#!usr/bin/env perl

use warnings;
use strict;

while (<DATA>) {
    my @words = split ();
    my @pWords = grep {/p/i} @words;

    print "Line $. contains ";
    if (@pWords) {
        print "the following words containing p: @pWords\n";
    } else {
        print "no words containing p\n";
    }
}

__DATA__
CPAN stands for comprehensive Perl Archive Network.
^ and $ are used as anchors in a regular expression.
/pattern/ is a pattern match operator.
Perl is very easy to learn.
Enter 'H' or 'h' for help.