Re: [igraph] igraph_neighborhood and igraph_free

[Tamas Nepusz]

Hi Peter,

> Basically, the vectors pointed to by the vector filled by 
> igraph_neighbourhood need to be passed to igraph_free, but igraph_free 
> isn't part of the API (and is only mentioned once in the manual for a 
> different function).
igraph_free(ptr) is essentially equivalent to the following code
snippet:

free(ptr);
ptr = NULL;

This prevents one from dereferencing a pointer later to a memory area
that has been freed already. So, you are safe to use free(ptr) on the
vectors pointed to by the vector_ptr filled by igraph_neighborhood.

Also, there is igraph_vector_ptr_free_all(v), which calls igraph_free on
all elements of the vector_ptr -- it seems that this function was
accidentally left out of the reference manual, but it is exposed in the
header file, so feel free to use it. There's also
igraph_vector_ptr_destroy_all(v), which is equivalent to
igraph_vector_ptr_free_all(v) followed by igraph_vector_ptr_destroy(v).

-- 
Tamas