while you are connected on any server and while you are on one or more channels, tried to write //echo -a $chan(lol) or //echo -a $chan(-.-) or whichever thing within the two parentheses type (knap) (mint) (hello) etc...
you'll see that the mirc will gave always the number of the channel where you are.
example:
//echo -a $chan(knap) the mirc gave the same result that gave when you write //echo -a $chan(0)
I attend one postreply

It's not a bug. In many mirc identifiers that accept a numeric parameter, a non-numeric argument is taken to mean 0, so the identifier returns the total number of items. In $chan(), that accepts either a number or a valid channel name (ie one that starts with a character in $chantypes), any string that is neither is considered 0.