IsUnsigned() function?

[Karl Heuer]

In article <1990Jul16.214155.5087 at Neon.Stanford.EDU> jhsu at Neon.Stanford.EDU (Jeffrey H. Hsu) writes:
>How would you write a space efficient algorithm/function in C that
>takes in an integer and returns 0 if signed and 1 if unsigned?

Define your terms.  Is this to be a function or a macro?  If a function, then
its argument must have a type known at compile-time: what type is it?  Is the
goal to determine the signedness of the type of the argument, or the value?

A non-trivial specification is to write a macro to find the signedness of the
(promoted) type of its argument expression.  One way to do this is
	#define IsUnsigned(x) (((x)*0-2)/2+1 != 0)

Karl W. Z. Heuer (karl at kelp.ima.isc.com or ima!kelp!karl), The Walking Lint