how to make 404 page in php code example

Example 1: php create 404 error

<?php
http_response_code(404);
include('my_404.php'); // provide your own HTML for the error page
die();

Example 2: how to check website 404 status in php

<?php
$url = 'http://google.com';

if(@file_get_contents($url)){
	
	echo "Website is up";
	
} else {
	
	echo "Website is down";
	
}

?>