print "${line}";

##</code><code>##

#!/usr/bin/perl

my $ans;
my $currentline;
my @data;

print "Letter? ";
$letter = <STDIN>;
chomp $letter;
open (DATA, "books.txt");
@data = <DATA>;
$currentline = 0;
foreach $data(@data) {
  $line = $data[$currentline];         # there are brackets around $currentline
  if ($line =~ /^$letter/i) {
    print $line;
  }
  $currentline++
}

##</code><code>##

#!/usr/bin/perl -w

use strict;

print "Letter? ";
my $letter = <STDIN>;   
chomp $letter;
open (DATA, "books.txt") or die "error opening file $!";
my $line;
foreach $line(<DATA>) {
  if ($line =~ /^$letter/i) {
    print $line;
  }
}  
close DATA;