...
 my ($fiop, $length, $data)
    = $string =~ m{<file                 # tag anchor
                   \s+ fiop="([^"]+)"    # (foo)
                   \s+ length="([^"]+)"  # (bar)
                   />                    # end: start file tag
                   \s* (.*?)             # (baz) - note the "nongreedyness" .*?
                   </file>               # end: file tag
                  }x;

 print "$fiop, $length, $data\n";
 ...

##</code><code>##

 
  ...
 (my $notags = $string) =~ s{<file.+?</file>}{};
  print "$notags\n";
  ...