/* Program for water bill problem with conservation guidelines */
/*
* Computes and prints a water bill given an unpaid balance and previous and
* current meter readings. Bill includes a demand charge of $35.00, a use
* charge of $1.10 per thousand gallons, and a surcharge of $2.00 if there is
* an unpaid balance.
*/
#include <stdio.h>
#define DEMAND_CHG 35.00 /* basic water demand charge */
#define PER_1000_CHG 1.10 /* charge per thousand gallons used */
#define LATE_CHG 2.00 /* surcharge assessed on unpaid balance */
#define OVERUSE_CHG_RATE 2.0 /* double use charge as non-conservation penalty */
#define CONSERV_RATE 95 /* percent of last year's use allowed this year */
/*
* Displays user instructions
*/
void
instruct_water(void)
{
printf("This program figures a water bill ");
printf("based on the demand charge\n");
printf("($%.2lf) and a $%.2lf per 1000 ", DEMAND_CHG, PER_1000_CHG);
printf("gallons use charge.\n\n");
printf("A $%.2lf surcharge is added to ", LATE_CHG);
printf("accounts with an unpaid balance.\n");
printf("\nEnter unpaid balance, previous ");
printf("and current meter readings\n");
printf("on separate lines after the prompts.\n");
printf("Press or after ");
printf("typing each number.\n\n");
}
/*
* Computes use charge with conservation requirements
* Pre: previous, current, and use_last_year are defined.
*/
double
comp_use_charge(int previous, int current, int use_last_year)
{
int used; /* gallons of water used (in thousands) */
double use_charge; /* charge for actual water use */
used = current - previous;
if (used <= CONSERV_RATE / 100.0 * use_last_year) {
/* conservation guidelines met */
use_charge = used * PER_1000_CHG;
} else {
printf("Use charge is at %.2lf times ", OVERUSE_CHG_RATE);
printf("normal rate since use of\n");
printf("%d units exceeds %d percent ", used, CONSERV_RATE);
printf("of last year's %d-unit use.\n", use_last_year);
use_charge = used * OVERUSE_CHG_RATE * PER_1000_CHG;
}
return (use_charge);
}
/*
* Computes late charge.
* Pre : unpaid is defined.
*/
double
comp_late_charge(double unpaid)
{
double late_charge; /* charge for nonpayment of part of previous balance */
if (unpaid > 0)
late_charge = LATE_CHG; /* Assess late charge on unpaid balance. */
else
late_charge = 0.0;
return (late_charge);
}
/*
* Displays late charge if any and bill.
* Pre : late_charge, bill, and unpaid are defined.
*/
void
display_bill(double late_charge, double bill, double unpaid)
{
if (late_charge > 0.0) {
printf("\nBill includes $%.2lf late charge", late_charge);
printf(" on unpaid balance of $%.2lf\n", unpaid);
}
printf("\nTotal due = $%.2lf\n", bill);
}
int
main(void)
{
int previous; /* input - meter reading from previous quarter
in thousands of gallons */
int current; /* input - meter reading from current quarter */
int use_last_year; /* last year usage */
double unpaid; /* input - unpaid balance of previous bill */
double bill; /* output - water bill */
int used; /* thousands of gallons used this quarter */
double use_charge; /* charge for actual water use */
double late_charge; /* charge for nonpayment of part of previous
balance */
/* Display user instructions. */
instruct_water();
/* Get data: unpaid balance, previous and current meter
readings. */
printf("Enter unpaid balance > $");
scanf("%lf", &unpaid);
printf("Enter previous meter reading > ");
scanf("%d", &previous);
printf("Enter current meter reading > ");
scanf("%d", ¤t);
printf("Enter last year's reading > ");
scanf("%d", &use_last_year);
/* Compute use charge. */
use_charge = comp_use_charge(previous, current, use_last_year);
/* Determine applicable late charge */
late_charge = comp_late_charge(unpaid);
/* Figure bill. */
bill = DEMAND_CHG + use_charge + unpaid + late_charge;
/* Print bill. */
display_bill(late_charge, bill, unpaid);
return (0);
}
