[ale] Stupid C Question

[Tom Wiencko]

What a fun little problem.  Least effort is to find the fields in
the buffer, and build pointers to them.  This is C after all, and C
is a pointer hacker's heaven.  Here's one way to do it:

#include <stdio.h> 

#define INFILE "test.cfg"
#define MAXBUF 1024          	/* max buffer length */
#define MAXFIELDS 1024		/* memory is cheap */
#define DELIMETER ':'

parse (char delim, char *in, char ** ptrs)
{
	register char *inptr=in;
	register delimfound=1;  /* beginning of line is always a delimeter */
	register count=0;

	while (*in != '\0') {
		if (*in == delim) {
			*in='\0';
			delimfound=1;
		}  else
		if (delimfound) { 
/* current char is good, last was delimeter */
			*ptrs++ = in;
			delimfound=0;	
			count++;
		}
		in++;
	}	
	return (count);
}

int main(char *ac, char ** av) {

	char buffer[MAXBUF];
	char *pointers[MAXFIELDS];
	FILE * f;
	int i, count;

	if (NULL != ( f=fopen(INFILE, "r") ) ) {
		while (EOF != (fscanf(f, "%s", buffer) ) ) {
			count=parse(DELIMETER, buffer, pointers); 
/* array "pointers" is now an array of pointers to the fields */

/* let's print 'em out and make sure it works */
			printf ("%d fields found\n",count);
			for (i=0; i<count; i++) {
				printf("field is |%s|\n", pointers[i]);			
			}	
			printf ("new line\n");

		}
	} else {
		printf ("cannot open file!\n");
	}
} 

Of course, since this is C, there are billions of other ways to do it
as well.

Tom


Chris Fowler wrote:
> 
> I have a file that looks like this
> 
> DATA:DATA:DATA
> DATA:DATA:DATA
> 
> Each line is a new record and the DATA of each one can be of variable
> length.  I have tried to read the whole file in buffer and use sscanf
> to parse but that seems to yield no results.  I want to place each
> piece of DATA into character arrays.  The number of records in the
> file could be variable as well.  Any help on this would be greatly
> appreciate.  If you could point me to good documentation on reading,
> writing, parsing, and changing of disks files using C, I would
> appreciate that to.  I have many books on C but non really explain how
> to work with files.  Most of my files are config files that I am
> trying to create an interface to change them.
> 
> Thanks,
> Chris

-- 
------------------------------------------------------------------------
Tom Wiencko                                              tew at wiencko.com
President - Wiencko & Associates, Inc.                    (404) 255-2330
Telecom Consulting & Project Development -- Wireline, Wireless, Internet
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