perl -le 'print for sort {$a <=> $b} qw(bbb1 aaa2 ccc3 xxx15 def159)'
bbb1
aaa2
ccc3
xxx15
def159

##</code><code>##

foreach my $key ( sort {$a <=> $b} $q->param() ) {
    my $value = $q->param($key);
    # now do whatever with $value
    ...
}