title: Why does Perl complain "Use of implicit split to @_ is deprecated"?
body: <p>This code triggers the complaint below:</p>
  
  <pre><code>#!/usr/bin/perl 
  use strict;
  use warnings;
  
  my $s = "aaa bbb";
  my $num_of_item = split(/\s+/, $s) ;
  print $num_of_item;
  </code></pre>
  
  <p>When I run the code, Perl complains that "<code>Use of implicit split to @_ is deprecated</code>" . 
  I really have no "context" for the problem, so I expect you help to explain what's wrong with
  the code.</p>