text: #include <dirent.h>
  int closedir(DIR *dirp);
  DIR *opendir(const char *dirname);
  struct dirent *readdir(DIR *dirp);
  void rewinddir(DIR *dirp);
  void seekdir(DIR *dirp, long int loc);
  long int telldir(DIR *dirp);
  readdir returns a pointer to the next active directory entry. No inactive entries are returned. It returns NULL upon reaching the end of the directory or upon detecting an invalid location in the directory.
  telldir returns the current location associated with the named directory stream.
  seekdir sets the position of the next readdir operation on the directory stream. The new position, loc, is the position associated with the directory stream when the telldir operation was performed. Values returned by telldir are good only if the directory has not changed due to compaction or expansion. This is not a problem with System V, but it may be with some file system types.
  rewinddir resets the position of the named directory stream to the beginning of the directory.
  closedir closes the named directory stream and frees the DIR structure.
  The following errors can occur as a result of these operations.
  opendir:
  readdir:
  closedir:
  dirp = opendir( "." ); while ( (dp = readdir( dirp )) != NULL ) if ( strcmp( dp->d_name, name ) == 0 ) { closedir( dirp ); return FOUND; } closedir( dirp ); return NOT_FOUND;
  X/Open Portability Guide, Issue 3, 1989
  ;
  IEEE POSIX Std 1003.1-1990 System Application Program Interface (API) [C Language] (ISO/IEC 9945-1) ;
  and NIST FIPS 151-1 .
  seekdir and telldir are conformant with:
  X/Open Portability Guide, Issue 3, 1989 .