'#if sizeof(char *) < sizeof(int - (nf)

[jab at uokvax.UUCP]

#R:hocda:-35700:uokvax:3000017:000:226
uokvax!jab    Feb 12 20:00:00 1984

One hack I've seen proposed (many years ago, in the V6 days) was to
be able to write

	#if '\0377' < 0
		code for sign extended chars
	#else
		code for non-sign extended chars
	#endif

This is similar in spirit.

	Jeff Bowles