#!/usr/bin/perl

use strict;

my $count = 0;
while(<DATA>) {
    $_ =~ /(foo)/;
    if($1) {
        print "$count: $1 -- $&\n";
        $count ++;
    }
}

exit;

__DATA__
foo
bar
baz
foobar
fjkdlsa
jewklf
fdlkjsa
jfj49i
fjdals;
foo
fjkdsla

##</code><code>##

0: foo -- foo
1: foo -- foo
2: foo -- foo
3: foo -- foo
4: foo -- foo
5: foo -- foo
6: foo -- foo
7: foo -- foo
8: foo -- foo
9: foo -- foo
10: foo -- foo