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RedHat 9 (Linux i386) - man page for versionsort (redhat section 3)

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  com-
       par().	The  former  sorts  directory entries using strcoll(3), the latter using strvers-
       cmp(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  pre-
       cise 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\n", 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), str-
       coll(3), strverscmp(3), telldir(3)

GNU					    2001-12-26				       SCANDIR(3)


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