Q: what is the purpose of $_PHP_SELF?

 Q: what is the purpose of $_PHP_SELF?

Ans: $_SERVER['PHP_SELF'] is a predefined variable in PHP that holds the name of the script that is currently being executed. It can be used to create a form action that points to the same script, allowing the script to process the form data after it has been submitted.

For example, if the current script is example.php, $_SERVER['PHP_SELF'] will contain the string "/example.php". So you can use it as the value of the action attribute in a <form> element, like this:

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">

This will cause the form data to be sent to the same script that is currently being executed, allowing the script to process the form data.

It's important to notice that using $_SERVER['PHP_SELF'] as the action in a form can be a security risk, because it allows a user to submit a form that causes the server-side script to execute arbitrary code by injecting malicious data into the form. To prevent this, you can use htmlspecialchars($_SERVER['PHP_SELF']) when echo it, or use other alternatives like

basename($_SERVER['PHP_SELF'])