How to find the Current URL in PHP

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How to find the current Domain in PHP?

If you need the current domain of the site/url .Here is the sample code

<?php
// Using HTTP_HOST

$domain_name = $_SERVER['HTTP_HOST'];
echo $domain_name;
?>

if the current url structure is:http://redirect4.xyz. Remember http://www. part is excluded. The output will be phpfresher.com
If you need to make the link please concatenate the http://www. part with the output