title: Extracting a parameter from a URL in WordPress
body: <p>I am trying to pass a parameter to a WordPress site using a URL - for instance:</p>
  
  <p><code>www.fioriapts.com/?ppc=1</code> will be the URL.  </p>
  
  <p>I am intending to write a function in the functions.php file but the mechanics of how to extract a parameter in WordPress is beyond me.  I am finding a lot of examples on how to add a parameter to a URL using the function <code>add_query_arg()</code> but have found nothing on how to extract a parameter.  Thanks in advance for any help.  </p>