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Problems with TCollection

Posted on 1997-03-18
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Last Modified: 2010-04-04
I'm a new Delphi 2 user and I want rewrite some TPW programs in D2, but I don't know how the TCollection object works in D2.
My code in TPW is
Type
   PData = ^TData
  TData = Array[0..MaxPoint] of Real;
var
  MyCurve : TCollection;
  Data : PData;

begin
   Data:=New(PData);
   MyCurve:=New(PCollection,Init(10,2));
  ....
   MyCurve^.Insert(Data);
  ....
end.

What is the code in Delphi to do the same thing ?
Thank's for your help.

--
Jean-Louis LAVIE
<jean-louis.lavie@esa5017.u-bordeaux2.fr>

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Question by:jllavie
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mheacock earned 50 total points
ID: 1334892
[This is from the TCollections section fo the Delphi help file].
------------------------------------------------------------
The TCollection object is used to maintain a collection of TCollectionItem objects. TCollection maintains an index of the collection items in its Items array. The Count property contains the number of items in the collection. Use the Add and Clear properties to add new items to the collection or to delete items from the collection. Objects descended from TCollection can contain objects descended from TCollectionItem. Examples are in the TStatusBar and THeaderControl controls which use TStatusPanels and THeaderSections collection objects to contain TStatusPanel and THeaderSection collection items.

In addition to these properties, methods, and events, the TCollection object also has the methods that apply to all objects and is a direct descendent of TPersistent.
--------------------------------------------------------------

Just by looking at your code, it looks to me that a TList might better serve your purposes.  A TList keeps a list of pointers.  Since you want to store Reals (btw, the Real type is slowly being phased out and is incompatible with other programming languages, use Single, which is byte compatible with C/C++'s Float), the Tlist would store pointers to those real objects.

If you replace TList with TCollection in your code, the changes are very simple.

var
    MyCurve: TList;
    ...
begin
    ...
    MyCurve := TList.Create;
    ...
    MyCurve.Add(Data);
    ...
    Data := TData(MyCurve.Items[n]);
end;
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