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Tutorial, Course, or Book on ARRAY Handling?
Message
De
09/04/2015 15:23:49
Lutz Scheffler
Lutz Scheffler Software Ingenieurbüro
Dresden, Allemagne
 
 
À
09/04/2015 15:12:03
Information générale
Forum:
Visual FoxPro
Catégorie:
Visual FoxPro Documentation de produit
Versions des environnements
Visual FoxPro:
VFP 9 SP2
OS:
Windows Server 2012
Network:
Windows 2008 Server
Database:
Visual FoxPro
Application:
Web
Divers
Thread ID:
01618082
Message ID:
01618096
Vues:
49
>>>>Does anyone know of a book, course, or tutorial that will teach me how to handle deeper concepts of array handling, something beyond the regular 2-dimensional arrays? My client has one set of arrays that are nested to 10 levels deep. I know that someone on here will say, "Oh, that's a piece of cake (or easy)! An array is just an array."
>>>
>>>Can you give us an idea of what it's used for, and what you need to do? Is it used in support of something like a treeview? Or is there advanced math being used e.g. matrix operations?
>>>
>>>I don't know how much of this you already know but it may be useful for others:
>>>
>>>If you're working in VFP you have DIMENSION to create arrays, then you have to know the syntax for addressing array elements. VFP arrays are one-based (as opposed to many other languages where they are zero-based).
>>>
>>>There are various primitive functions available e.g.
>>>
>>>ACOPY()
>>>ADEL()
>>>AELEMENT()
>>>AINS()
>>>ASORT()
>>>ASUBSCRIPT()
>>>
>>>VFP supports only 1- or 2-dimensional arrays. By "nesting" I suspect you've got a situation where the elements of a given array are themselves arrays, and so forth down as deep as 10 levels.
>>>
>>>If there's existing code, hopefully it includes some more advanced user-defined functions that let you do things like traverse the links/nesting levels. Code like that is often recursive (or it should be) which tends to be tricky and requires great care in maintaining or enhancing.
>>>
>>>As a side note, if you're working with something like a treeview, rather than using nested arrays you can use a single data table (i.e. DBF) and implement a linked list. Processing usually requires writing your own (usually recursive) UDFs. However, depending on what you want to do there may be the option to use dBASE-style ISAM processing (SCAN, GOTO, SKIP etc.) or even the SQL engine. If you're familiar with Fox you may find this approach more intuitive than using arrays.
>>
>>I use collections for n-dimensional stuff.
>
>Yes, that's another valid approach. I haven't had occasion to go that way but it would probably be very useful if nodes are radically different from one another.
>
>If node attributes are similar I really like the table/linked list approach. Great for reporting:
>
>SELECT Various, Node, Columns FROM LinkedList WHERE ...

The thing I do not see in the table is how to adress n dimensions. Or do you create something hierachical like root to colum to row to stack to time to whatever? But this is a pain to retrieve.

Not that a collection is easier, but it could be crosslinked much easier, because there is no real restriction in the number of links to create.
Words are given to man to enable him to conceal his true feelings.
Charles Maurice de Talleyrand-Périgord

Weeks of programming can save you hours of planning.

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