BorlandTalk.com

Dave Norton · Guest

How to sort a TList? I can't figure out how to write a sort
function that compiles and access fields in TMyType.

type
pTMyType = ^TMyType;
TMyType = class(TObject)
public
fString1 : string;
fString2 : string;
end;

function MySort(Item1, Item2: Pointer): Integer;

fMyTypeList : TList;
..
..
fMyTypeList := TList.Create;
..
..
fMyTypeList.Add(anItem1);
fMyTypeList.Add(anItem2);
..
..
fMyTypeList.Sort(MySort); // or fMyTypeList.Sort(@MySort);
..
..
//______________________________________________________________________
function MySort(Item1, Item2: Pointer): Integer;
var
begin
// What to I write here? I've snipped out most of my attempts.

// This is similar to the example in Delphi help, but doesn't compile:

Result := CompareText((Item1 as TMyType).fString1, (Item2 as
TMyType).fString2);
end;

Here is the example from the Delphi help. The Sort function is _not_
called with the 'CompareNames' function - is this a misprint?

function CompareNames(Item1, Item2: Pointer): Integer;
begin
Result := CompareText((Item1 as TComponent).Name, (Item2 as
TComponent).Name);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
List1.Sort(@CompareText);
end;

Summary: How to write a compare function for TList.Sort?

Thanks much!

Jens Gruschel · Guest