A Simple libc regex.h Example

regex_example.c

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <regex.h>

#define MAXM 1024

int main(int argc, char **argv) {

    regex_t     re;
    regmatch_t  matches[MAXM];
    char        *input      = argv[2],
                *pattern    =  argv[1],
                *cursor     = input;

    if(regcomp(&re, pattern, REG_EXTENDED))
        return 1;

    while(!regexec(&re, cursor, MAXM, matches, 0)) {

        uint32_t last_pos = 0;
        for(uint32_t i = 0; i < MAXM; i++) {

            size_t e = matches[i].rm_eo,
                   s = matches[i].rm_so;

            if(s < last_pos) break;
            if(e == -1) break;

            char _cursor[strlen(cursor)];
            strcpy(_cursor, cursor);
            _cursor[e] = 0;

            last_pos = e;

            printf("'%s'\n", _cursor + s);
            cursor += last_pos;

        }
    }

    return 0;
}