Hi Edward,

Consider a double pointer like a matrix (in algebra) witch one you don't
know its dimension a priori.

An example: put the case that we are developing an application witch
calculates the inverse of a matrix of dimensions NxM. The values of N
and M will be determinated by the user and they are unknown a priori. If
so, we declare a doble pointer:

float **ptr;

The application asks to the user the values of of the number of files
(N) and columns (M), and according to them it reserves the "necessary
and sufficient" memory:

ptr = (float**) malloc(files* sizeof(float*);

       for (i=0; i<files; i++)

           ptr[i] = (float*) malloc(columns*sizeof(float));

Once the application has calculated the resulting inverse matrix MxN, we
must delete the memory *manually*.

Aitor.


On 11/09/15 10:35, Edward Bartolo <edbarx@???> wrote:
> Hi all,
>
> Since yesterday I have been trying to understand why "char**
> essid_list" is working inside getInstalledEssidList(&count,
> essid_list) but failing as soon as I try to access essid_list[0]
> outside the function.
>
> Both the source and the gdb text output are attached.
>
> Any helpful pointers are appreciated.