How can the absence of the "www" prefix in a URL affect PHP functionality in a website?

When the "www" prefix is absent in a URL, it can affect PHP functionality in a website if the website's PHP code relies on the presence of the "www" prefix for certain functionalities or redirects. To solve this issue, you can use PHP to check the URL and redirect to the correct URL with the "www" prefix if it is missing. 

<?php
// Check if the URL does not contain the "www" prefix
if (strpos($_SERVER['HTTP_HOST'], 'www.') === false) {
    // Redirect to the same URL with the "www" prefix
    header('Location: https://www.' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']);
    exit();
}
?>

Keywords

URL PHP functionality prefix website

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