$ cat ex_sort_odd.pl 
#!/usr/bin/perl
use strict;
use warnings;

my @a;
push @a, int(100*rand) for 1 .. 10;
print "LIST: ", join(" ", @a), "\n";

my @b = sort { $a - $b } @a;
print "ASC:  ", join(" ", @b), "\n";

@b = sort { $b - $a } @a;
print "DESC: ", join(" ", @b), "\n";

$ perl ex_sort_odd.pl
LIST: 27 78 66 70 19 37 48 82 67 90
ASC:  19 27 37 48 66 67 70 78 82 90
DESC: 90 82 78 70 67 66 48 37 27 19