segmentation fault while assigning structure members in c

Question

Hi,

I have two structure in c

struct data{
  char *name;
};

struct lst{
   struct lst *next;
   struct table *data;
};

when I'm trying to assign a name like

l->data->name = d->name; printf("%s",l->data->name);

it gives segmentation fault. So is it because read-only memory or caused by another reason ?

ok I solved the problem : ) I've done :

l->data = d; d has the name already :) thanks all

Answer 1

Just before you do that segmentation-violation-causing instruction, insert:

printf( "%p\n", l);
printf( "%p\n", l->data);
printf( "%p\n", d);
printf( "%p\n", d->name);

and see which one is set to NULL (or an invalid value).

Your segmentation violation is almost certainly caused by an uninitialized pointer.

Answer 2

I can be caused by a member pointing into an invalid zone.

Answer 3

l->data is most likely NULL