SCANDIR(3) Linux Programmer's Manual SCANDIR(3)
NAME
scandir, alphasort, versionsort - scan a directory for matching entries
SYNOPSIS
#include<dirent.h>
intscandir(constchar*dir,structdirent***namelist,
int(*select)(conststructdirent*),
int(*compar)(conststructdirent**,conststructdirent**));
intalphasort(constvoid*a,constvoid*b);
intversionsort(constvoid*a,constvoid*b);
DESCRIPTION
The scandir() function scans the directory dir, calling select() on
each directory entry. Entries for which select() returns non-zero are
stored in strings allocated via malloc(), sorted using qsort() with the
comparison function compar(), and collected in array namelist which is
allocated via malloc(). If select is NULL, all entries are selected.
The alphasort() and versionsort() functions can be used as the compari-
son function compar(). The former sorts directory entries using str-
coll(3), the latter using strverscmp(3) on the strings (*a)->d_name and
(*b)->d_name.
RETURNVALUE
The scandir() function returns the number of directory entries selected
or -1 if an error occurs.
The alphasort() and versionsort() functions return an integer less
than, equal to, or greater than zero if the first argument is consid-
ered to be respectively less than, equal to, or greater than the sec-
ond.
ERRORS
ENOMEM Insufficient memory to complete the operation.
CONFORMINGTO
None of these functions is in POSIX. The functions scandir() and
alphasort() are from BSD 4.3, and have been available under Linux since
libc4. Libc4 and libc5 use the more precise prototype
intalphasort(conststructdirent**a,conststructdirent**b);
but glibc 2.0 returns to the imprecise BSD prototype.
The function versionsort() is a GNU extension, available since glibc
2.1. Since glibc 2.1, alphasort() calls strcoll(3); earlier it used
strcmp(3).
EXAMPLE
/* print files in current directory in reverse order */
#include <dirent.h>
main(){
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);
}
}
SEEALSO
closedir(3), fnmatch(3), opendir(3), readdir(3), rewinddir(3),
seekdir(3), strcmp(3), strcoll(3), strverscmp(3), telldir(3)
GNU 2001-12-26 SCANDIR(3)
Take our 
