Segmentation Error with a linked list while loop - c

Question

I am having trouble with a project I am working on for class. I am particularly having trouble with recursively printing a linked list of spheres. Whenever the program runs over the particular part:
ss=ss->next;
there is a Segmentation fault: 11. What could the problem be?
(Note: I've included the necessary structssphereandsphere_list, and left outrgbandvec` so as to not clutter up the code.)
typedef struct sphere {
vec *center;
double radius;
rgb *color;
} sphere;
typedef struct sphere_list sphere_list;
/* convention: NULL is the empty sphere list */
struct sphere_list {
sphere *s;
sphere_list *next;
};
void sl_print(sphere_list *ss)
{
if(ss==NULL)
printf("SPHERE LIST EMPTY\n");
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
printf("SPHERE LIST:\n");
int i=1;
while(ss->s!=NULL){
printf("\t%d ", i);
sphere_print(ss->s);
if(ss->next==NULL){
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
return;
}
ss=ss->next;
i++;
}
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
return;
}

Answer 1

try this:
void sl_print(sphere_list *ss)
{
if(ss==NULL){
printf("SPHERE LIST EMPTY\n");
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
printf("SPHERE LIST:\n");
return ;
}
int i=1;
while(ss != NULL){
printf("\t%d ", i);
sphere_print(ss->s);
ss=ss->next;
i++;
}
}

Answer 2

struct sphere_list {
sphere *s;
sphere_list *next;
};
have you allocated space for sphere *s and made the pointer point to valid memory?, I would have done this, just a suggestion.
typedef struct sphere {
vec *center;
double radius;
rgb *color;
//included the pointer in the struct//
struct sphere *next
} sphere;
Also, typedef structs are not favoured by most people.makes the code harder to read.

Answer 3

You made an error in your loop conditions. You have to test next value, because this is why you move on on sphere_list.
void sl_print(sphere_list *ss)
{
sphere_list *tmp = ss;
if(ss==NULL)
printf("SPHERE LIST EMPTY\n");
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
printf("SPHERE LIST:\n");
int i=1;
while(tmp!=NULL){
printf("\t%d ", i);
if (tmp->s != NULL)
sphere_print(tmp->s);
if(tmp->next==NULL){
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
return;
}
tmp=tmp->next;
i++;
}
printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
return;
}
Modified*