This will also work for counting words (aka occurences of a pattern in a string):

#!/usr/bin/perl

use strict;
use warnings;

read DATA, my $text, 40;

### this is the important line ###
my $wordcount = () = $text =~ /test/gi;

print $wordcount;

__DATA__
TEST
tester
testing
asdf lalala greatest
[download]

Update: The while++ solution previously posted takes half the time to run as this one. Can anyone explain why?