{ Copyright (C) 1981 by Bell Laboratories, Inc., and Whitesmiths Ltd. }
{ isalphanum -- true if c is letter or digit }
function isalphanum (c : character) : boolean;
begin
	isalphanum := c in
		[ord('a')..ord('z'),
		 ord('A')..ord('Z'),
		 ord('0')..ord('9')]
end;