C parser for data separated with comma - c

Question

What is the most effective way to write a parser in C for data with the following format:
atr#1,atr#2,...,atr#n
btr#1,btr#2,...,btr#n
...
Each record is in new line and attributes are separated with comma.
What function should be used? Do you have any examples?

Answer 1

Here's some example code that will read the file sparated by newlines line by line, then split the arguments and print them out (you can easily adapt it to, for example, parse it to an array of array of char *s):
#include <stdio.h>
#include <string.h>
int main()
{
FILE *f = fopen("file.txt", "r");
char ptr[1024];
char *token;
while (fgets(ptr, 1024, f) != NULL)
{
token = strtok(ptr, ",");
while(token)
{
printf("Token: %s\n", token);
token = strtok(NULL, ",");
}
}
fclose(f);
return 0;
}

Answer 2

This will work:
/* You need the following includes and defines */
#include <stdio.h>
#include <iostream.h>
#include <string.h>
#define NULL_CHAR 0x0
int parse(char* data) {
const int LINE_SIZE=255; /* Should be long enough for your unparsed data */
const int MAX_FIELDS=99; /* Maximum number of fields */
char output[MAX_FIELDS][LINE_SIZE];
int i;
int output_field_count;
int output_char_idx;
for (i = 0; i < MAX_FIELDS; i++) {
strcpy(output[i], "");
}
output_field_count = 0;
output_char_idx = 0;
for (i = 0; i < LINE_SIZE; i++) {
if ((data[i] != ',') &&
(output_field_count < MAX_FIELDS) &&
((output_char_idx+1) < LINE_SIZE)) {
output[output_field_count][output_char_idx] = data[i];
output[output_field_count][output_char_idx+1] = NULL_CHAR;
output_char_idx++;
}
else if (data[i] == ',') {
output_field_count++;
output_char_idx = 0;
}
}
output_field_count++;
output_char_idx = 0;
printf("OUTPUT FIELD COUNT IS: %d\n", output_field_count);
for (i = 0; i < output_field_count; i++) {
printf("FIELD %i IS: %s\n", i, output[i]);
}
return 0;
}
This can be called as follows:
char data[500]; /* Should be long enough for your unparsed data */
strcpy(data, "atr#1,atr#2,...,atr#n");
parse(data);
strcpy(data, "btr#1,btr#2,...,btr#n");
parse(data);

Answer 3

Pick the right tool for the job. It's about one line in Perl, Python, or best yet awk. If you have a compelling reason to use C, please explain in your post - otherwise I think the most judicious answer anyone can give you is to advise you to pick the right tool for the job instead of asking how to do something onerous in a language that's bad at it.
From the command line:
tr ',' '\n' < file.txt
Will turn the commas into new lines.