SCANDIR

Section: Linux Programmer's Manual (3 )
Updated: 1996-04-11
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NAME

scandir, alphasort, versionsort - scan a directory for matching entries

SYNOPSIS

#include <dirent.h>

int scandir(const char *dir, struct dirent ***namelist,
int (*select)(const struct dirent *),
int (*compar)(const void *, const void *));


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

The alphasort() and versionsort() functions can be used as the comparison function for the scandir() function to sort the directory entries into alphabetical order. Although they parameters point to void, they are in fact pointers to pointers (struct dirent**) to two directory entries, a and b, to compare.

alphasort() will order the files with strcoll(3), while versionsort() will use strverscmp(3).

RETURN VALUE

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 considered to be respectively less than, equal to, or greater than the second.

ERRORS

ENOMEM: Insufficient memory to complete the operation.

CONFORMING TO

BSD 4.3

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);
    }
}

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