and cents: ";

    //
    // Input the amount tendered.
    //
    cin >> tendered;

    //
    // Output a blank line, for nice formatting.
    //
    cout << endl;

    //
    // Compute the total amount of change due, in dollars and cents.  Assume
    // that this value is non-negative.
    //
    change = tendered - purchase;

    //
    // Output the total change amount, followed by a blank line.  Note the use
    // of setprecision to print exactly two places after the decimal point.
    //
    cout << "Total change due = " << setprecision(2) << change << endl
         << endl;

    //
    // Convert the total change in dollars and cents into whole number of
    // cents.  Note the rounding, which avoids round-off error that might
    // result in floating point value.  E.g., 3.14 in change might actually be
    // represented as 3.1399999 in the floating point value of the change
    // variable in computer memory.
    //
    change_in_cents = int (100 * (change + 0.005));

    //
    // Compute the number of twenties in change by dividing the total change by
    // 2000.
    //
    twenties = change_in_cents / 2000;

    //
    // Compute the remaining amount of change by subtracting the amount of
    // change in twenties from the total change.
    //
    change_in_cents = change_in_cents - (twenties * 2000);

    //
    // Proceed in the same way as for twenties with the remaining
    // denominations.
    //
    tens = change_in_cents / 1000;
    change_in_cents = change_in_cents - (tens * 1000);
    fives = change_in_cents / 500;
    change_in_cents = change_in_cents - (fives * 500);
    dollars = change_in_cents / 100;
    change_in_cents = change_in_cents - (dollars * 100);
    quarters = change_in_cents / 25;
    change_in_cents = change_in_cents - (quarters * 25);
    dimes = change_in_cents / 10;
    change_in_cents = change_in_cents - (dimes * 10);
    nickels = change_in_cents / 5;
    pennies = change_in_cents - (nickels * 5);

    //
    // Output the results of the pieces of change computations.
    //
    cout << "Change in twenties through pennies is:" << endl
         << "    " << twenties << " twenties" << endl
         << "    " << tens << " tens" << endl
         << "    " << fives << " fives" << endl
         << "    " << dollars << " dollars" << endl
         << "    " << quarters << " quarters" << endl
         << "    " << dimes << " dimes" << endl
         << "    " << nickels << " nickels" << endl
         << "    " << pennies << " pennies" << endl << endl;

    return 0;
}