#!/usr/bin/perl -w

use strict;
use diagnostics;

my $hash = {  key1 => 'value1',
              key2 => 'value2',
              key3 => 'value3',
              key1 => 'value3',
              key1 => 'value33',
              key1 => 'value3',
              key2 => 'value3',
              key2 => 'value3',
              key4 => 'value3',
              key4 => '23232',
           };

#foreach (keys %{$hash})  {
#    print "$_ => ${$hash}{$_}\n";
#}

my %hist;
foreach (keys %{$hash}) {
   $hist{$_}++ for $_;
}


foreach (keys %hist) {
    print "$_ , $hist{$_}\n";
}



print "size of hash: " , keys(%{$hash}) . "\n";

././././perl.hash.basic.2
key2 , 1
key1 , 1
key4 , 1
key3 , 1
size of hash: 4
[download]

Now there are two passes over the list, and the situation isn't going 
+to get any prettier from here. What you want is basically a histogram
+ of the data, and you can get that with a hash:

    my %histogram;
    $histogram{$_}++ for @list;

This hash associates each individual item with its count, and it only 
+traverses the list once.

In a recent case, I was looking at a list of tags associated with vari
+ous photographs. To lay out the data for display, it was useful to kn
+ow how many different tags there are in the list. I could get that si
+mply from the number of keys in the histogram:

    $unique = keys %histogram;

I could also delete the duplicates and end up with a list of the uniqu
+e tags:

    @unique = keys %histogram;
[download]

Number of keys is correct. Hash keys are unique. While you can say

my %hash = (
    key => 'foo',
    key => 'bar',
    key => 'quux',
    key => 'fizz',
    key => 'buzz',
);
[download]

in the sense that its's legal and perl won't complain, you end up with %hash containing just one entry. Each assignment overrides the previous one, and you have

%hash = (
     key => 'buzz',
);
[download]

finally.

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

can someone please help me with this? I do not understand why it's not giving me the each counted key.. it's just giving me 1.. what am I missing??

#!/usr/bin/perl -w

use strict;
use diagnostics;
use Data::Dumper;

my %hash = (  key1 => 'value1',
              key2 => 'value2',
              key3 => 'value3',
              key3 => 'value3',
              key3 => 'value3',
              key1 => 'value3',
              key1 => 'value33',
              key1 => 'value3',
              key1 => 'value3',
              key2 => 'value3',
              key2 => 'value3',
              key2 => 'value3',
              key4 => 'value3',
              key4 => '23232',
              key5 => '23232',
              key6 => '23232',
              key6 => '23232',
           );
my %hist;
foreach (sort keys %hash) {
   $hist{$_}++;
}

print Dumper(%hist);


__END__
foreach (sort keys %hist) {
   print "$_ => $hist{$_}\n";
}


$VAR1 = 'key5';
$VAR2 = 1;
$VAR3 = 'key2';
$VAR4 = 1;
$VAR5 = 'key6';
$VAR6 = 1;
$VAR7 = 'key4';
$VAR8 = 1;
$VAR9 = 'key1';
$VAR10 = 1;
$VAR11 = 'key3';
$VAR12 = 1;
[download]

A hash is like an array but the index can be text instead of a number. so when you write

my %hash = (  key1 => 'value1',
              key2 => 'value2',
              key3 => 'value3',
              key3 => 'value3',
              key3 => 'value3',
              key1 => 'value3',
[download]

the second time you do key1 => ... it will overwrite any earlier value of key1.

There will only ever be one value associated with each key, so when you

foreach (sort keys %hash) {
   $hist{$_}++;
}
[download]

each key will be unique, so the count will be one for each of them

You need to study hashes more. Perhaps perldsc will be of help