Redirecting input from file

**Eric Sosman** · Jun 28 '07, 04:25 PM

Re: Redirecting input from file

dmoran21@cox.ne t wrote On 06/28/07 11:30,:

Hi All, I am working on a program to take input from a txt file, do
some calculations, and then output the results to another txt file.
The program that I've written compiles fine for me, however, when I
run it, it stalls and does nothing. I'm wondering if there's something
obvious that I'm missing. My code is below and any help would be
appreciated.

There are several problems, and perhaps more than I've
spotted in a quick scan. I've noted a few of them below:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
>
int main(int argc, char *argv[])
{
/* Variable Declarations */
const int arraylength = 5000;
const int errorcode = -1;
float sum = 0;
int count = 0;
int condition = 1;
float* precipvals = (float*)NULL;
float* precip3hrs = (float*)NULL;
long* date = (long*)NULL;

The casts are harmless, but unnecessary.

FILE *fpin;
FILE *fpout;
>
fpin = fopen(argv[1],"r+");

Why "r+" instead of just "r", since all you do is
read from the file? Also, you should check the values
returned by both fopen() calls to see if fopen() failed.

fpout = fopen(argv[2],"w");
>
/* Array Allocation */
precipvals = (float*)malloc( sizeof(int) * arraylength);
precip3hrs = (float*)malloc( sizeof(int) * arraylength);
date = (long*)malloc(s izeof(int) * arraylength);

More unnecessary but harmless casts. A worse problem
is that you don't check any of the malloc() calls for
failure. Worst of all is that you request space for
so-and-so many ints, but the things you're actually going
to store are floats and longs!

>
/* Calculation Section */
while(condition != EOF) {
condition = fscanf(fpin,"%l ,%f", &date[count], &precipvals[count]);
if(feof(fpin)) {
fclose(fpin);
return -3;

That's a pretty weird exit value. It may mean something
on your system, but if it does the meaning is far from
universal. The only "portable" exit values are EXIT_SUCCESS
and zero (both meaning "success") and EXIT_FAILURE.

}
if(count == 1) {
precip3hrs[count] = precipvals[count];
}
if(count == 2) {
precip3hrs[count] = precipvals[count] + precip3hrs[count-1];
}
if(count 2) {
precip3hrs[count] = precipvals[count] + precipvals[count-1] +
precipvals[count-2];
}

Since count was initialized to zero and there's nothing
to change its value, this loop just reads and reads and reads
and does nothing. Also, if fscanf() ever runs across something
it can't interpret, it'll return the number of items it was
able to convert (zero or one) and leave the unintelligible
junk still un-read. On the next call it will still be unable
to convert the junk, so it will return zero and leave the junk
un-read. On the next call it will still be unable ...

The upshot: If there's anything wrong anywhere in the input,
this loop will never finish. If the input data is perfectly
formatted, this loop will read all the way through the file
and do essentially nothing. When (if) it reaches the end of
the input, feof(pin) will return true and the program will
exit.

}

As far as I can see, there's no way for the program to
arrive at this point. But if it did ...

/* Output section */
for(count = 1; count <= arraylength; count++) {

On the final trip through this loop, count will equal
arraylength and you'll try to use the [arraylength] elements
of your arrays. Since you've only allocated space for [0]
through [arraylength-1] (if that; see above), that'll be
a problem.

Also, the only array elements that have ever had anything
stored in them are the [0] elements of date and precipvals.
Nothing has ever been stored in the higher-numbered elements
of those two arrays, nor in any element of precip3hrs.

Finally, assuming you fix up the input loop so it actually
does something useful, what happens if the input has 3000
lines instead of 5000? (Or worse: What if it has 6000?)
Do you really want to loop through the entire array, or just
through the array elements that correspond to inputs?

if(count == 1) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}
if(count == 2) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}
if(count 2) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}
}
>
/* Write to file */
for(count = 1; count <= arraylength; count++) {

Same remarks as for the previous loop.

if(count == 1) {
fprintf(fpout, "One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}
if(count == 2) {
fprintf(fpout," One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}
if(count 2) {
fprintf(fpout," One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}
}
fclose(fpin);
fclose(fpout);

Believe it or not, fclose() can fail. Failure of the
first one probably doesn't hurt your program any, but if
the second fails it very likely means that some part of the
output file didn't get written. Do you want to proclaim
"Success!" if that happens?

/* Deallocation */
free(date);
date = (long*)NULL;
free(precipvals );
precipvals = (float*)NULL;
free(precip3hrs );
precip3hrs = (float*)NULL;

More useless casts. (Useless assignments, too, IMHO.)

return 0;
}

--
Eric.Sosman@sun .com

AG · Jun 28 '07, 04:25 PM

Re: Redirecting input from file

Hi Dave, some hints below :

Dave
>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
>
int main(int argc, char *argv[])
{
/* Variable Declarations */
const int arraylength = 5000;
const int errorcode = -1;
float sum = 0;
int count = 0;
int condition = 1;
float* precipvals = (float*)NULL;
float* precip3hrs = (float*)NULL;
long* date = (long*)NULL;
FILE *fpin;
FILE *fpout;
>
fpin = fopen(argv[1],"r+");
fpout = fopen(argv[2],"w");
>
/* Array Allocation */
precipvals = (float*)malloc( sizeof(int) * arraylength);
precip3hrs = (float*)malloc( sizeof(int) * arraylength);
date = (long*)malloc(s izeof(int) * arraylength);

check if malloc returned a NULL pointer.

>
/* Calculation Section */
while(condition != EOF) {
condition = fscanf(fpin,"%l ,%f", &date[count], &precipvals[count]);

Could you show us the file ? It seems that count is never incremented
and always equal 1 ?

if(feof(fpin)) {
fclose(fpin);
return -3;
}
if(count == 1) {
precip3hrs[count] = precipvals[count];
}
if(count == 2) {
precip3hrs[count] = precipvals[count] + precip3hrs[count-1];
}
if(count 2) {
precip3hrs[count] = precipvals[count] + precipvals[count-1] +
precipvals[count-2];
}
}
>
/* Output section */
for(count = 1; count <= arraylength; count++) {
if(count == 1) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}

If count == arraylength, then you do an overflow. You can write inside
precipvals using index [0 to arrayval-1].

if(count == 2) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}
if(count 2) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}
}
>
/* Write to file */
for(count = 1; count <= arraylength; count++) {
if(count == 1) {
fprintf(fpout, "One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}

same comment about overflows.

if(count == 2) {
fprintf(fpout," One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}
if(count 2) {
fprintf(fpout," One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}
}
fclose(fpin);
fclose(fpout);
>
/* Deallocation */
free(date);
date = (long*)NULL;
free(precipvals );
precipvals = (float*)NULL;
free(precip3hrs );
precip3hrs = (float*)NULL;
return 0;
}
>

**Richard Heathfield** · Jun 28 '07, 04:35 PM

Re: Redirecting input from file

dmoran21@cox.ne t said:

Hi All, I am working on a program to take input from a txt file, do
some calculations, and then output the results to another txt file.
The program that I've written compiles fine for me, however, when I
run it, it stalls and does nothing. I'm wondering if there's something
obvious that I'm missing. My code is below and any help would be
appreciated.

I've made some obvious corrections - removed all the casts, added a bit
of error checking, fixed a couple of broken loop bounds...

But I can't test because I don't have the data that you have.

So here's the semi-corrected code. I'm not saying it fixes your problem,
but you might find that it at least prints out a complaint at runtime,
in which case it would be useful to know which complaint it prints.

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(int argc,
char *argv[])
{
/* Variable Declarations */
const int arraylength = 5000;
int count = 0;
int condition = 1;
float *precipvals = NULL;
float *precip3hrs = NULL;
long *date = NULL;
FILE *fpin;
FILE *fpout;

if(argc 2)
{
fpin = fopen(argv[1], "r+");
if(fpin != NULL)
{
fpout = fopen(argv[2], "w");
if(fpout != NULL)
{
/* Array Allocation */
precipvals = malloc(arraylen gth *
sizeof *precipvals);
if(precipvals != NULL)
{
precip3hrs = malloc(arraylen gth *
sizeof *precip3hrs);
if(precip3hrs != NULL)
{
date = malloc(arraylen gth *
sizeof *date);
if(date != NULL)
{
/* Calculation Section */
while(condition != EOF)
{
condition =
fscanf(fpin,
"%ld,%f",
&date[count],
&precipvals[count]);
if(feof(fpin))
{
fclose(fpin);
fprintf(stderr,
"Last datum read, program closing now.\n");
return EXIT_FAILURE;
}
if(count == 1)
{
precip3hrs[count] = precipvals[count];
}
else if(count == 2)
{
precip3hrs[count] =
precipvals[count] + precip3hrs[count - 1];
}
else if(count 2)
{
precip3hrs[count] =
precipvals[count] + precipvals[count - 1] +
precipvals[count - 2];
}
}

/* Output section */
for(count = 1; count < arraylength; count++)
{
if(count == 1)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
else if(count == 2)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
else if(count 2)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
}

/* Write to file */
for(count = 1; count < arraylength; count++)
{
if(count == 1)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
if(count == 2)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
if(count 2)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
}
free(date);
}
else
{
fprintf(stderr, "Allocation failure: date\n");
}
free(precip3hrs );
}
else
{
fprintf(stderr, "Allocation failure: precip3hrs\n");
}
free(precipvals );
}
else
{
fprintf(stderr, "Allocation failure: precipvals\n");
}
fclose(fpout);
}
else
{
fprintf(stderr, "Can't open %s for writing.\n", argv[2]);
}
fclose(fpin);
}
else
{
fprintf(stderr, "Can't open %s for reading\n", argv[1]);
}
}
else
{
fprintf(stderr, "Need more args.\n");
}

return 0;
}

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

**dmoran21@cox.net** · Jun 28 '07, 05:05 PM

Re: Redirecting input from file

On Jun 28, 11:29 am, Richard Heathfield <r...@see.sig.i nvalidwrote:

dmora...@cox.ne t said:
>

Hi All, I am working on a program to take input from a txt file, do
some calculations, and then output the results to another txt file.
The program that I've written compiles fine for me, however, when I
run it, it stalls and does nothing. I'm wondering if there's something
obvious that I'm missing. My code is below and any help would be
appreciated.

>
I've made some obvious corrections - removed all the casts, added a bit
of error checking, fixed a couple of broken loop bounds...
>
But I can't test because I don't have the data that you have.
>
So here's the semi-corrected code. I'm not saying it fixes your problem,
but you might find that it at least prints out a complaint at runtime,
in which case it would be useful to know which complaint it prints.
>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
>
int main(int argc,
char *argv[])
{
/* Variable Declarations */
const int arraylength = 5000;
int count = 0;
int condition = 1;
float *precipvals = NULL;
float *precip3hrs = NULL;
long *date = NULL;
FILE *fpin;
FILE *fpout;
>
if(argc 2)
{
fpin = fopen(argv[1], "r+");
if(fpin != NULL)
{
fpout = fopen(argv[2], "w");
if(fpout != NULL)
{
/* Array Allocation */
precipvals = malloc(arraylen gth *
sizeof *precipvals);
if(precipvals != NULL)
{
precip3hrs = malloc(arraylen gth *
sizeof *precip3hrs);
if(precip3hrs != NULL)
{
date = malloc(arraylen gth *
sizeof *date);
if(date != NULL)
{
/* Calculation Section */
while(condition != EOF)
{
condition =
fscanf(fpin,
"%ld,%f",
&date[count],
&precipvals[count]);
if(feof(fpin))
{
fclose(fpin);
fprintf(stderr,
"Last datum read, program closing now.\n");
return EXIT_FAILURE;
}
if(count == 1)
{
precip3hrs[count] = precipvals[count];
}
else if(count == 2)
{
precip3hrs[count] =
precipvals[count] + precip3hrs[count - 1];
}
else if(count 2)
{
precip3hrs[count] =
precipvals[count] + precipvals[count - 1] +
precipvals[count - 2];
}
}
>
/* Output section */
for(count = 1; count < arraylength; count++)
{
if(count == 1)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
else if(count == 2)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
else if(count 2)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
}
>
/* Write to file */
for(count = 1; count < arraylength; count++)
{
if(count == 1)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
if(count == 2)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
if(count 2)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
}
free(date);
}
else
{
fprintf(stderr, "Allocation failure: date\n");
}
free(precip3hrs );
}
else
{
fprintf(stderr, "Allocation failure: precip3hrs\n");
}
free(precipvals );
}
else
{
fprintf(stderr, "Allocation failure: precipvals\n");
}
fclose(fpout);
}
else
{
fprintf(stderr, "Can't open %s for writing.\n", argv[2]);
}
fclose(fpin);
}
else
{
fprintf(stderr, "Can't open %s for reading\n", argv[1]);
}
}
else
{
fprintf(stderr, "Need more args.\n");
}
>
return 0;
>
}
>
--
Richard Heathfield <http://www.cpax.org.uk >
Email: -www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

Thanks for the help. I'll give it a go.

Dave

**Richard Heathfield** · Jun 28 '07, 05:05 PM

Re: Redirecting input from file

dmoran21@cox.ne t said:

Thanks for the help. I'll give it a go.

When you do, take note of the comments others have made in this thread,
especially regarding the loop counter! You'll need to fix that before
you can find the other bugs.

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

**dmoran21@cox.net** · Jun 28 '07, 08:55 PM

Re: Redirecting input from file

On Jun 28, 11:21 am, "AG" <a...@tb.frwrot e:

Hi Dave, some hints below :
>

Dave

>

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

>

int main(int argc, char *argv[])
{
/* Variable Declarations */
const int arraylength = 5000;
const int errorcode = -1;
float sum = 0;
int count = 0;
int condition = 1;
float* precipvals = (float*)NULL;
float* precip3hrs = (float*)NULL;
long* date = (long*)NULL;
FILE *fpin;
FILE *fpout;

>

fpin = fopen(argv[1],"r+");
fpout = fopen(argv[2],"w");

>

/* Array Allocation */
precipvals = (float*)malloc( sizeof(int) * arraylength);
precip3hrs = (float*)malloc( sizeof(int) * arraylength);
date = (long*)malloc(s izeof(int) * arraylength);

>
check if malloc returned a NULL pointer.
>
>
>

/* Calculation Section */
while(condition != EOF) {
condition = fscanf(fpin,"%l ,%f", &date[count], &precipvals[count]);

>
Could you show us the file ? It seems that count is never incremented
and always equal 1 ?

I fixed the increment. I discovered this when my boss and I were
looking at it today in my office.

>
>
>

if(feof(fpin)) {
fclose(fpin);
return -3;
}
if(count == 1) {
precip3hrs[count] = precipvals[count];
}
if(count == 2) {
precip3hrs[count] = precipvals[count] + precip3hrs[count-1];
}
if(count 2) {
precip3hrs[count] = precipvals[count] + precipvals[count-1] +
precipvals[count-2];
}
}

>

/* Output section */
for(count = 1; count <= arraylength; count++) {
if(count == 1) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}

>
If count == arraylength, then you do an overflow. You can write inside
precipvals using index [0 to arrayval-1].
>
>
>

if(count == 2) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}
if(count 2) {
printf("One hour precipitation: %2.2f Three hour precipitation %2.2f
\n",precipval s[count],precip3hrs[count]);
}
}

>

/* Write to file */
for(count = 1; count <= arraylength; count++) {
if(count == 1) {
fprintf(fpout, "One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}

>
same comment about overflows.

That's what I thought. My co worker said I needed the <=, I originally
just had <

>

if(count == 2) {
fprintf(fpout," One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}
if(count 2) {
fprintf(fpout," One hour precipitation: %2.2f Three hour
precipitation %2.2f\n",precip vals[count],precip3hrs[count]);
}
}
fclose(fpin);
fclose(fpout);

>

/* Deallocation */
free(date);
date = (long*)NULL;
free(precipvals );
precipvals = (float*)NULL;
free(precip3hrs );
precip3hrs = (float*)NULL;
return 0;
}

Thanks for all the tips. I'm at home now, but will check it out when I
get to the office in the morning.

Dave

**Roland Pibinger** · Jun 28 '07, 09:45 PM

Re: Redirecting input from file

On Thu, 28 Jun 2007 16:29:55 +0000, Richard Heathfield wrote:

if(argc 2) ...
if(fpin != NULL) ...
if(fpout != NULL) ...
if(precipvals != NULL) ...
if(precip3hrs != NULL) ...
if(date != NULL) ...
while(condition != EOF) ...
if(feof(fpin)) ...
if(count == 1) ...
else if(count == 2) ...
else if(count 2) ...
for(count = 1; count < arraylength; count++) ...
if(count == 1) ...
else if(count == 2) ...
else if(count 2) ...
for(count = 1; count < arraylength; count++) ...
if(count == 1) ...
if(count == 2) ...
if(count 2) ...
else ...
else ...
else ...
else ...
else ...
else ...

Are you serious? 160 lines of nested if/else and loops in one
function?

--
Roland Pibinger
"The best software is simple, elegant, and full of drama" - Grady Booch

**Richard Heathfield** · Jun 28 '07, 10:55 PM

Re: Redirecting input from file

Roland Pibinger said:

<snip>

Are you serious? 160 lines of nested if/else and loops in one
function?

Minimal edits consistent with adding the error checking that the OP
lacked. I wasn't about to refactor it for him as well - he can do that
himself, surely?

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

**Barry Schwarz** · Jun 29 '07, 01:25 AM

Re: Redirecting input from file

On Thu, 28 Jun 2007 09:56:02 -0700, "dmoran21@cox.n et"
<dmoran21@cox.n etwrote:

snip

>Thanks for the help. I'll give it a go.
>

Please don't quote 200 lines just to say thanks.

Remove del for email

**Chris Dollin** · Jun 29 '07, 08:25 AM

Re: Redirecting input from file

dmoran21@cox.ne t wrote:

Hi All, I am working on a program to take input from a txt file, do
some calculations, and then output the results to another txt file.
The program that I've written compiles fine for me, however, when I
run it, it stalls and does nothing. I'm wondering if there's something
obvious that I'm missing. My code is below and any help would be
appreciated.

I'm going to make style points fir which other people have other
aesthetics.

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
>
int main(int argc, char *argv[])
{
/* Variable Declarations */
const int arraylength = 5000;
const int errorcode = -1;
float sum = 0;
int count = 0;
int condition = 1;
float* precipvals = (float*)NULL;
float* precip3hrs = (float*)NULL;

(a) You don't need to cast the NULL, so you shouldn't.

(b) You're going to assign to these two variables unconditionally
below, so there's no point in assigning null to them at all,
/especially/ since you're happy with initialised declarations.

Just do

float* precipvals = malloc( sizeof(int) * arraylength );
float* precip3hrs = malloc( sizeof(int) * arraylength );

(c) You don't need the casts on the `malloc` result, so (as you
see in (b) you can [and I would say /should/] remove them.

(d) You should check that `malloc` has succeeded.

long* date = (long*)NULL;
FILE *fpin;
FILE *fpout;
>
fpin = fopen(argv[1],"r+");
fpout = fopen(argv[2],"w");

(d) You might as well combine the declaration with the assignment.

(e) You should check that the `fopen`s succeed.

(f) In fact, since the files failing to fopen is death to your code
anyway, I'd suggest doing the fopens /first/, and structuring
your code like:

FILE *fpin = fopen(argv[1],"r+");
FILE *fpout = fopen(argv[2],"w");
if (fpin && fpout)
callFunctionTha tDoesTheStuffWi thTheFiles( fpin, fpout );
else
{
... code that handles files failing to fopen
}
if (fpin) close( fpin );
if (fpout) close( fpout );

That concentrates all the file opening-and-closing-and-complaining
in a short span of text.

/* Calculation Section */

Make the (snipped) code here a function with a nice name.

/* Output section */

Ditto.

/* Write to file */

Ditto.

/* Deallocation */
free(date);
date = (long*)NULL;
free(precipvals );
precipvals = (float*)NULL;
free(precip3hrs );
precip3hrs = (float*)NULL;

The assignments of null are unnecessary and distracting.

return 0;
}

--
Hewlett-Packard Limited Cain Road, Bracknell, registered no:
registered office: Berks RG12 1HN 690597 England

**Army1987** · Jun 29 '07, 02:15 PM

Re: Redirecting input from file

"Richard Heathfield" <rjh@see.sig.in validha scritto nel messaggio news:goydnWQaEp DlfB7bRVnygAA@b t.com...

dmoran21@cox.ne t said:
>

>Hi All, I am working on a program to take input from a txt file, do
>some calculations, and then output the results to another txt file.
>The program that I've written compiles fine for me, however, when I
>run it, it stalls and does nothing. I'm wondering if there's something
>obvious that I'm missing. My code is below and any help would be
>appreciated.

>
I've made some obvious corrections - removed all the casts, added a bit
of error checking, fixed a couple of broken loop bounds...
>
But I can't test because I don't have the data that you have.
>
So here's the semi-corrected code. I'm not saying it fixes your problem,
but you might find that it at least prints out a complaint at runtime,
in which case it would be useful to know which complaint it prints.
>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
>
int main(int argc,
char *argv[])
{
/* Variable Declarations */
const int arraylength = 5000;
int count = 0;
int condition = 1;
float *precipvals = NULL;
float *precip3hrs = NULL;
long *date = NULL;
FILE *fpin;
FILE *fpout;
>
if(argc 2)
{
fpin = fopen(argv[1], "r+");
if(fpin != NULL)
{
fpout = fopen(argv[2], "w");
if(fpout != NULL)
{
/* Array Allocation */
precipvals = malloc(arraylen gth *
sizeof *precipvals);
if(precipvals != NULL)
{
precip3hrs = malloc(arraylen gth *
sizeof *precip3hrs);
if(precip3hrs != NULL)
{
date = malloc(arraylen gth *
sizeof *date);
if(date != NULL)
{
/* Calculation Section */
while(condition != EOF)
{
condition =
fscanf(fpin,
"%ld,%f",
&date[count],
&precipvals[count]);
if(feof(fpin))
{
fclose(fpin);
fprintf(stderr,
"Last datum read, program closing now.\n");
return EXIT_FAILURE;
}
if(count == 1)
{
precip3hrs[count] = precipvals[count];
}
else if(count == 2)
{
precip3hrs[count] =
precipvals[count] + precip3hrs[count - 1];
}
else if(count 2)
{
precip3hrs[count] =
precipvals[count] + precipvals[count - 1] +
precipvals[count - 2];
}
}
>
/* Output section */
for(count = 1; count < arraylength; count++)
{
if(count == 1)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
else if(count == 2)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
else if(count 2)
{
printf
("One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
}
>
/* Write to file */
for(count = 1; count < arraylength; count++)
{
if(count == 1)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
if(count == 2)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
if(count 2)
{
fprintf(fpout,
"One hour precipitation: %2.2f"
" Three hour precipitation %2.2f\n",
precipvals[count],
precip3hrs[count]);
}
}
free(date);
}
else
{
fprintf(stderr, "Allocation failure: date\n");
}
free(precip3hrs );
}
else
{
fprintf(stderr, "Allocation failure: precip3hrs\n");
}
free(precipvals );
}
else
{
fprintf(stderr, "Allocation failure: precipvals\n");
}
fclose(fpout);
}
else
{
fprintf(stderr, "Can't open %s for writing.\n", argv[2]);
}
fclose(fpin);
}
else
{
fprintf(stderr, "Can't open %s for reading\n", argv[1]);
}
}
else
{
fprintf(stderr, "Need more args.\n");
}
>
return 0;
}

Apparently this will *always* return 0, no matter what happens...
Why do you think that having umpteen nested if statements is any
less bad than ever calling exit(EXIT_FAILU RE)? I remember about
your double ctx2174_frob_fo o(foo *f, bar *b, baz *z, quux *q), but
this isn't much clearer...

**Eric Sosman** · Jun 29 '07, 02:25 PM

Re: Redirecting input from file

Chris Dollin wrote On 06/29/07 04:10,:

[...]
>
float* precipvals = malloc( sizeof(int) * arraylength );

^^^^^ ^^^

float* precip3hrs = malloc( sizeof(int) * arraylength );

^^^^^ ^^^

Avoiding this error is one of the chief virtues of
the c.l.c. Orthodox Allocation Idiom:

AnyType *ptr = malloc(sizeof *ptr * arraylength);

--
Eric.Sosman@sun .com

**Richard Heathfield** · Jun 30 '07, 05:55 AM

Re: Redirecting input from file

Army1987 said:

<huge snip, which was really your job, not mine>

Apparently this will *always* return 0, no matter what happens...

Yeah. I said I fixed *some* of his problems, not all of them. The code
needs refactoring[1]. I am prepared to spend a considerable amount of
my time helping people out, for free, but I get to decide where I stop.
And on this occasion I chose to stop at the point where I'd stripped
out pointless casts, added a small handful of tests, and put the
free()s and fclose()s in the right places. Oh, and I corrected a couple
of loop termination conditions.

I didn't look closer at the code than that, but then I didn't claim that
I'd fixed his problem, either.

I did suggest that this might give better diagnostic information (which
is true in the long term, but it turns out that he had loop counter
problems, among other things). In a later reply, having read the loop
counter replies of others, I pointed the OP to them.

If you want the code re-factored, *you* do it.

[1] In fact, to be brutally honest, the code wants discarding and
rewriting from scratch by someone more experienced with C.

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

**Army1987** · Jun 30 '07, 08:05 AM

Re: Redirecting input from file

"Richard Heathfield" <rjh@see.sig.in validha scritto nel messaggio news:GbqdneCFw-1ncBjbnZ2dnUVZ8 vqdnZ2d@bt.com. ..

Army1987 said:
>
<huge snip, which was really your job, not mine>
>

>Apparently this will *always* return 0, no matter what happens...

>
Yeah. I said I fixed *some* of his problems, not all of them. The code
needs refactoring[1]. I am prepared to spend a considerable amount of
my time helping people out, for free, but I get to decide where I stop.
And on this occasion I chose to stop at the point where I'd stripped
out pointless casts, added a small handful of tests, and put the
free()s and fclose()s in the right places. Oh, and I corrected a couple
of loop termination conditions.
>
I didn't look closer at the code than that, but then I didn't claim that
I'd fixed his problem, either.
>
I did suggest that this might give better diagnostic information (which
is true in the long term, but it turns out that he had loop counter
problems, among other things). In a later reply, having read the loop
counter replies of others, I pointed the OP to them.
>
If you want the code re-factored, *you* do it.

Do you mean that, when the OP wrote:
fpin = fopen(argv[1],"r+");
fpout = fopen(argv[2],"w");
you found it easier to write that code than simplily to add

fpin = fopen(argv[1], "r+");
if (fpin == NULL) {
fprintf(stderr, "Cannot open '%s': %s\n", argv[1],
strerror(errrno ));
exit(EXIT_FAILU RE);
}
fpout = fopen(argv[2],"w");

if (fpout == NULL) {
fprintf(stderr, "Cannot open or create '%s': %s\n", argv[2],
strerror(errrno ));
fclose(fpin);
exit(EXIT_FAILU RE);
}

Redirecting input from file

Redirecting input from file

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