RE: Sorting a Multi-occurrence data structure

[Joel Fritz <JFritz@xxxxxxxxxxxxxxxx>]

IIRC, you pass qsort the address of the beginning of the list and the length
of a list element.  The following has a straight forward description of the
algorithm:

http://linux.wku.edu/~lamonml/algor/sort/quick.html

I know it wasn't obvious to me when I took Data Structures in school.  For a
couple of years I had it memorized in Pascal, but it's long gone now.

> -----Original Message-----
> From: Fisher, Don [mailto:Dfisher@roomstoreeast.com]
> Sent: Tuesday, November 12, 2002 11:33 AM
> To: 'rpg400-l@midrange.com'
> Subject: RE: Sorting a Multi-occurrence data structure
>
>
> Yes, I know, but how does QSORT determine which occurrences
> are passed to
> the RPG procedure for comparison?  Does it make any
> assumptions as to the
> position of the sort field?
>
> For example, say I have a data structure containing four
> fields with values
> as follows that I wish to sort by the third field:
> B 1 DD 5
> A 1 AA 6
> D 2 BB 4
> C 3 CC 2
>
> If I use QSORT, it will presumably send the first two
> occurrences back for
> comparison and my procedure will indicate occurrence one
> should come after
> occurrence two.  Would it then present the third occurrence
> for comparison
> with the first two?
>
> I would think so, but I'm not sure based on what I've read.
>
> Donald R. Fisher, III
> Project Manager
> The Roomstore Furniture Company
> (804) 784-7600 extension 2124
> DFisher@roomstoreeast.com
>
> <clip>
> You provide the procedure that qsort uses to compare elements
> in order to
> sort the list.  The procedure you provide can use any element
> in doing the
> comparison.
> <clip>
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