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Author Topic: Quick Sort  (Read 2101 times)
david9c
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« on: March 28, 2004, 02:17:48 PM »

Quick Sort

Where can I find a text description of the logic for quicksort?

I have two sample programs that sort an array, but I'm
interested in sorting random access files, large files.

d12connelly@yahoo.com
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whitetiger0990
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« Reply #1 on: March 28, 2004, 04:22:50 PM »

this thread helps
http://forum.qbasicnews.com/viewtopic.php?t=1937

it's basically
Code:
If a(x) > a(x+1) then swap a(x), a(x+1)

it checks the variable to the next one and swaps them if bigger.
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Zack
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« Reply #2 on: March 28, 2004, 05:05:04 PM »

Wha-? That's a Bubble Sort you're talking about, WT. Quicksort is a lot different, and a lot faster.
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Agamemnus
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« Reply #3 on: March 28, 2004, 05:16:00 PM »

Plus, it's full of spelling errors.

http://forum.qbasicnews.com/viewtopic.php?t=4545&highlight=quicksort
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whitetiger0990
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« Reply #4 on: March 28, 2004, 06:45:12 PM »

Quote from: "Zack"
Wha-? That's a Bubble Sort you're talking about, WT. Quicksort is a lot different, and a lot faster.

 :shifty: *Stab and run*
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Agamemnus
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« Reply #5 on: March 29, 2004, 10:43:01 AM »

Um, you can come back now.

There is quicksort stuff in there.

You'll have to serve some e-time for e-stabbing Zack though. (I believe he has already e-bled to e-death.)
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Moneo
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« Reply #6 on: April 09, 2004, 10:35:47 PM »

Quote from: "david9c"
....Where can I find a text description of the logic for quicksort?

I have two sample programs that sort an array, but I'm
interested in sorting random access files, large files....

When you talk about Quicksort, Bubble Sort, etc., you're talking about internal or memory sorts. The best implementation of Quicksort that I've seen is fully detailed in Ethan Winer's book which you can download free from: www.ethanwiner.com
He's a famous QB expert.

Now, when you talk about sorting files, that's another thing entirely which takes you into the big leagues. Very few programmers have actually gotten into the subject of file sorts. If you really need to do files sorts, and think that you will need this in the future, my recommendation is to spend $149 for the best file sort utility that I have ever seen, from: www.opttech.com
I've been using it for 19 years. It's blazing fast and bullet-proof. The opttech people have been in business for 20 years doing nothing else but sort utilities. Once you have it, you will find many uses for it, including calls to internal or memory sorts. Take a look at their site.
P.S. Writing your own file sort will become a monster project, plus you need to know the theory.
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adosorken
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« Reply #7 on: April 09, 2004, 11:57:49 PM »

I believe he was actually referring to sorting the records inside a random access file, not actually sorting the file order on the disk... Cheesy
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Moneo
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« Reply #8 on: April 10, 2004, 12:31:37 AM »

Right, Adosorken, could be. Let's see what he has to say.
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