#! /usr/bin/perl -w

use strict;

my @letters = qw(a b c d e); #'a'..'e' also works,
                             #but I didn't want to add
                             #a red herring ;-)
print '  $_ |  $r |  $.'."\n";

for (@letters) {
    if(my $r = /a/../e/) {
        printf "%4s |%4s |%4s\n", $_, $r, $.;
    }

    $.++;    # ok, this is silly
        # but I'm making a point ;-)
}

print "\n", '  $_ |  $r |  $.'."\n";
while (<DATA>)
{
    chomp;
    if(my $r = /a/../e/) {
        printf "%4s |%4s |%4s\n", $_, $r, $.;
    }
}
  
__DATA__
a
b
c
d
e

##</code><code>##

  $_ |  $r |  $.
Use of uninitialized value in printf at ./r2.pl line 12.
   a |   1 |    
   b |   2 |   1
   c |   3 |   2
   d |   4 |   3
   e | 5E0 |   4

  $_ |  $r |  $.
   a |   1 |   1
   b |   2 |   2
   c |   3 |   3
   d |   4 |   4
   e | 5E0 |   5