In K&R C
(I don't know from ANSI), it was recommended that an int be
whatever type was easiest to deal with.
ISO C section 6.2.5 paragraph 5 says about
the int type:
K&R .NE. ANSI
K&R .NE. ISO
NOTE: "K&R" refers to edition ONE.
Later, K&R wrote a different book to document a different language
(ANSI-C)