Thread: Reading data from a file till there is a newline?

Code:

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

#define MAXSIZE 150

int main (void)
{
  /* By using variables starting with "str" the
  ** C standard doesn't guarantee your program to
  ** work at any time.
  */
  char fstr[MAXSIZE];
  FILE *infp;
  int count = 0;
  /* perror is specially designed to report errors
  ** after a library function fails. It gives more
  ** information than a homegrown error report in
  ** most cases and is easier to use. Also, 1 is
  ** a non-standard exit condition for main, the
  ** three portable values are 0, EXIT_SUCCESS, and
  ** EXIT_FAILURE. The last two are found in stdlib.h.
  */
  if((infp = fopen("input.txt", "rt"))== NULL) {
    perror("Unable to open input file");
    exit(EXIT_FAILURE);
  }
  printf("\nNow counting number of records on file");
  /* When reading lines you don't want to use scanf,
  ** that isn't what it is designed for. fgets on the
  ** other hand is very well suited to this task and
  ** results in shorter code if you've noticed.
  */
  while(fgets(fstr, sizeof fstr, infp)!= NULL)
    count++;

  printf("\n\nNumber of records on file is %d", count);
  getchar();
  fclose(infp);
  /* Personal preference: If I use EXIT_FAILURE 
  ** anywhere in my programs, I'll use the corresponding 
  ** macro EXIT_SUCCESS when I return from main. It just
  ** looks neater.
  */
  return EXIT_SUCCESS;
}

>For example, "one" is a word and "meaning of one" is a
>meaning of one. How would I divide each line into two pieces so
>I can have word and meaning separately?
The easiest way is to use a delimiting character which is not in the data itself to divide the line. This way you can use sscanf, strtok, and similar functions to break up the string:

one : meaning of one

Code:

if ( fgets ( a, sizeof a, file ) != NULL )
    sscanf ( a, "%s : %[^\n]", b, c );

It's also usually a good idea to double check that sscanf executed properly so that you can work out errors as close to the source as possible.

-Prelude

Originally posted by TravisS


strch looks at a string (aka charachter array) and tries to find a certain character in that array. In this case, the character it's looking for is a '\n'.

Yeah I know exactly how 'strchr' works. You are using it wrong. Let me explain:

Code:

int main (void)
{

  char str[150];
   /* 'str' is an array. */


  FILE  *infp;
  int count = 0;

  if((infp = fopen("myfile.dat", "rt"))== NULL) {
		printf("\nE R R O R : Unable to open input file");
		exit (1);
  }
  printf("\nNow counting number of records on file");

   /* file is open, that's fine */

   /* What are you doing here? */
  while((*str = fgetc(infp))!= EOF) {

           
			/* why do this? */
			if( strch(str, '\n') )
			  count++;
			}
  
  printf("\n\nNumber of records on file is %d", count);
  getchar();
  fclose(infp);
  return 0;
}

There is no point at all to use an array in your code. There is no point in using strchr (which it incidently called, there is no ansi function called 'strch').

All you ever do is use the first element of your array. Since that's the case, why bother using an array?

Furthermore, your example won't work because the fgetc call returns an integer, which is typecast into a 'char', so it will never end up returning EOF.

All you need, to do what you're attempting, is:

Code:

int c, count=0;
while( (c=fgetc(fp))!=EOF )
{
    if( c == '\n' ) count++;
}

That's all. Nothing else. No other function calls. No arrays. Your example wouldn't work right, assuming you had your function named correctly ('ll chalk that up as a typo).

Anyway, there's no point in using an array for the method you use, and your return value (of fgetc) would never evaulate as true in your loop.

Quzah.