How-to-easily-implement-a-2-dimensional-stringlist-


            Title: How to easily implement a 2-dimensional stringlist !
Question: How to append additional data to a string in a stringlist, listbox, memo or combobox !
Answer:
To add strings in a stringlist is very easy:
var hSL: TStringList;
begin
 hSL:= TStringList.Create;
 hSL.Add('any string...');
 hSL.Destroy;
end;
Howevery - sometimes you need to add additional information
to every string. This can be done by the objects-property:
var hIndex: integer; // any number that specifies the line
begin
 hSL.Add('my string');
 hSL.Sort;
 hIndex:= hSL.IndexOf('my string');
 hSL.Objects[hIndex] := TStringList.Create;
 TStringList(hSL.Objects[hIndex]).Add('any substring...');
end;
The definition of the object property looks like this:
property Objects[Index: Integer]: TObject;
It takes an index where any object (every delphi class derives
from TObject) can be assigned respectively appended.
To get the right index we call the function 'IndexOf'. IndexOf
only works when the stringlist is sorted !
Having the index whe can append a new stringlist:
 hSL.Objects[hIndex] := TStringList.Create;
With a typecast this 'sub-stringlist' can be filled:
 TStringList(hSL.Objects[hIndex]).Add('any substring...');
If you need to parse the sub-stringlist, just do this:
 for i:= 0 to hSL.Count - 1 do
 for ii:= 0 to TStringList(hSL.Objects[i]).Count - 1 do
 Memo1.Lines.Add(TStringList(hSL.Objects[i]).Strings[ii]);
When the application terminates every substringlist has to be
destroyed explicitely:
 for i:= 0 to hSL.Count - 1 do
 hSL.Objects[i].Destroy;
Now you can destroy the main stringlist itself:
 hSL.Destroy;
Of course you can also define your own 'data-container' that
can be appended to every line in the stringlist. Just define
a class:
type
 TSLData = class
 public
 X1: integer;
 x2: string;
 // etc.
 end;
 ...
 hSL.Objects[hIndex] := TSLData.Create;
 TSLData(hSL.Objects[hIndex]).X1 := 123;
 TSLData(hSL.Objects[hIndex]).X2 := '123';
The great thing is that this works in the same way for every VCL
class that uses TStings like:
TMemo
TListbox
TCombobox
etc.
or other classes that provide a Data property, like:
TTreeView
or
TListView
String Delphi
