🚀 go-pugleaf

Dan Mayo wrote:
> I have created some test code that dynamically creates a form; on that 
> form is a button and a string grid.  The button click event fills in a 
> number of static objects with random data; then prior to exiting the 
> function posts all that data into the StringGrid; this should in effect 
> clean up those objects when the click even expires leaving just the data 
> in the grid.  That much works.
> 
> However, when I close the form, when is then followed by a delete 
> operator, the memory doesn't appear to be freed (looking at the Virtual 
> Size of the program via the task manager).
> 
> Reading the TStringGrid help, it looks as though I need to delete the 
> 'objects' in the stringgrid too?  How?  Is there something else I am 
> missing?
> 
> I'm still trying to track down the problem I am having where I can't 
> create a new TForm at random times that I posted in "Creating new TForm 
> causes 'Out of Resources' error on WinXP" a few weeks ago.  It's not 
> that my program is taking up much memory, or the leak I see in the above 
> test app is that big.  I'm grasping at straws to find out what is going 
> on here; any help would be appreciated.
> 
> Thanks.
> 
> 

The example code is as follows: (Note, MainForm, Form1's button1 event 
contains a loop that dynamically creates a Form2 which is then deleted 
after the modal operation is done; Form2 kicks off a timer when shown, 
and the timer event does some processing, then returns a modal result; 
Where is the memory leak?  Of course the code operates faster when the 
length of the dynamic array is defined before the first loop; the leak 
is more pronounced (around 2k per pass) with the code as is; with the 
length predefined, the leak appears to be around 2k per 10000 open and 
closes.

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "MainForm.h"
#include "SubForm.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
         : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
TForm2 *NewForm = new TForm2(this);
NewForm->ShowModal();
delete NewForm;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender)
{
   for (int i=0; i<ScrollBar1->Position; i++)
   {
      Button1->Click();
      StatusBar1->SimpleText = i;
      Application->ProcessMessages();
   }
}
//---------------------------------------------------------------------------
void __fastcall TForm1::ScrollBar1Change(TObject *Sender)
{
Label1->Caption = ScrollBar1->Position;
}
//---------------------------------------------------------------------------


//SUBFORM

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "SubForm.h"
#include <math.h>
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm2 *Form2;
//---------------------------------------------------------------------------
__fastcall TForm2::TForm2(TComponent* Owner)
         : TForm(Owner)
{
    StringGrid1->ColCount = 0;
    StringGrid1->RowCount = 0;
}
//---------------------------------------------------------------------------
void TForm2::DoTest()
{

    StringGrid1->ColCount = 100;
    StringGrid1->RowCount = 100;
    DynamicArray<double> vs;
    for (int i =0; i<100; i++)
    {
      for (int j=0; j<100; j++)
      {
         vs.Length++;
         vs[i+j] = rand();
      }
    }
    for (int i =0; i<100; i++)
    {
      for (int j=0; j<100; j++)
      {
        StringGrid1->Cells[i][j]=vs[i+j];
      }
    }
    ModalResult = mrOk;
}
//---------------------------------------------------------------------------
void __fastcall TForm2::Timer1Timer(TObject *Sender)
{
   Timer1->Enabled = false;
   DoTest();

}
//---------------------------------------------------------------------------