Author: Tomas Rutkauskas

I created a component TMyCheckListBox which inherited from TCheckListBox, and I 
want to sort the list of items in numeric not alphabetic order. Although I set the 
Sorted property to True, I cannot sort it in the way I want. I need to have a 
numeric sort with the Sorted property set to True.

Answer:

The Sorted property calls the built-in capability of the underlying windows control 
to sort itself alphabetically. In case you need to perform a custom sorting, just 
turn the Sorted property off, and do the sorting by using TStringList CustomSort 
method. Below is the sequence of possible steps

Assign listbox's items to the string list. Perform custom sorting by calling the 
CustomSort method. You should pass a function that compares two strings in the 
string list as parameter (see example below for details). Move items back to the 
listbox. Here's an example. It resorts the list's content in custom order:

1   {This function sorts items in the list}
2   
3   function CompareStrings(List: TStringList; Index1, Index2: Integer): Integer;
4   var
5     XInt1, XInt2: integer;
6   begin
7     try
8       XInt1 := strToInt(List[Index1]);
9       XInt2 := strToInt(List[Index2]);
10    except
11      XInt1 := 0;
12      XInt2 := 0;
13    end;
14    Result: = XInt1 - XInt2;
15  end;
16  
17  procedure TForm1.SpeedButton5Click(Sender: TObject);
18  var
19    XList: TStringList;
20  begin
21    XList := TStringList.Create;
22    CheckListBox1.Items.BeginUpdate;
23    try
24      XList.Assign(CheckListBox1.Items);
25      XList.CustomSort(CompareStrings);
26      CheckListBox1.Items.Assign(XList);
27    finally
28      XList.Free;
29      CheckListBox1.Items.EndUpdate;
30    end;
31  end;