Musar Corporation wrote, on Thursday, February 12, 2004 8:57 AM
: I had some code that was giving me trouble. I wanted a program to
: perform some function as long as two conditions did not exist. My
: original code was:
:
: if ($some_value ne $some_input_value && $another_value ne
: $another_input_value) {
:
: do something;
:
: }
:
: I fixed the problem by changing it to:
:
: unless ($some_value eq $some_input_value && $another_value eq
: $another_input_value) {
:
: do something;
:
: }
Brush up on your Boolean logic. When you distribute (or "factor out")
not from "and" or "or", the sense changes. That is:
(Not A And Not B) is equivalent to Not (A Or B).
Look at the truth tables (something I do a lot when trying to reduce a
complicated conditional):
A B !A&&!B A||B
1 1 0 1
1 0 0 1
0 1 0 1
0 0 1 0
What you started with was !A && !B ("as long as two conditions did not
exist", so the expression was a correct translation of your English
requirement); since you wanted the latter, your English requirement
should have been something like "as long as both conditions weren't met."
Good luck
Joe
==============================================================
Joseph P. Discenza, Sr. Programmer/Analyst
mailto:[EMAIL PROTECTED]
Carleton Inc. http://www.carletoninc.com
574.243.6040 ext. 300 fax: 574.243.6060
Providing Financial Solutions and Compliance for over 30 Years
***** Please note that our Area Code has changed to 574! *****
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