Character Constants: Any character constant of more
than one character produces a warning. The value of an integral
character constant containing more than one character is computed
by concatenating the 8-bit ASCII code values of the characters,
with the leftmost character being the most significant. For example,
the character constant 'AB'
has the value 256*'A'+'B' = 256*65+66 = 16706.
Only the rightmost four characters participate in the computation.