#!/usr/bin/env perl 
use strict;
use warnings;

my @array = qw/b d a c/;

my %hash = (
    a  => 200,
    b  => 100,
    c  => 30,
    d  => 40
);

for my $key (sort @array) {
    if ($hash{$key}) {
        print "array element: $key = $hash{$key} inside \%hash\n";
    }
}