PHP http_response_code() Function

Set the HTTP response status code to 404:

<?php
http_response_code(404);
?>

Definition and Usage

The http_response_code() function sets or returns the HTTP response status code.

http_response_code( code)

Parameter	Description
code	Optional. Specifies a response code (like 404)

Return Value:	If code is set, the previous status code is returned. If code is not set, the current status code is returned
PHP Version:	5.4+