Redirecting from HTTP to HTTPS with PHP

Try something like this (should work for Apache and IIS):

if (empty($_SERVER['HTTPS']) || $_SERVER['HTTPS'] === "off") {
    $location = 'https://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    header('HTTP/1.1 301 Moved Permanently');
    header('Location: ' . $location);
    exit;
}

This is a good way to do it:

<?php
if (!(isset($_SERVER['HTTPS']) && ($_SERVER['HTTPS'] == 'on' || 
   $_SERVER['HTTPS'] == 1) ||  
   isset($_SERVER['HTTP_X_FORWARDED_PROTO']) &&   
   $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https'))
{
   $redirect = 'https://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
   header('HTTP/1.1 301 Moved Permanently');
   header('Location: ' . $redirect);
   exit();
}
?>