scandir, alphasort - Scan or sorts directory contents
#include <sys/types.h> #include <sys/dir.h>
int scandir(
char *dir_name,
struct dirent *(*name_list []),
int (*compare)(struct dirent **dir1, struct dirent
**dir2) ); int alphasort(
struct dirent **dir1,
struct dirent **dir2 );
Standard C Library (libc)
Points to the directory name. Points to the array of
pointers to directory entries. Points to a user-supplied
function that is called by the scandir() function to
select which entries to include in the array. Points to a
user-supplied function that sorts the completed array.
Points to a dirent structure. Points to a dirent structure.
The scandir() function reads the directory pointed to by
the dir_name parameter. It then uses the malloc() function
to create an array of pointers to directory entries. The
scandir() function returns the number of entries in the
array and, through the name_list parameter, a pointer to
the array.
The select parameter points to a user-supplied function
that the scandir() function calls to select which entries
to include in the array. The selection routine is passed a
pointer to a directory entry and returns a nonzero value
for a directory entry that is included in the array. If
the select parameter is a null value, all directory
entries are included.
The compare parameter points to a user-supplied function
that is passed to the qsort() function to sort the completed
array. If the compare parameter is a null value,
the array is not sorted.
The memory allocated to the array can be deallocated by
freeing each pointer in the array, and the array itself,
with the free() function.
The alphasort() function alphabetically compares the two
dirent structures pointed to by the dir1 and dir2 parameters.
This function can be passed as the compare parameter
to either the scandir() function or the qsort() function.
A user-supplied subroutine may also be used.
The scandir() function returns -1 if the directory cannot
be opened for reading or if the malloc() function cannot
allocate enough memory to hold all the data structures. If
successful, the scandir() function returns the number of
entries found.
The alphasort() function returns the following values:
Less than 0 (zero): The dirent structure pointed to by the
dir1 parameter is lexically less than the dirent structure
pointed to by the dir2 parameter. 0 (zero): The dirent
structures pointed to by the dir1 parameter and the dir2
parameter are equal. Greater than 0 (zero): The dirent
structure pointed to by the dir1 parameter is lexically
greater than the direntstructure pointed to by the dir2
parameter.
Functions: malloc(3), opendir(3), qsort(3)
scandir(3)
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