What is the function used in PHP to retrieve the current Windows user (%username%)?

To retrieve the current Windows user (%username%) in PHP, you can use the `getenv()` function to access environment variables. The environment variable `%username%` contains the current Windows user's username. You can retrieve this value by passing `%username%` as the argument to the `getenv()` function.

$current_user = getenv('username');
echo $current_user;