Unique Character Count - perl

Question

Hi I an extreme novice and I need help on what I should type so that the unique character count is displayed based on what the user inputs from their keyboard
I already have it set up to show the character count in the string
Here is the Code:
#!C:\Strawberry\perl\bin\perl
use strict;
use warnings;
print "Input Username";
my $str = <>;
chomp ($str);
print "You have typed: $str\n";
my $str_length = length($str);
print "Total Characters = " . $str_length . "\n";
exit;

Answer 1

You can use this function to get what you need:
sub func($) { my ($str, %hash) = shift; $hash{$_}++ for split //, $str; (length $str, scalar keys %hash) }
and this if you need to get count of certain char:
sub uniq_ch_count($$) { my ($ch, $str, %hash) = #_; $hash{$_}++ for split //, $str; $hash{$ch} }
EXAMPLE 1:
my ($chars_count, $uniq_chars_count) = func('one two three four');
print $chars_count . " " . $uniq_chars_count . "\n";
OUTPUT:
18 10
EXAMPLE 2:
print uniq_ch_count('d', "asdjkasdjd sdfj d ") . " " . uniq_ch_count(' ', "asdjkasdjd sdfj d ") . "\n";
OUTPUT:
5
3

Answer 2

The simplest method would be to use a hash:
# split the string into an array of characters
my #chars = split //, $str;
# lists of values can be assigned to multiple indexes at once
# here we assign each character an empty value, but since hash
# keys are unique in nature, every subsequent assignment overwrites
# the first.
my %uniq;
#uniq{#chars} = ();
# next get the list of keys from the hash and treat that list as
# a scalar which gives you the count
my $count = scalar keys %uniq;
See: http://perldoc.perl.org/perldata.html#Slices

Answer 3

OK, so the magic keyword here - as far as Perl is concerned is 'unique'. Because that usually means a hash is the tool for the job.
In perl, a hash is a set of key-value pairs, which means it's great for counting numbers of unique items.
So if you take your string, and split it into characters:
my %count_of;
foreach my $character ( split ( '', $str ) ) {
$count_of{$character}++;
}
You can then print out %count_of:
foreach my $character ( keys %count_of ) {
print "$character = $count_of{$character}\n";
}
But because keys %count_of gives you an array containing each 'key' - one of the nice tricks in perl, is an array in a scalar context, is just a number representing the number of elements. So you can do:
print scalar keys %count_of, " unique characters in $str\n";