SCANDIR

NAME

SYNOPSIS

#include <dirent.h>

int scandir(const char *dirp, struct dirent ***namelist,
int (*filter)(const struct dirent *),
int (*compar)(const struct dirent **, const struct dirent **));


int alphasort(const void *a, const void *b);

int versionsort(const void *a, const void *b);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

scandir(), alphasort(): _BSD_SOURCE || _SVID_SOURCE
versionsort(): _GNU_SOURCE  

DESCRIPTION

The alphasort() and versionsort() functions can be used as the comparison function 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 alphasort() and 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.

VERSIONS

CONFORMING TO

The functions scandir() and 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 versionsort() is a GNU extension, available since glibc 2.1.

Since glibc 2.1, alphasort() calls strcoll(3); earlier it used strcmp(3).  

EXAMPLE

#define _SVID_SOURCE
/* 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

COLOPHON