redhat man page for alphasort

SCANDIR(3)						     Linux Programmer's Manual							SCANDIR(3)

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 struct dirent **, const struct dirent **));

       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().  If select is NULL, all entries are selected.

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

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
       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

       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
       /* 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
", namelist[n]->d_name);
		   free(namelist[n]);
	       }
	       free(namelist);
	   }
       }

SEE ALSO
       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)