my %b_value;
@b_value{@b_array}=();
my @c_array = grep exists $b_value{$_}, @a_array;

##</code><code>##

my $i;
while($i < $#array/2) {
    my $copy = $array[$i];
    $array[$i] = $array[-$i];
    $array[-$i] = $copy;
    ++$i;
}