#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
use Benchmark qw/cmpthese timethese/;

my($max,%h);
$max=1000000;
%h=map { $_ => "test" } (1 .. $max);
sub with_keys{
    foreach my $k (keys %h){
        #no proc
    }
}
sub with_each{
    while( my($k,$v)=each %h){
        #no proc
    }
}

cmpthese(
    timethese(
        100,
        {
            'with keys'=> &with_keys,
            'with each'=> &with_each,
        }
    )
);