varchar/char size

Does someone want to remind me why we allocate the full size for char()
and varchar(), when we really can just allocate the size of the given
string?

I relize char() has to be padded, but why varchar()?

In my experience, char() is full size as defined by create, and
varchar() is the the size of the actual data in the field, like text,
but with a pre-defined limit.

-- 
Bruce Momjian
maillist@candle.pha.pa.us