TList.Items Property

Lists the object references.

Pascal

property Items [Index: Integer]: Pointer;

C++

__property void * Items[int Index];

Description

Use Items to obtain a pointer to a specific object in the array. The Index parameter indicates the index of the object, where 0 is the index of the first object, 1 is the index of the second object, and so on. Set Items to change the reference at a specific location.

Use Items with the Count property to iterate through all of the objects in the list.

Not all of the entries in the Items array need to contain references to objects. Some of the entries may be nil (Delphi) or NULL (C++) pointers. To remove the nil (Delphi) or NULL (C++) pointers and reduce the size of the Items array to the number of objects, call the Pack method.

Note: Items is the default property for TList. This means you can omit the property name. Thus, instead of MyList.Items[i], you can write MyList[i].

C++ Examples:

Copy Code

/*
This example creates a list object and inserts two records
into it. The value of the record fields are written on a
paintbox:
*/

#include <memory>       //for STL auto_ptr class

typedef struct AList
{
  int I;
  char C;
} TAList;

typedef TAList* PAList;

void __fastcall TForm1::Button1Click(TObject *Sender)
{
  std::auto_ptr<TList> MyList(new TList);
  // fill the TList
  std::auto_ptr<TAList> AStruct1(new TAList);
  AStruct1->I = 100;
  AStruct1->C = 'Z';
  MyList->Add(AStruct1.get());
  std::auto_ptr<TAList> AStruct2(new TAList);
  AStruct2->I = 200;
  AStruct2->C = 'X';
  MyList->Add(AStruct2.get());
  
  // Go through the list, writing the elements to the
  // canvas of a paintbox component.
  int Y = 10; // position on canvas
  for (int i = 0; i < MyList->Count; i++)
  {
    TAList *AStruct = (PAList) MyList->Items[i];
    PaintBox1->Canvas->TextOut(10, Y, IntToStr(AStruct->I));
    Y += 30;  // Increment Y Value again
    PaintBox1->Canvas->TextOut(10, Y, AStruct->C);
    Y += 30;  //Increment Y Value
  }
}

Delphi Examples:

Copy Code

{
This example creates a list object and inserts two records
into it. The value of the record fields are written on a
paintbox:
} 
procedure TForm1.Button1Click(Sender: TObject);
type
  PMyList = ^AList;
  AList = record
    I: Integer;
    C: Char;
  end;
var
  MyList: TList;
  ARecord: PMyList;
  B: Byte;
  Y: Word;
begin
  MyList := TList.Create;
  try
    New(ARecord);
    ARecord^.I := 100;
    ARecord^.C := 'Z';
    MyList.Add(ARecord); {Add integer 100 and character Z to list}
    New(ARecord);
    ARecord^.I := 200;
    ARecord^.C := 'X';
    MyList.Add(ARecord); {Add integer 200 and character X to list}

    { Now paint the items onto the paintbox}
    Y := 10;             {Variable used in TextOut function}
    for B := 0 to (MyList.Count - 1) do
    begin
      ARecord := MyList.Items[B];
      Canvas.TextOut(10, Y, IntToStr(ARecord^.I)); {Display I}
      Y := Y + 30;  {Increment Y Value again}
      Canvas.TextOut(10, Y, ARecord^.C);  {Display C}
      Y := Y + 30;  {Increment Y Value}
    end;

    { Cleanup: must free the list items as well as the list }
   for B := 0 to (MyList.Count - 1) do
   begin
     ARecord := MyList.Items[B];
     Dispose(ARecord);
   end;
  finally
    MyList.Free;
  end;
end;