To open or not to open ?

Hi,

I am sorry to labour this point, but I cannot understand why I cannot get a count of lines in a text file

Code:

---

void check_activity(FILE ** p_fp)
{
int diff = 0;
int result = 0;
int countA = 0, countB = 0;
int ch;

    printf("before this month, last month, difference percentage %d %d %d %d\n", countA, countB, diff, result);

if(!(p_fp[OUT_FILE]))
  printf("OUT_FILE is not open !!");


/*
  rewind(p_fp[OUT_FILE]);
*/

  fseek(p_fp[OUT_FILE], 0, SEEK_SET);
  while((ch = fgetc(p_fp[OUT_FILE])) != EOF)
      if(ch == '\n')
        countA++;

printf("first count of OUT_FILE [%d]\n", countA);

  while((ch = fgetc(p_fp[LAST_FILE])) != EOF)
      if(ch == '\n')
        countB++;


  /* establish which is the largest file */
  if(countA > countB)
  {
      diff = countA - countB;
  }
  else
  {
      diff = countB - countA;
  }

  /* get the percentage to test */
  result = countA / 10;

  if(diff > result)
      cirp_process(p_fp);

    printf("after this month, last month, difference percentage %d %d %d %d\n", countA, countB, diff, result);
}

---

/* test run */
$ cirp_process september.SND august.SND
before this month, last month, difference percentage 0 0 0 0
first count of OUT_FILE [0]
YES
after this month, last month, difference percentage 0 10 10 0
$

I have swapped the order of the files as arguments, I have swapped the order of calling the parameter definitions, I have swapped the cut-n-paste while routines round the other way, I have tried rewind and fseek and I have tested to see that the file really is open.

I have also made a small function with one routine and sent the two files to it just to see, and still get the same result.

Code:

---

int get_count(FILE ** fp, int text_file)
{
int ch, count = 0;

  while((ch = fgetc(fp[text_file])) != EOF)
      if(ch == '\n')
        count++;

  return count;
}

---

/* test run */
$ cirp_process september.SND august.SND
before this month, last month, difference percentage 0 0 0 0
count of OUT_FILE [0]
count of LAST_FILE [10]
after this month, last month, difference percentage 0 10 0 0
$

However, what I do not know is this...

If I start a process and open some files, say two files, one already exists and the other doesn't, and I read the one that does, and write to the one that doesn't, do I have to close that new file and then re-open it before I can work on it ?

If that is the case, it is going to make the program a bit messy, as at present all files are opened at the start and closed at the end, and I would have to do a separate process just for this file.


tia,

That depends on the os your programming in.
Windows uses "\r\n"
Unix uses "\r"
Mac uses "\n"

Therefore if your testing for the wrong control sequence in the wrong invironment you will never know which file is bigger.

Quote:

---

Originally posted by velius
That depends on the os your programming in.
Windows uses "\r\n"
Unix uses "\r"
Mac uses "\n"

Therefore if your testing for the wrong control sequence in the wrong invironment you will never know which file is bigger.

---

If you open the file in text mode ("r"), the application will only ever see \n regardless of the OS (providing the file being read was created on the same OS as it's being read on).

As this program is a line counter, this situation is fine, if it were a byte counter, there'd be a problem.

>>do I have to close that new file and then re-open it before I can work on it ?<<
No, just make sure you open it as read/write, do fflush()'ing after writing/before reading, and don't forget to rewind() where appropriate.

my book says unix used \n for end-of-line. Not \r.

Quote:

---

Originally posted by chrismiceli
my book says unix used \n for end-of-line. Not \r.

---

Correct, Unix uses LF only (\n).
MAC, I believe, uses CR only (\r)
Windows uses CRLF

Excuse me for being human. If I'm wrong, I'm wrong. It happens.

and I need to make an even bigger apology :(

first, thanks to everyone who has posted and helped me.

The reason I am not counting any records in this particular file, is because of the way I am opening it

Code:

---

  /* Output file */
  strcpy(out_file, inp_file);
  strcpy(out_file + (strchr(out_file, '.') - out_file), OUT_SUFFIX);
  if(!(fp[OUT_FILE] = fopen(out_file, "w")))
      error_func("In file_open().", "Error : fopen(OUTPUT_FILE)", SYS | FATAL);

---

as you can see, I am opening it in write mode - ooops

>If I'm wrong, I'm wrong.
If you're wrong, you'll be corrected. Don't take it personally bud, the best way to learn new things is to make mistakes. :)