php get the previous page url from link code example

Example: how to get the link of the current page in php

<?php  
    if(isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on')   
         $url = "https://";   
    else  
         $url = "http://";   
    // Append the host(domain name, ip) to the URL.   
    $url.= $_SERVER['HTTP_HOST'];   
    
    // Append the requested resource location to the URL   
    $url.= $_SERVER['REQUEST_URI'];    
      
    echo $url;  
  ?>