Simplest way is to search the text for each word in the string, since this doesn't require counting all the words in the text. Depending on how many words you're looking for, you can probably also speed things up by lowercasing the text before the search: 
use strict;
use warnings;

my ($text, $find, $c);
read(DATA, $text, 1024); $text = lc($text);

$find = 'cried louder and louder';
for (split / +/, $find) {
    $c++ while $text =~ /$_/g;
} print $c;

__DATA__
Now it so happened that on one occasion the princess's golden ball
did not fall into the little hand which she was holding up for it,
but on to the ground beyond, and rolled straight into the water.  The
king's daughter followed it with her eyes, but it vanished, and the
well was deep, so deep that the bottom could not be seen.  At this
she began to cry, and cried louder and louder, and could not be
comforted.  And as she thus lamented someone said to her, "What ails
you, king's daughter?  You weep so that even a stone would show pity."

[download]
Just a rough draft. I'll let other people worry about preprocessing of the search string, whether to search based with or without word boundaries (I prefer not), etc.

In reply to Re: Counting the frequency of words in a string by TedPride
in thread Counting the frequency of words in a string by cez

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