scandir.3c (2010 09)

s
scandir(3C) scandir(3C)
NAME
scandir( ), alphasort( ) - scan a directory
SYNOPSIS
#include <dirent.h>
extern int scandir(
const char *dirname,
struct dirent ***namelist,
int (*select) (const struct dirent *),
int (*compar) (const struct dirent **,
const struct dirent **
)
);
int alphasort(
const struct dirent **d1,
const struct dirent **d2
);
DESCRIPTION
scandir() reads the directory dirname and builds an array of pointers to directory entries using mal-
loc() (see malloc (3C)). It returns the number of entries in the array and a pointer to the array through
namelist .
The select parameter is a pointer to a user-supplied subroutine which is called by
scandir() 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 select is null,
then all the directory entries will be included.
The compar parameter is a pointer to a user-supplied subroutine which is passed to qsort (3C) to sort the
completed array. If this pointer is null, the array is not sorted.
alphasort() is a routine which can
be used for the compar parameter to sort the array alphabetically.
EXTERNAL INFLUENCES
Locale
The
LC_COLLATE category determines the collation ordering used by alphasort().
The
LC_CTYPE category determines the interpretation of bytes in the file name portion of directory
entries as single- and/or multi-byte characters by the alphasort() function.
Results are undefined if the locales specified by the
LC_COLLATE and LC_CTYPE
categories use
different code sets.
International Code Set Support
Single- and multi-byte character code sets are supported for
alphasort().
RETURN VALUE
If successful,
scandir() returns the number of directory entries selected, and through the namelist
parameter returns a pointer to the array. scandir() returns −1, if the directory cannot be opened for
reading or cannot allocate enough memory to hold all the data structures.
APPLICATION USAGE
scandir() uses malloc() to allocate memory for the array associated with the namelist pointer. If
the return value of scandir() is greater than or equal to zero (0), memory allocated for the namelist
pointer needs to be freed by the application using free() (see malloc (3C)) by first freeing each pointer
in the array followed by the array itself.
EXAMPLES
The example program below scans the
/tmp directory. It does not exclude any entries since select is
NULL. The contents of namelist are sorted by alphasort(). It prints out how many entries are in
/tmp and the sorted entries of the /tmp directory. The memory used by scandir() is returned using
free().
#include <sys/types.h>
#include <stdio.h>
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1