IsUnsigned() function (retiring injured)

[Peter da Silva]

In article <25836 at mimsy.umd.edu> chris at mimsy.umd.edu (Chris Torek) writes:
> Actually, the rule is fairly easy to state:  `In ANSI C, when an
> unsigned type is promoted% to some other type, it becomes signed
> (without changing value) if and only if the new type is actually
> bigger.'  In practise, this means that you have to know whether
> sizeof(short) < sizeof(int) and whether sizeof(char) < sizeof(int).

What is the rationale for this? There's probably a good reason, but at
first glance it seems counterintuitive.
-- 
Peter da Silva.   `-_-'
+1 713 274 5180.   'U`
<peter at ficc.ferranti.com>