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06.03.2008 at 12:37AM PDT, ID: 23452279
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9.4

Deallocate a pointer without deleting it.

Asked by Snapples in Microsoft Visual C++.Net, C++ Programming Language, Microsoft Visual C++

Tags:

I'm working on a non-MFC VC++ project and this is the problem.
I have 2 screens, a menu screen and an options screen, both are pointers. They use a lot of bitmaps and a lot of memory and it's possible to switch between the 2. So when the user switches, I want the current one to be deleted to save memory. Ofcourse, when I use delete on one of those pointers, I can't create a new one later.

Right now, I'm calling the destructor of that screen, to delete all bitmaps used in that class and set the pointer to NULL. This works fine but it still leaves me with a memory leak, 84 bytes, because it allocates new memory space when I create a new instance of that pointer.

So, the way I see it I'd either need some way to free the pointer from memory but not delete it so I can still use it later. Or when I create a new instance of that pointer, make it that it uses the same memory space as the first time. But I don't have a clue on how to do that.

I've attached some code, hopefully that'll make it more clear what I mean. Also, the lines I commented don't see to do anything at all.

Thanks in advance.

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switch (OPTIONS->GetCurrentScreen())
        {
        // Current Screen = 1 --> Main menu.
        case 1:
            if (mainmenu != NULL)
            {
                ShowTitlescreen();
            }
            else
            {
                StartTitlescreen();
                ShowTitlescreen();
                StopOptions();
            }
            break;
        // Current Screen = 2 --> Options.
        case 2:
            if (options!= NULL)
            {
                ShowOptions();
            }
            else
            {
                StartOptions();
                ShowOptions();
                StopTitlescreen();
 
            }
            break;
        }
 
 
//-------------------------------------
 
 
void Main::StartTitlescreen()
{
    //if (mainmenu == NULL)
        //delete mainmenu;
    mainmenu = new Menu();
}
 
void Main::ShowTitlescreen()
{
    mainmenu->Tick();
    mainmenu->Paint();
}
    
void Main::StopTitlescreen()
{
    if (mainmenu != NULL)
        mainmenu->~Menu();
    mainmenu = NULL;
}
 
void Main::StartOptions()
{
    //if (options == NULL)
        //delete options;
    options = new Options(options->MODE);
}
 
void Main::ShowOptions()
{
    options->Tick();
    options->Paint();
 
}
 
void Main::StopOptions()
{
    if (options != NULL)
        options->~Options();
    options = NULL;
}
[+][-]06.03.2008 at 12:50AM PDT, ID: 21698290

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About this solution

Zones: Microsoft Visual C++.Net, C++ Programming Language, Microsoft Visual C++
Tags: Visual C++
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Solution Provided By: evilrix
Participating Experts: 2
Solution Grade: A
 
 
[+][-]06.03.2008 at 12:52AM PDT, ID: 21698297

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[+][-]06.03.2008 at 12:54AM PDT, ID: 21698307

At Experts Exchange, members can ask their questions to thousands of technology professionals, also known as Experts. Experts compete and collaborate to answer those questions by leaving comments like this one.

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