title: PHP - Strtotime - Add hours
body: <p>I have this variable:</p>
  
  <pre><code>$timestamp = strftime("%Y-%m-%d %h:%M:%S %a", time ());
  </code></pre>
  
  <p>I simply want to add three hours and echo it out.</p>
  
  <p>I have seen the way where you can do the 60 * 60 * 3 method or the hard code "+ 3 hours" where it understands the words.</p>
  
  <p>What is the best way of getting this result?</p>