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.

##</code><code>##

I[1/6/0] need[1/3/2] to[1/7/7] know how[1/3/15] to[2/7/19] compare items within a[1/4/43] string[1/3/45]... I[2/6/55] 
have[1/2/58] dropped a[2/4/71] textfile[1/2/73] into an array[1/2/90], but[1/2/97] now[1/2/101] I[3/6/105] need[2/3/107] to[3/7/112] check[1/2/115] 
whether[1/2/122] words in[1/2/136] that[1/2/139] text[1/3/144] are[1/2/149] repeated[1/2/153] throughout. I[4/6/174] have[2/2/176] split[1/2/181] 
the[1/2/188] text[2/3/192]; as I[5/6/201] only want the[2/2/213] text[3/3/217] to[4/7/222] be[1/2/225] manipulated. Maybe it's 
better to[5/7/260] split[2/2/263] it like this; So[1/3/283] anyway, I[6/6/294] basically need[3/3/306] to[6/7/311] check[2/2/314] 
now[2/2/321] across my[1/3/332] string[2/3/335] whether[2/2/342] any[1/2/350] elements in[2/2/363] my[2/3/366] string[3/3/369] are[2/2/376] repeated[2/2/380], 
and if so[2/3/398], how[2/3/402] many times. I've read a[3/4/428] lot about manipulating arrays[1/3/453], 
but[2/2/462] they're all based on arrays[2/3/487] that[2/2/494] you create yourself, rather 
than arrays[3/3/533] created by opening a[4/4/559] textfile[2/2/561], so[3/3/571] I'm not sure how[3/3/587] to[7/7/591] 
manipulate my[3/3/606] array[2/2/609]. Any[2/2/616] help would be[2/2/631] much appreciated.