What is the purpose of using ob_get_clean in PHP and how does it affect constant variables?

When using ob_get_clean in PHP, the purpose is to capture the output buffer, clean (erase) it, and then return the buffer as a string. This function is often used to capture the output of a PHP script without sending it to the browser immediately. When dealing with constant variables, using ob_get_clean does not affect them as constants are defined once and cannot be changed or unset.

ob_start();

// Your PHP code here

$output = ob_get_clean();

// Process $output as needed