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From: tim@amdcad.UUCP
Newsgroups: comp.lang.c
Subject: Re: short circuit evaluation
Message-ID: <14479@amdcad.UUCP>
Date: Sun, 25-Jan-87 13:19:30 EST
Article-I.D.: amdcad.14479
Posted: Sun Jan 25 13:19:30 1987
Date-Received: Mon, 26-Jan-87 01:52:50 EST
References: <425@bobkat.UUCP> <102600001@datacube> <34@umich.UUCP> <5178@mimsy.UUCP>
Reply-To: tim@amdcad.UUCP (Tim Olson)
Organization: Advanced Micro Devices, Sunnyvale, California
Lines: 30

In article <5178@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
	(OFF is all zeros, ON is all ones)
+---------------------------------------
|	&	1.  Left side evaluated.  If OFF, evaluation stops;
|		    result is OFF.  If not, right side evaluated,
|		    and both results ANDed.
|		2.  Left side evaluated.  Right side evaluated.
|		    Results ANDed.
|		3.  Right side evaluated.  If OFF, evaluation stops;
|		    result is OFF.  If not, left side evaluated, and
|		    both results ANDed.
|
|	|	1.  Left side evaluated.  If ON, evaluation stops;
|		    result is ON.  If not, right side evaluated,
|		    and both results ORed.
|		2.  Left side evaluated.  Right side evaluated.
|		    Results ORed.
|		3.  Right side evaluated.  If ON, evaluation stops;
|		    result is ON.  If not, left side evaluated, and
|		    both results ORed.
+---------------------------------------
What about if either the left side expression or the right side
expression contained a side-effect (or a procedure call, which also may
have a side-effect)?  These cannot be short-circuited when bit-wise
operators are used.

	-- Tim Olson
	Advanced Micro Devices

	"We plan products, not lunches"