Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!gatech!ncsuvx!csl!harish
From: harish@csl.ncsu.edu (Harish Hiriyannaiah)
Newsgroups: comp.lang.c
Subject: Re: swap(x,y)
Message-ID: <3785@ncsuvx.ncsu.edu>
Date: 28 Aug 89 14:21:11 GMT
Sender: news@ncsuvx.ncsu.edu
Reply-To: harish@csl.UUCP (Harish Hiriyannaiah)
Organization: North Carolina State University
Lines: 28


 I have been reading the swap() discussion with interest, but I am still
 unconvinced about the XOR trick.  Let's review both of them.

 [1]
	 temp = x;
	 x = y;
	 y = temp;

 [2] 
	 x ^= y;
	 y ^= x;
	 x ^= y;

Advantages of [2]:
 (1) Works for any fundamental data type. (char, int, float etc);
 (2) Does not need allocation for temp.

Advantage (1) is of more value than (2). In terms of speed, both are just
about the same.(assuming that x and y are out in memory - BTW, are there
any processors which implement XCHG for memory too, in addition to
registers ?) The allocation for temp on the stack ( assuming a stack
model ) is negligible in terms of allocation time. But in terms of
readability of the code, [2] fails over [1], unless it is properly
documented, which most people fail to do.

harish pu. hi.					harish@ecelet.ncsu.edu
						harish@ecebucolix.ncsu.edu