#!/usr/bin/perl -w
use strict;
my %h1;
$h1{'key1'} = 'foo';
$h1{'key2'} = 'bar';
my @a1 = ( 'key1' , 'key2' , 'not_a_key');
my @a2 = grep defined , @h1{@a1};
print "$_\n" foreach(@a2);