RE: Compute Hash Code -- RPG400-L

Chris, I would think that you might get duplicate results for different inputs. Say, for instance that you had one situation that only consisted of operation 500. Your method would result in a hash of 500 * 1 = 500. Then suppose that you had another situation that consisted of operation 100 & 200. (100 * 1) + (200 * 2) = 100 + 400 = 500. Now, given the result, how are you going to break it back down into the original operations? Is it a 500 operation or a combination of a 100 and 200? Perhaps instead, it would work to use powers of 10 in multiples of three. You could store 10 - 3 digit numbers in one 30,0 packed field. Then operations 100, 200, 300, 400, 500 would be stored as (100 * 10^0) + (200 * 10^3) + (300 * 10^6) + (400 * 10^9) + (500 * 10^12). This way, if your first operation is 500, your result is 500. If your operation set is 100, 200 your result is 200100. If you want the results (It's not really a hash set) to be in order, either determine how many operations are in the set, and start with that factor of 10 and work your way down, or begin with 10^27 and go down from there. Your choice.

 More than likely, others on this list will have much better suggestions.

Duane Johnson

Push, and if you can't push - Pull,
and if you can't pull, get out of the way.


From: Chris_Bougher@xxxxxxxxxxxxx
Reply-To: RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>
To: rpg400-l@xxxxxxxxxxxx
Subject: Compute Hash Code
Date: Wed, 8 Dec 2004 12:56:12 -0500

I need to compute a hash type code for an array of 3 character strings. The
strings are always 3 digit numeric values and do not repeat within a
sequence. I was thinking that I could add the numbers together multiplying
by their position in the list. i.e.

array = '100', '200', '300', '400', '500'
hash = (100 * 1) + (200 * 2) + (300 * 3) + (400 * 4) + (500 * 5) = 5500

Does anyone see any issues with this method? Does anyone have a better
method?


Thanks
Chris Bougher


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