Liz was absolutely right. The $1 .. $3 variables are reset after the second regexp.

To fix the problem, save your $1 .. $3 variables in temporary local variables.

use strict;
use warnings;
my $str = "Title: Learning Perl  Author: Schwartz, Randal L. ISBN: xxx
+x";
if ($str =~ /^Title: (.*)\s+Author: (.*)\s+ISBN: (.*)/) {
  my ($title, $author, $isbn) = ($1, $2, $3);
  $author =~ s/\.//g; # Remove full stops (periods)
  print "<$title><$author><$isbn>";
}
[download]