#!/usr/bin/perl -w
use strict;
use Data::Dump qw(dump);

my @keys = qw{ a b c d };
my %hash = map { $_++ } @keys;

warn "Dump " . dump( %hash ) . "\n";

##</code><code>##

#!/usr/bin/perl -w
use strict;
use Data::Dump qw(dump);

my @keys = qw{ a b c d };
my %hash = ();
for (@keys) {
    $hash{$_}++;
}
warn "Dump " . dump( %hash ) . "\n";

##</code><code>##

Dump ("c", "d", "a", "b") # first script
Dump ("a", 1, "c", 1, "b", 1, "d", 1) # second script