TList.Capacity Property

List capacity.

Pascal

property Capacity: Integer;

C++

__property int Capacity;

Description

Capacity gets or sets the list capacity, that is, the maximum size of the list without resizing. The capacity cannot be set to less than Count, the actual number of items in the list.

The TrimExcess method reduces the capacity of the list to its current number of elements, Count.

Delphi Examples:

Copy Code

{
This example demonstrates the usage of the generic TList class.
}
procedure TForm3.Button1Click(Sender: TObject);
var
  List: TList<Integer>;
  FoundIndex: Integer;
begin
  { Create a new List }
  List := TList<Integer>.Create();
  { Register a notification call-back }
  List.OnNotify := ListChanged;
  { Add a few values to the list }
  List.AddRange([5, 1, 8, 2, 9, 14, 4, 5, 1]);

  MessageDlg('Index of first 1 is ' + IntToStr(List.IndexOf(1)),
    mtInformation, [mbOK], 0);
  MessageDlg('Index of last 1 is ' + IntToStr(List.LastIndexOf(1)),
    mtInformation, [mbOK], 0);
  MessageDlg('List contains elemnt 100? ' + BoolToStr(List.Contains(100)),
    mtInformation, [mbOK], 0);

  { Add another element to the list }
  List.Add(100);

  MessageDlg('There are ' + IntToStr(List.Count) + ' elements in the list.',
    mtInformation, [mbOK], 0);

  { Remove the first occurence of 1 }
  List.Remove(1);
  { Delete a few elements form position 0 }
  List.Delete(0);
  List.DeleteRange(0, 2);
  { Extract the remeining 1 from the list }
  List.Extract(1);
  { Set the capacity to the actual length }
  List.TrimExcess();
  MessageDlg('There capacity of the list is ' + IntToStr(List.Capacity),
    mtInformation, [mbOK], 0);

  { Clear the list }
  List.Clear();
  { Insert some elements }
  List.Insert(0, 2);
  List.Insert(1, 1);
  List.InsertRange(0, [6, 3, 8, 10, 11]);

  { Sort the list }
  List.Sort();

  { Binary search for the required element }
  if List.BinarySearch(6, FoundIndex) then
    MessageDlg('Found element 6 at index ' + IntToStr(FoundIndex), mtInformation, [mbOK], 0);

  { Reverse the list }
  List.Reverse();
  MessageDlg('The element on position 0 is ' + IntToStr(List.Items[0]), mtInformation, [mbOK], 0);
end;

procedure TForm3.ListChanged(Sender: TObject; const Item: Integer; Action: TCollectionNotification);
begin
  { This method is called by the List everytime a change occurs }
  if Action = cnAdded then
     MessageDlg('Element added: ' + IntToStr(Item), mtInformation, [mbOK], 0)
  else if Action = cnRemoved then
     MessageDlg('Element removed: ' + IntToStr(Item), mtInformation, [mbOK], 0)
  else if Action = cnExtracted then
     MessageDlg('Element extracted: ' + IntToStr(Item), mtInformation, [mbOK], 0)
end;