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Problems with deallocating void**

Started by gcsaba2 Apr 9, 2005 at 1:20 PM 3 replies 1k views

Original Post

Apr 9, 2005 at 1:20 PM

Hi, I have a code like this:

void** Data = new (void*)[1];
Data[0] = create_bitmap(400,400);

Then I do random stuff with this bitmap, it works fine, for example if I want to draw it then I just write

draw_sprite(Buffer,(BITMAP*)Data[0],100,100);

At the end of the game, I want to deallocate this whole thing. I do it like this:

destroy_bitmap((BITMAP*)Data[0]);   <-- error occurs here
delete[] Data;

So why does it crash when I use delete_bitmap()? Any ideas? Please no replies like "don't use void**" ;)

Drew_Benton

FOUNDER

411

Drew_Benton

Apr 9, 2005 at 1:46 PM

Don't use void** [grin] Ok you using void** is fine, look what I did [smile], but not in the manner you have it. First of all, void* is an unknown size, so the line: void** Data = new (void*)[1]; allocates only 4 bytes of memory for it is a pointer to 'unknown'. That's your main problem. So what you need to do instaed is something like this:

void** Data = new (BITMAP)[1];
// void** Data = new (BITMAP*)[1]; ?? I'm not sure
Data[0] = create_bitmap(400,400);

Now that *should* work. If not please let us know, there is probabally some syntax error somewhere where I posted.

- Drew

gcsaba2

Author

gcsaba2

Apr 9, 2005 at 7:18 PM

Wow you COMPLICATE STUFF even more than I do [grin]. In the end I figured out the same thing you said, and decided it's not worth it. Sure I'd save memory space, but writing stuff like (*(int*)Data[4]) = 5; is just not the thing I'd like to write for a long time. I created several separate arrays for int, BITMAP and other types, it all works ok, only it takes up more space and the code is longer... [sad]

PnP Bios

114

PnP Bios

Apr 9, 2005 at 8:48 PM

for the love of all that is holy, avoid using double pointers. No element of game development, outside of tool development, should involve double pointers.

Drew_Benton

FOUNDER

411

Drew_Benton

Apr 9, 2005 at 9:01 PM

Good decision [smile] I think void* is pushing it, but two levels of direction, as PnP Bios has said, is really useless in games.

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