my %country_names = (
     "AF" => "Afghanistan",
     "AX" => "Aland Islands",
     "AL" => "Albania",
     "DZ" => "Algeria",
     "AS" => "American Samoa",
     "AD" => "Andorra",
);

my @intl_files = <DATA>;
chomp @intl_files; # not needed when using opendir/readdir

#map removes the ".txt" file suffix
#sort compares country names, not codes

my @sorted =
    sort { $country_names{ $a } cmp $country_names{ $b } }
    map  { substr( $_, 0, rindex( $_, '.' ) ) } @intl_files;

foreach my $file ( @sorted ) {
    print "<option value=\"$file\">$country_names{$file}</option>\n";
}

__DATA__
AL.txt
DZ.txt
AS.txt