(unsigned) -1 yields all 1s

[Rick Genter]

> 	Actually, I think (unsigned) -1 does have to give you a bit pattern of
> all 1's.  I can not find an explicit reason, but I can deduce this from the
> following: 
> [...]
> 	3.  The value in the range 0 to 2^n-1 (inclusive) congruent mod 2^n
> 	to -1 is 2^n-1.  In straight binary notation this value is repre-
> 	sented as all 1's.

This assumes your machine is in straight binary notation.  If your machine
uses one's complement notation (CDC Cyber?), -0 is represented as all ones.
					- Rick
--------
Rick Genter 				BBN Laboratories Inc.
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