[SDL] dynamic memory allocation and SDL_Surfaces

[Lilith Calbridge]

Dunno if I can wrap my head around what all you're doing.  You say you
have an array of SDL_Surfaces.  Are you talking about actual surfaces,
which are structures which themselves hold pointers to allocated spaces?
 Or is the first array an array of pointers to SDL_Surfaces?

Lilith

>>> On 9/5/2007 at 3:29 PM, Chris Dickinson <cdickins at udel.edu> wrote:
> I have a question about freeing pointers to surfaces - I'm trying to
figure 
> out whether my program might have a memory leak.  In one function, I
use 
> malloc
> () to create a pointer to an array of SDL_Surfaces. I then load
various 
> images 
> onto the surfaces and pass a pointer to the array to a second
function.  In 
> the second function, I use malloc() to create a second array of
pointers to 
> SDL_Surfaces, and I use this array to access the surfaces passed to
the 
> function (I know that on the surface this sounds odd, but within the
program 
> 
> there is a good reason for doing this).  After the called function
returns, 
> I 
> free each of the surfaces in the array [i.e., for (i=0; i<nSurfaces;
i++) 
> SDL_FreeSurface(surface1[i])] and then free the pointer
[free(surface1)].  
> If 
> I do this, but don't attempt to free the pointers created in the
second 
> function, the program works as it should, and I don't see any obvious

> evidence 
> of memory leaks.  If in the function that is called I try to free the

> pointers 
> to the individual surfaces that were allocated with the call to
malloc() 
> [i.e., for (i=0; i<nSurfaces; i++) SDL_FreeSurface(surface2[i])], I
get a seg 
> 
> fault (which is expected).  If, however, I simply free the pointer
[i.e., 
> free
> (surface2)], I don't get a seg fault.  My question is whether I need
to free 
> 
> the pointer of SDL_Surfaces allocated in the called function or not
(and if 
> not freeing it will result in a memory leak).  I know that if I were
passing 
> a 
> pointer to a single surface and then accessing it with another
pointer, 
> freeing both would cause a seg fault (only the pointer to the
original 
> surface 
> should be freed - the one that was passed).  If anyone has any
thoughts, they 
> 
> would be greatly appreciated.  If it matters, I'm coding in C (MS C++
6.0 
> Professional).  Thanks.
> 
> Regards,
> 
> Chris Dickinson, PhD
> Department of Psychology
> University of Delaware
> 
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