I know one of the pointer benefit is that we can return more than one
value from a function . The down program has an error that I can not
discover . That is the call of the function :
The Call:
/*---------*/
weeks_rental ( & customer , & rentdue , &rent_per_we ek );
The Function:
/*---------*/
weeks_rental(cu st,due,re_per_w eek) /*---determine rent per week*/
/*------------------------------*/
struct customer_record *cust;
float *due;
float *re_per_week;
{
/*rent per week*/
switch ((*cust).tv_typ e)
{
case 'c':
*due=(*cust).no _of_weeks*3.60;
*re_per_week=(3 .60);
case 'b':
*due=(*cust).no _of_weeks*1.75;
*re_per_week=(1 .75);
case 'v':
*due=(*cust).no _of_weeks*1.50;
*re_per_week=(1 .50);
default :
printf("\n Program does not handle this type of rental\n");
return(0);
}
}
The Whole Program:
/*---------------*/
#include <stdio.h>
#include <stdlib.h>
/*TV rental system-Processing customer information from a
file-ver01-W*/
struct customer_record /*defining a customer record*/
{
int customer_no;
int no_of_weeks;
char tv_type;
};
main ()
{
struct customer_record customer;
FILE *fp_rent,*fp_su mm;
float rent_out;
float rent_per_week,r entdue;
/*1-open files-Old master(read),te mporary file(write)*/
/*---------------------------------------------------*/
if ((fp_rent=fopen ("setup.txt","r ")) == NULL)
{
printf("\nCan not open file 'setup.txt' for reading \n");
printf("Program is termainted");
exit(0);
}
if ((fp_summ=fopen ("summ.txt","w" )) == NULL)
{
printf("\nCan not open file 'summ' for writing \n");
printf("Program is termainted");
exit(0);
}
/*2-while not at end of file master file*/
/*--------------------------------------*/
do
{
/*2-1-read customers record from master file*/
/*-------------------------------------------*/
fscanf(fp_rent, "%4d%2d%c\n",&c ustomer.custome r_no,&customer. no_of_weeks,&cu stomer.tv_type) ;
/*
/*2-2-process bill*/
/*----------------*/
/*2-2-1 if not of file record*/
/*---------------------------*/
if (customer.custo mer_no!=9999)
{
/*2-2-1-1 determine rent due*/
/*--------------------------*/
weeks_rental ( & customer , & rentdue , &rent_per_we ek );
/*2-2-1-2 Converting dut to integer ready for output
to the file. At this stage rounding
errors
may occur,hence the addition of 0.005*/
/*---------------------------------------------*/
rent_out=(rentd ue+0.005)*100;
/*2-2-1-3 output information to summary file -
summ*/
/*-------------------------------------------------*/
fprintf(fp_summ ,"%4d %2d %c %6d\n",customer ,rent_out);
/*2-3-output customers bill on the screen for each record*/
/*--------------------------------------------------------*/
if (rent_per_week! =0)
print_bill(&cus tomer,rent_per_ week,rentdue);
}
/*2-End of while not at end of file master file*/
/*--------------------------------------*/
} while (customer.custo mer_no!=9999);
/*2-4-write customers bill information to temporary file-summ*/
/*-----------------------------------------------------------*/
fprintf(fp_summ ,"%4d %2d %c %6d\n",customer ,rent_out);
/*3-close files-masterfile-summ*/
/*-----------------------------*/
fclose(fp_rent) ;
fclose(fp_summ) ;
/*4-calculate and output summary table*/
/*summary();*/
}
weeks_rental(cu st,due,re_per_w eek) /*---determine rent per week*/
/*------------------------------*/
struct customer_record *cust;
float *due;
float *re_per_week;
{
/*rent per week*/
switch ((*cust).tv_typ e)
{
case 'c':
*due=(*cust).no _of_weeks*3.60;
*re_per_week=(3 .60);
case 'b':
*due=(*cust).no _of_weeks*1.75;
*re_per_week=(1 .75);
case 'v':
*due=(*cust).no _of_weeks*1.50;
*re_per_week=(1 .50);
default :
printf("\n Program does not handle this type of rental\n");
return(0);
}
}
print_bill(cust ,rent,due)
/*------------------------------------------------------------------------*/
struct customer_record *cust;
float rent;
float due;
{
int k;
/*printf("\n TV RENTAL BILL No %d :",k);*/
printf("\n TV Rental bill" );
printf("\n =============== =========");
printf("\n\n Customer number is %d",(*cust).cus tomer_no);
printf("\n Number of weeks rent due is %d",(*cust).no_ of_weeks);
printf("\n Rent per week is %.2f ",rent);
printf("\n\n Rental due is %.2f \n\n",due);
}
summary() /*produce summary report*/
/*----------*/
{
struct customer_record cust;
float total,rent_due;
int rent;
FILE *fp_summ; /*Decalres fp_summ as a file pointer*/
total=0; /*initital total*/
/*open file-summ for read*/
if ((fp_summ=fopen ("summ.txt","r" )) == NULL)
{
printf("\nCan not open file 'summ' for reading \n");
printf("Program is termainted");
exit(0);
}
/*print table heading*/
printf("\n\n SUMMARY REPORT ");
printf("\n _____________") ;
printf("\n\nCus tomer number Weeks due Rental type Rent due");
printf("\n--------------- --------- ----------- --------");
/*output summary table*/
do
{
/*read customer information from file summ*/
fscanf(fp_summ, "%4d %2d %c
%6d\n",&cust.cu stomer_no,&cust .no_of_weeks,&c ust.tv_type,&re nt);
/*If end of file customer number is 9999*/
if (cust.customer_ no!=9999)
{
/*Rent due was written to the file as an integer
therefore has to be converted back to a floating
point number*/
rent_due=rent/100.0;
/*print table of customer information*/
printf("\n %4d %2d %c
%6.2f",cust,ren t_due);
/*calcualte total rent due*/
total=total+ren t_due;
}
} while (cust.customer_ no!=9999);
/*close files*
fclose(fp_summ) ;
/*print total rent due*/
printf("\n\n Total rent due is %12.2f \n\n",total);
}
3  1518 
On 12 Jun 2005 07:57:15 -0700, eh**********@gm ail.com wrote: I know one of the pointer benefit is that we can return more than one
value from a function . The down program has an error that I can not
discover .
You forgot the breaks in the switch statement.
weeks_rental(c ust,due,re_per_ week) /*---determine rent per week*/
/*------------------------------*/
struct customer_record *cust;
float *due;
float *re_per_week;
{
/*rent per week*/
switch ((*cust).tv_typ e)
{
case 'c':
*due=(*cust).no _of_weeks*3.60;
*re_per_week=(3 .60);
break;
case 'b':
*due=(*cust).no _of_weeks*1.75;
*re_per_week=(1 .75);
break;
case 'v':
*due=(*cust).no _of_weeks*1.50;
*re_per_week=(1 .50);
break;
default :
printf("\n Program does not handle this type of rental\n");
return(0);
}
} eh**********@gm ail.com wrote: I know one of the pointer benefit is that we can return more than one
value from a function . The down program has an error that I can not
discover .
The most obvious error is in lines like fprintf(fp_summ ,"%4d %2d %c %6d\n",customer ,rent_out);
where customer is a struct. This obviously cannot work.
Your use of K&R-style function definitions without forward declarations
screams that you have modeled your code on some text dating from the
late 70s or early 80s, and your use of end-of-line characters to begin
lines smacks of old Borland (or worse, old Schildt) instruction
materials. To get you started, look at the following compiled but not
tested code. Whether it does what you want is unknown, but it should
point you toward writing slightly better code.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define BIGENOUGH 2048
#define C_SENTINAL 9999
struct customer_record
{
int customer_no;
int no_of_weeks;
char tv_type;
};
void weeks_rental(st ruct customer_record *cust, double *due,
double *re_per_week);
void print_bill(stru ct customer_record *cust, double rent, double due);
void summary(void);
double round_to_cent(d ouble x)
{
double b, f;
b = modf(100 * x, &f);
if (f >= .5)
b++;
return b / 100;
}
int main(void)
{
struct customer_record customer;
FILE *fp_rent, *fp_summ;
double rent_per_week, rentdue, rent_out;
char buf[BIGENOUGH], *nl;
/* Open files. Old master(read), temporary file(write) */
if ((fp_rent = fopen("setup.tx t", "r")) == NULL) {
fprintf(stderr, "Can not open file 'setup.txt' for reading \n"
"Program is terminated.");
exit(EXIT_FAILU RE);
}
if ((fp_summ = fopen("summ.txt ", "w")) == NULL) {
fprintf(stderr, "Can not open file 'summ' for writing \n"
"Program is terminated.");
exit(EXIT_FAILU RE);
}
/* get data */
while (fgets(buf, sizeof buf, fp_rent)) {
if ((nl = strchr(buf, '\n')))
*nl = 0;
if (4 != sscanf(buf, "%4d%2d%c", &customer.custo mer_no,
&customer.no_of _weeks, &customer.tv_ty pe)) {
fprintf(stderr, "The input line\n \"%s\"\nis ill-formed.\n"
"Program is terminated.", buf);
exit(EXIT_FAILU RE);
}
/* and process the bill */
if (customer.custo mer_no == C_SENTINAL)
break;
weeks_rental(&c ustomer, &rentdue, &rent_per_week) ;
rent_out = round_to_cent(r entdue);
fprintf(fp_summ , "%4d %2d %c %6.2f\n", customer.custom er_no,
customer.no_of_ weeks, customer.tv_typ e, rent_out);
if (rent_per_week)
print_bill(&cus tomer, rent_per_week, rentdue);
}
fclose(fp_rent) ;
fclose(fp_summ) ;
return 0;
}
void weeks_rental(st ruct customer_record *cust, double *due,
double *re_per_week)
{
/* rent per week */
switch (cust->tv_type) {
case 'c':
*due = cust->no_of_weeks * 3.60;
*re_per_week = 3.60;
case 'b':
*due = cust->no_of_weeks * 1.75;
*re_per_week = 1.75;
case 'v':
*due = cust->no_of_weeks * 1.50;
*re_per_week = 1.50;
default:
fprintf(stderr,
"Program does not handle this type of rental\n");
}
}
void print_bill(stru ct customer_record *cust, double rent, double due)
{
printf("TV Rental bill\n"
" =============== =========\n\n"
" Customer number is %d\n"
" Number of weeks rent due is %d\n"
" Rent per week is %.2f\n\n" " Rental due is %.2f\n\n",
cust->customer_no, cust->no_of_weeks, rent, due);
} eh**********@gm ail.com wrote: I know one of the pointer benefit is that we can return more than one
value from a function . The down program has an error that I can not
discover .
The most obvious error is in lines like fprintf(fp_summ ,"%4d %2d %c %6d\n",customer ,rent_out);
where customer is a struct. This obviously cannot work.
Your use of K&R-style function definitions without forward declarations
screams that you have modeled your code on some text dating from the
late 70s or early 80s, and your use of end-of-line characters to begin
lines smacks of old Borland (or worse, old Schildt) instruction
materials. To get you started, look at the following compiled but not
tested code. Whether it does what you want is unknown, but it should
point you toward writing slightly better code.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define BIGENOUGH 2048
#define C_SENTINAL 9999
struct customer_record
{
int customer_no;
int no_of_weeks;
char tv_type;
};
void weeks_rental(st ruct customer_record *cust, double *due,
double *re_per_week);
void print_bill(stru ct customer_record *cust, double rent, double due);
void summary(void);
double round_to_cent(d ouble x)
{
double b, f;
b = modf(100 * x, &f);
if (f >= .5)
b++;
return b / 100;
}
int main(void)
{
struct customer_record customer;
FILE *fp_rent, *fp_summ;
double rent_per_week, rentdue, rent_out;
char buf[BIGENOUGH], *nl;
/* Open files. Old master(read), temporary file(write) */
if ((fp_rent = fopen("setup.tx t", "r")) == NULL) {
fprintf(stderr, "Can not open file 'setup.txt' for reading \n"
"Program is terminated.");
exit(EXIT_FAILU RE);
}
if ((fp_summ = fopen("summ.txt ", "w")) == NULL) {
fprintf(stderr, "Can not open file 'summ' for writing \n"
"Program is terminated.");
exit(EXIT_FAILU RE);
}
/* get data */
while (fgets(buf, sizeof buf, fp_rent)) {
if ((nl = strchr(buf, '\n')))
*nl = 0;
if (4 != sscanf(buf, "%4d%2d%c", &customer.custo mer_no,
&customer.no_of _weeks, &customer.tv_ty pe)) {
fprintf(stderr, "The input line\n \"%s\"\nis ill-formed.\n"
"Program is terminated.", buf);
exit(EXIT_FAILU RE);
}
/* and process the bill */
if (customer.custo mer_no == C_SENTINAL)
break;
weeks_rental(&c ustomer, &rentdue, &rent_per_week) ;
rent_out = round_to_cent(r entdue);
fprintf(fp_summ , "%4d %2d %c %6.2f\n", customer.custom er_no,
customer.no_of_ weeks, customer.tv_typ e, rent_out);
if (rent_per_week)
print_bill(&cus tomer, rent_per_week, rentdue);
}
fclose(fp_rent) ;
fclose(fp_summ) ;
return 0;
}
void weeks_rental(st ruct customer_record *cust, double *due,
double *re_per_week)
{
/* rent per week */
switch (cust->tv_type) {
case 'c':
*due = cust->no_of_weeks * 3.60;
*re_per_week = 3.60;
break;
case 'b':
*due = cust->no_of_weeks * 1.75;
*re_per_week = 1.75;
break;
case 'v':
*due = cust->no_of_weeks * 1.50;
*re_per_week = 1.50;
break;
default:
fprintf(stderr,
"Program does not handle this type of rental\n");
}
}
void print_bill(stru ct customer_record *cust, double rent, double due)
{
printf("TV Rental bill\n"
" =============== =========\n\n"
" Customer number is %d\n"
" Number of weeks rent due is %d\n"
" Rent per week is %.2f\n\n" " Rental due is %.2f\n\n",
cust->customer_no, cust->no_of_weeks, rent, due);
} This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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