xregcomp (regex_t *preg, const char *regex, int cflags);
int
xregexec (const regex_t *preg, const char *string,
size_t nmatch, regmatch_t pmatch[], int eflags);
xregcomp (regex_t *preg, const char *regex, int cflags);
int
xregexec (const regex_t *preg, const char *string,
size_t nmatch, regmatch_t pmatch[], int eflags);