PHP Get Current URL

I need to get the current url for some purposes, such as;

• Check the url if it is used to be. This is required to prevent dublicated content from different urls in your website.
• Generate social bookmark and like data-href links

It is easy to get the current url in PHP;

<?php 

echo "http://".$_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];

?>

This will give you the exact url of the current page.