How to extract words from parentheses in C language? - c

Question

I am trying to extract words from a string like this:
(octopus kitten) (game cake) (soccer football)
I attempted doing this with the help of strtok (I do strcpy just for not modifying the original token/string, also used memcpy, but it does the same in my case).
Main function:
int main(int argc, char * argv[]) {
char row[] = "(octopus kitten) (game cake) (soccer football)";
char * pch;
pch = strtok(row, "(");
while (pch != NULL) {
pch[strcspn(pch, ")")] = '\0';
print_word(pch);
pch = strtok(NULL, "(");
}
return 0;
}
Function for getting and printing each word:
void get_and_print_word(char str[]) {
char r[4000];
// for not modifying the original string
strcpy(r, str);
char * c = strtok(r, " ");
for (int i = 0; i < 2; i++) {
printf("%s\n", c);
c = strtok(NULL, " ");
}
}
It works absolutely fine with a first iteration, but after pch starts to point to another adress of memory (but it should point to the adress of letter "g").
It works absolutely fine (it's just printing string within the brackets) if we remove get_and_print_word(pch):
int main(int argc, char * argv[]) {
char row[] = "(octopus kitten) (game cake) (soccer football)";
char * pch;
pch = strtok(row, "(");
while (pch != NULL) {
pch[strcspn(pch, ")")] = '\0';
printf("%s\n", pch);
pch = strtok(NULL, "(");
}
return 0;
}
But that's not what I want to do, I need to get each word, not just a string of two words and space between them.
Using pch = strtok(NULL, " )(") is also not appropriate in my case, cause I need to store each pair of words (each word, of couse, should be a separate string) in some individual
struct, so I definitely need this function.
How to solve this issue and why it works like this?

Answer 1

Why not use regular expression :
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <regex.h>
int main (int argc, char *argv[])
{
int err;
regex_t preg;
const char *str_request = argv[1];
const char *str_regex = argv[2];
err = regcomp (&preg, str_regex, REG_EXTENDED);
if (err == 0) {
int match;
size_t nmatch = 0;
regmatch_t *pmatch = NULL;
nmatch = preg.re_nsub;
pmatch = malloc (sizeof (*pmatch) * nmatch);
char *buffer;
if (pmatch) {
buffer = (char *) str_request;
match = regexec (&preg, buffer, nmatch, pmatch, 0);
while (match == 0) {
char *found = NULL;
size_t size ;
int start, end;
start = pmatch[0].rm_so;
end = pmatch[0].rm_eo;
size = end - start;
found = malloc (sizeof (*found) * (size + 1));
if (found) {
strncpy (found, &buffer[start], size);
found[size] = '\0';
printf ("found : %s\n", found);
free (found);
}
//searching next occurence
match = regexec (&preg, (buffer += end), nmatch, pmatch, 0);
}
regfree (&preg);
free (pmatch);
}
}
return 0;
}
[puppet#damageinc regex]$ ./regex "(octopus kitten) (game cake) (soccer football)" "([a-z]+)"
found : octopus
found : kitten
found : game
found : cake
found : soccer
found : football