#!/usr/bin/perl -w
use strict;

my @a = (4,5,1,2);
print "@a\n";

sort_ref_2_array (\@a);
print "@a\n";

sub sort_ref_2_array
{
   my $aref = shift;
   @$aref = sort @$aref;
}
__END__
prints:
4 5 1 2
1 2 4 5