php - Extracting a parameter from a URL in WordPress

Question

I am trying to pass a parameter to a WordPress site using a URL - for instance:

www.fioriapts.com/?ppc=1 will be the URL.

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 add_query_arg() but have found nothing on how to extract a parameter. Thanks in advance for any help.

Answer 1

When passing parameters through the URL you're able to retrieve the values as GET parameters.

Use this:

$variable = $_GET['param_name'];

//Or as you have it
$ppc = $_GET['ppc'];

It is safer to check for the variable first though:

if (isset($_GET['ppc'])) {
  $ppc = $_GET['ppc'];
} else {
  //Handle the case where there is no parameter
}

Here's a bit of reading on GET/POST params you should look at: http://php.net/manual/en/reserved.variables.get.php

EDIT: I see this answer still gets a lot of traffic years after making it. Please read comments attached to this answer, especially input from @emc who details a WordPress function which accomplishes this goal securely.