scandir
NAME
scandir, alphasort, versionsort - scan a directory for matching entries
SYNOPSIS
#include <dirent.h>
I int scandir(const char * dir , struct dirent *** namelist ,
I int(* filter )(const struct dirent *),
I int(* compar )(const struct dirent **, const struct dirent **));
I int alphasort(const void * a , const void * b );
I int versionsort(const void * a , const void * b );
DESCRIPTION
The
R scandir ()
function scans the directory
dir, calling
filter() on each directory entry.
Entries for which
filter() returns non-zero are stored in strings allocated via
malloc(3),
sorted using
qsort(3)
with the comparison
function
compar(), and collected in array
namelist
which is allocated via
malloc(3).
If
filter is NULL, all entries are selected.
The
R alphasort ()
and
R versionsort ()
functions can be used as the comparison function
R compar ().
The former sorts directory entries using
strcoll(3),
the latter using
strverscmp(3)
on the strings
(*a)->d_name and
(*b)->d_name.
RETURN VALUE
The
R scandir ()
function returns the number of directory entries
selected or -1 if an error occurs.
The
R alphasort ()
and
R versionsort ()
functions return an integer less than, equal to,
or greater than zero if the first argument is considered to be
respectively less than, equal to, or greater than the second.
ERRORS
ENOMEM
Insufficient memory to complete the operation.
CONFORMING TO
None of these functions is in POSIX.1-2001, but
R alphasort ()
and
R scandir ()
are under consideration for a future revision to POSIX.1.
The functions
R scandir ()
and
R alphasort ()
are from 4.3BSD, and have been available under Linux since libc4.
Libc4 and libc5 use the more precise prototype
int alphasort(const struct dirent ** a,
const struct dirent **b);
but glibc 2.0 returns to the imprecise BSD prototype.
The function
R versionsort ()
is a GNU extension, available since glibc 2.1.
Since glibc 2.1,
R alphasort ()
calls
strcoll(3);
earlier it used
strcmp(3).
EXAMPLE
/* print files in current directory in reverse order */
#include <dirent.h>
int
main(void)
{
struct dirent **namelist;
int n;
n = scandir(".", &namelist, 0, alphasort);
if (n < 0)
perror("scandir");
else {
while (n--) {
printf("%s\n", namelist[n]->d_name);
free(namelist[n]);
}
free(namelist);
}
}
SEE ALSO
ČLÁNKY DO MAILU