Question

i have this problem: as i can add list to one list? i have tried so, but main list return always one list, and not understand where i mistake.
The structure is this:

  PCombArray = array of Integer;
  PStatsRecord = record
    Comb: PCombArray;
    Freq: Integer;
  end;
  PStatsList = TList<PStatsRecord>;
  TStatsList = TList<PStatsList>;

Where Comb is a field that work as primary key. But here all ok. i define main list as:

var
  MainList: TStatsList;
  MySubList: PStatsList;

and create it, without problem. A procedure work for populate a subList; for esample i call this procedure as MakeSubList and assign a MySubList the list maked, then i add it to main list:

  MainList := TList<PStatsList>.Create;
  try
    MainList.Clear;    
    for index := 1 to N do // generate N subList
    begin  
      ...
      MySubList := MakeSubList(index); // contain correct sub list, no problem here
      ...
      MainList.Add(MySubList);  // add mysublist to mainlist
    end;
    writeln (mainList.count);  // return 1, and not N-1 sublist
  finally
    MainList.Free;
  end; 

Thank who help me to understand so i can solve it. Thanks again.

Answer 1

Your make sub list function might be wrong, or you might have confused yourself with your naming conventions which did not follow in any way the usual Delphi/Pascal naming conventions for types.

The following code works, though.

Note that a TList is an Object so if you want to make a List of TList be sure to use TObjectList instead of plain TList unless you like memory leaks. Your inner list is around a record type and does not need to be TObjectList, but if you changed StatsRecord to TStatsData as a TObject (class) type, you should also change to TObjectList.

unit aUnit5;

interface

uses Generics.Collections;

procedure Test;

implementation

type
      CombArray = array of Integer;
      StatsRecord = record
        Comb: CombArray;
        Freq: Integer;
      end;
      TStatsList2 = TList<StatsRecord>;
      TStatsList = TObjectList<TStatsList2>;

var
      MainList: TStatsList;
      MySubList: TStatsList2;
      index:Integer;

procedure Test;
begin

      MainList := TStatsList.Create;
      try
        for index := 1 to 10 do // generate N subList
        begin
          MySubList := TStatsList2.Create;
          MainList.Add(MySubList);  // add mysublist to mainlist
        end;
        finally
        MainList.Free;
      end;
end;


end.