Path: utzoo!utgpu!water!watmath!clyde!rutgers!princeton!udel!gatech!hubcap!ncrcae!ncr-sd!hp-sdd!hplabs!hpcea!hpcilzb!tedj
From: tedj@hpcilzb.HP.COM (Ted Johnson)
Newsgroups: comp.lang.c
Subject: Simple question about:  ~
Message-ID: <1620006@hpcilzb.HP.COM>
Date: 25 Jan 88 07:27:03 GMT
Organization: HP Design Tech Center - Santa Clara, CA
Lines: 33


Could someone please explain why the following statements both give the
same answer?

	short int x, y = 12;

		x = -y -1;


vs.

	short int x, y = 12;

		x = ~y;	


Both ways end up assigning x the value of -13.  K&R say something about
the  ~ operator taking the one's complement of a number, but I didn't
follow their explanation...  

The only reason I ask is because I saw two different programs compute the 
same function in two different ways, and I want to know if they are really 
doing the same thing or if this is a special case where both functions give
the same answer. 

Thanks in advance!

-Ted

P.S. This was on a machine where a short int is 16 bits.