Re: IFEQ ANDEQ vs IFEQ OREQ

[William Washington III <w.washington3@xxxxxxxxxxxxx>]

Sorry, I'm a bit behind on my reading...

Frank, if you change the "EQ" to "NE" in your second example and place an ELSE 
statement before your MOVE statement, then you will have functionally identical 
code snippets.
 
You can find more information on this by going to Google and entering 
"DeMorgan's Theorem"...  (the complement of a conjunction is the disjunction of 
the complements)... Digital electronics guys know this stuff, but it is very 
useful to software guys too.
 
Depending on your data, you can determine which method (AND or OR) is better.  
If the majority of the data can "short-circuit" the expression, that is the way 
I'd code it.  (Keeping in mind clarity and maintainability, of course.)
 
A "short circut" occurs if you determine the truth of the expression without 
needing to evaluate the complete expression.  If you have a series of "ANDs", 
and you hit a false condition, you don't have to continue to evaulate the whole 
thing.  There is a comparable situation when using "ORs".


date: Thu, 11 Dec 2003 15:10:19 -0600
from: fkany@xxxxxxxxxxxxxxxxxx
subject: IFEQ ANDEQ vs IFEQ OREQ


Will Example 1 and Example 2 have the same effect?

Example 1:
C FHSSUF IFEQ 'XP'
C FHSSUF OREQ 'AC'
C FHSSUF OREQ 'GS'
C MOVEL$MSG,225 #EMSG P
C END

Example 2:
C FHSSUF IFEQ 'XP'
C FHSSUF ANDEQ'AC'
C FHSSUF ANDEQ'GS'
C MOVEL$MSG,225 #EMSG P
C END

Thanks,

Frank



=========================
William Washington III
Njia Systems Incorporated
w.washington3@xxxxxxxxxxxxxxx
312-719-0519
=========================