Availability:built-in
code_type(?Code, 
?Type)As char_type/2, 
but uses character codes rather than one-character atoms. Please note 
that both predicates are as flexible as possible. They handle either 
representation if the argument is instantiated and will instantiate only 
with an integer code or a one-character atom, depending of the version 
used. See also the Prolog flag
double_quotes, atom_chars/2 
and atom_codes/2.