PHP Reload div's content on link click - php

Question

I'd like to reload a specific div if you click on a link with PHP.
HTML Code:
<nav>
Register
Login
</nav>
<div class="content">
//Reload Content here
<p>That's a test paragraph for the start page</p>
</div>
And now I want to include the page from the href on click into the div.content
How can I catch a link click in php? Is this possible? And how can I include the page into my div.content?
Thanks!

Answer 1

You might want to look into using Jquery and AJAX if you want to achieve this without a page reload... Otherwise you might want to use a PHP GET request as follows:
<nav>
Register
Login
</nav>
<div class="content">
<?php
if (isset($_GET['content'])) {
if (file_exists($_GET['content'] . '.php')) {
require($_GET['content'] . '.php');
}
}
?>
<p>That's a test paragraph for the start page</p>
</div>

Answer 2

PHP code is executed on the server, and cannot reload a <div> widhout rendering the whole page. If you absolutly want to use PHP to do this, you need to make an <iframe> inside the <div class=content> and reload that.
URL parameters is stored in the $_GET variable.
For example: foo.com?page=bar can be retrieved with $_GET['page']
<?php
echo $_GET['page']; // will return "bar"
?>
Example in pure PHP without <iframe>
<nav>
Register
Login
</nav>
<div class="content">
<?php
if(isset($_GET['page']))
{
// Includes the content. # is for supressing errors if the file is not found.
// Can be solved with is_file();
// http://php.net/manual/en/function.is-file.php
#include "/path/to/file/".$_GET['page'].".php";
}
?>
</div>
This is not the most secure way of doing it, because you can manipulate the URL to include other PHP files in your system, but you get the idea.