RE: Safe to maintain pointer to errno() ?

Dennis;

P.S. If you put this in a service program it should be compiled with ACTGRP(*CALLER). Found this out the hard way, which may help answer part of your original question.

Duane Christen


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Duane Christen
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-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Dennis Lovelady
Sent: Wednesday, October 13, 2010 11:37 AM
To: 'RPG programming on the IBM i / System i'
Subject: Safe to maintain pointer to errno() ?

Folks, I have often wondered and have never found reference to the internal workings of errno. My specific question is whether it is safe to obtain a pointer to errno only one time, and then reference the based value from then on. It makes sense to me that errno's value would be at a static location and won't float around in memory, but - again - I haven't seen any guarantee of that. So in my programs every time I want to measure success of certain operations, it's the old retrieve-the-address-and-test-the-value approach.
This really is like the C approach except that in C it can be a single instruction ( if (*errno < 1) . ).



Any takers from folks in the know?



Dennis E. Lovelady
AIM/Skype: delovelady MSN: fastcounter@xxxxxxxxxxxx
<http://www.linkedin.com/in/dennislovelady>
www.linkedin.com/in/dennislovelady --
Using Windows is better than eating glass*
- *Depending upon the quality of the glass.



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