Re[2]: Based variables

["Eric N. Wilson" <doulos1@xxxxxxxx>]

Hello Mark,

Friday, December 08, 2000, 9:33:11 AM, you wrote:

<Snip>

> Another technique in the RPG Programmer's guide is to create a Linked List.
> The problem with this is that it requires at least 2 pointers per record,
> and possibly 3, and creates a lot of pointer management issues.  The above
> technique requires only 1 pointer for the data, and an additional pointer
> for the Based Data Structure.

A Singly Linked List requires only 1 pointer. The pointer to the Next
record (or some magic value to mean the end of the road, usually
*NULL).

A Doubly Linked List requires 2 pointers. A pointer to the Next Record
and a pointer to the first record.

A Binary Tree requires 3 pointers. A pointer to the parent, a pointer
to the right child, and a pointer to the left child.

And if you do not want the actual list to contain the data then add a
pointer to your data in there.

Then there are all sorts of other tree and hash and dictionary
structures which I will point the interested parties to Donald Knuth's
"The Art of Computer Programming" "Fundamental Algorithms" which is
Volume one in the 3 (soon to be 4) volume set. This is my personal
favorite set of books on programming :-)

Once you have the code to manage a linked list, etc... written you can
reuse it over and over and never have to write it again.


----------------------------------
Eric N. Wilson
President
Doulos Software and Computer Services


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