How can the use of undefined entity references be prevented when working with URLs in PHP?

When working with URLs in PHP, the use of undefined entity references can be prevented by properly encoding the URL using the urlencode() function. This function will encode special characters in the URL, preventing any undefined entity references from occurring.

$url = "https://www.example.com/page?name=John Doe";
$encoded_url = urlencode($url);

echo $encoded_url;