— scan a directory
scandir(const char *dirname,
struct dirent ***namelist, int
(*select)(const struct dirent *), int (*compar)(const
struct dirent **, const struct dirent **));
struct dirent **d1, const
struct dirent **d2);
function reads the directory dirname and builds an
array of pointers to directory entries using
It returns the number of entries in the array. A pointer to the array of
directory entries is stored in the location referenced by
The select parameter is a
pointer to a user-supplied subroutine which is called by
to select which entries are to be included in the array. The select routine
is passed a pointer to a directory entry and should return a non-zero value
if the directory entry is to be included in the array. If
NULL, then all
directory entries will be included.
The compar parameter is a pointer to a
user-supplied subroutine which is passed to
sort the completed array. If this pointer is
the array is not sorted.
function is a routine which can be used for the compar
parameter to sort the array alphabetically.
The memory allocated for the array can be deallocated with free(3), by freeing each pointer in the array and then the array itself.
Returns -1 if the directory cannot be opened for reading or if malloc(3) cannot allocate enough memory to hold all the data structures.
malloc(3), opendir(3), qsort(3), dir(5)
alphasort() functions conform to
IEEE Std 1003.1-2008 (“POSIX.1”).
alphasort() functions appeared in
The argument types for
alphasort() and for
the compar argument to
scandir() were originally void
*, then changed to const void *, and then
finally changed by IEEE Std 1003.1-2008
(“POSIX.1”) to their current form of
const struct dirent **. Similarly, the
select() argument to
scandir() was originally struct
dirent * until it was changed to its current form of
const struct dirent *.