Valid User check function

[The One]

Is there any function which checks if a given username is a registered user or not?

[Rudolf]

in Subs-Members.php
bool isReservedName(string name, int ID_MEMBER = 0, bool is_name = true)

[The One]

Actually I need to find out if a user is currently logged in and performing some action on the board. Only if they are not doing so do I need to check if I need to log them in or not.

What are the global variables that contain the present user information?

[Rudolf]

The $context array
for the user - $context['user']

[The One]

Where is this array declared and what are the contents of the user array in $context (i.e $context['user'] array)?