[SOLVED] freeing structure lists

errigour · 07-01-2016, 01:10 PM

say I have a list of structures:

Code:

struct buffer
{
  char *buffer;
  struct buffer *next;
}

Ok I malloced a bunch of structures that link to each other making sure next is null if there aren't anymore commands in the buffer. Can I free iter and still access what iter->next was pointing to if it was malloced data?

Code:

void free_d_buffer_q(struct buffer *q)
{
    struct buffer *iter;
    
    iter = q;
    
    while(iter !=0)
    {
        if( iter->buffer )
          free(iter->buffer);
        q = iter->next;
        free(iter);
        iter = q;
    }
}

ntubski · 07-01-2016, 01:58 PM

Quote:

Originally Posted by errigour

Ok I malloced a bunch of structures that link to each other making sure next is null if there aren't anymore commands in the buffer. Can I free iter and still access what iter->next was pointing to if it was malloced data?

Yes. You can access the data as long as it's not freed.

errigour · 07-01-2016, 03:19 PM

thanks.

jpollard · 07-05-2016, 07:01 AM

Minor addendum - I suggest setting the structure pointers to NULL after releasing what they point to.

This only helps if the structure gets reallocated with malloc, and just happens to give you a structure with existing pointers that are invalid... (which is one reason I use calloc rather than malloc as a habit).