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From: spencer@osu-cgrg.UUCP (Steve Spencer)
Newsgroups: comp.lang.c
Subject: Re: Writing readable code
Message-ID: <854@osu-cgrg.UUCP>
Date: Sat, 4-Jul-87 09:12:03 EDT
Article-I.D.: osu-cgrg.854
Posted: Sat Jul  4 09:12:03 1987
Date-Received: Sat, 4-Jul-87 20:29:00 EDT
References: <8286@ut-sally.UUCP> <7001@alice.UUCP> <364@sol.ARPA> <1213@carthage.swatsun.UUCP>
Organization: Computer Graphics Research Group, Columbus OH
Lines: 48
Summary: It's not ALWAYS that easy...

In article <1213@carthage.swatsun.UUCP>, rice@swatsun (Dan Rice) writes:
> 
> center = s2->o;
> 
> if I plan to use s2->o several times?  Thanks for any help.
> -- 
> - Dan Rice, Swarthmore College, Swarthmore PA 19081
> ...!sun!liberty!swatsun!rice
>  ...!seismo!bpa!swatsun!rice

Yes, I would (and have) used something like what you describe when I have to
use the current values in s2->o many times in a function (example: if s2->o
was the intersection point of a ray with a sphere in a ray-tracing program
and the function in which I was working was a shader. :-))

BUT......

Some C compilers will let you get away with 

   center = s2->o;

(i.e.: structure assignments)

But some won't.  Your best bet for non-flakiness is:

   center.x = (s2->o).x;
   center.y = (s2->o).y;
   center.z = (s2->o).z;

Sure, it's three statements instead of one, but 

 (1) You are certain that all three values were assigned correctly.
 (2) If you had to access (as you speculated) s2->o.x multiple times,
     you are saving yourself cycles in the long run.

Hope I helped...


steve

-- 
...I'm growing older but not up...       - Jimmy Buffett

Stephen Spencer, Graduate Student
The Computer Graphics Research Group
The Ohio State University
1501 Neil Avenue, Columbus OH 43210
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