Redirect http website access to the https prefix website in codeigniter

//Place the below code in the index.php file of codeigniter framework

<?php 

if($_SERVER['HTTPS']!="on"){

if(substr($_SERVER['REQUEST_URI'],0,1)=='/'){

header('Location: https://'.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']);

}else{

header('Location: https://'.$_SERVER['HTTP_HOST'].'/'.$_SERVER['REQUEST_URI']);

}

}