在C中使用正则表达式捕获组填充结构

#include <stdio.h>
#include <pcre.h>

int main() {
    const char *pattern = "(\\d+)-(\\d+)-(\\d+)";
    const char *subject = "2022-01-01";
    int ovector[30];
    int rc;
    const char *error;
    int erroffset;
    pcre *re;

    re = pcre_compile(pattern, 0, &error, &erroffset, NULL);
    if (re == NULL) {
        printf("PCRE compilation failed at offset %d: %s\n", erroffset, error);
        return 1;
    }

    rc = pcre_exec(re, NULL, subject, strlen(subject), 0, 0, ovector, 30);
    if (rc < 0) {
        printf("PCRE matching failed: %d\n", rc);
        pcre_free(re);
        return 1;
    }

    int i;
    for (i = 0; i < rc; i++) {
        int start = ovector[2 * i];
        int end = ovector[2 * i + 1];
        int len = end - start;
        char captured[len + 1];
        strncpy(captured, subject + start, len);
        captured[len] = '\0';
        printf("Capture group %d: %s\n", i, captured);
    }

    pcre_free(re);
    return 0;
}