use strict;
use warnings;

my $string;
{
    local $/;
    $string = <DATA>;
}

my @words = split /[.,;:?! \n]+/, $string;

my $rhWords = {};
my $order = 0;
foreach my $word (@words)
{
    my $lcWord = lc $word;
    push @{$rhWords->{$lcWord}->{order}}, ++ $order;
    $rhWords->{$lcWord}->{count} ++;
}

my %found = ();
$string =~ s
   {
      ([^.,;:?! \n]+)(?{++ $found{lc $1}})
   }
   {
      $1 .
      (
         $rhWords->{lc $1}->{count} > 1 ?
         "[$^R/$rhWords->{lc $1}->{count}/@{[pos()]}]" :
         ""
      )
   }xeg;

print "\n$string\n";

__END__
I need to know how to compare items within a string... I 
have dropped a textfile into an array, but now I need to check 
whether words in that text are repeated throughout. I have split 
the text; as I only want the text to be manipulated. Maybe it's 
better to split it like this; So anyway, I basically need to check 
now across my string whether any elements in my string are repeated, 
and if so, how many times. I've read a lot about manipulating arrays, 
but they're all based on arrays that you create yourself, rather 
than arrays created by opening a textfile, so I'm not sure how to 
manipulate my array. Any help would be much appreciated.