int ftw(const char *, int (*)(const char *, const struct stat *, int), int);
int nftw(const char *, int (*)(const char *, const struct stat *, int, struct FTW *), int, int);
int ftw(const char *, int (*)(const char *, const struct stat *, int), int);
int nftw(const char *, int (*)(const char *, const struct stat *, int, struct FTW *), int, int);