Code used by WordPress to determine whether a user is logged on

I know little about WordPress. The code used by WordPress to determine whether a user is logged on. For more information, see. WordPress

Is_user_logged_in ()
Description
Returns a boolean value of true or false based on whether the current visitor logs on.

Parameters
This function does not accept any parameters.

Usage
The code is as follows:


Example
Use the is_user_logged_in () function to display different output results in the topic file based on the logon status of the current visitor.
The code is as follows:
If (is_user_logged_in ()){
Echo 'Welcome, registered user! ';
} Else {
Echo 'Welcome, visitor! ';
}
?>

Reference link:Function Reference/is user logged in