I have been a sysadmin most of my life, but recently decided to practice some my dev knowledge and attempt a devops position. I have as such been practicing some C and Python skills and wrote some code for inserting a number into a linked list.
void list_insert(struct list *h, int d)
{
struct list *elem = malloc(sizeof(struct list));
elem->data = d;
elem->next = NULL;
if (!h) {
h = elem;
} else {
elem->next = h;
h = elem;
}
}
I noticed that this function doesn't seem to alter the outside view of the variable h (i.e whatever is passed to list_insert) and I noticed that printing at the end of the insert function seems to work. So having tried to look for answers online, I couldn't find anything, obvious but I found most list implementations would have double-pointers. I changed my function to use double-pointers and then it suddenly started working. Could someone help me understand what's happening here as I know pointer management is an important concept and I think I understand what a pointer is and how it relates to memory, but I don't think I get why a single pointer does not get changed, whereas a double-pointer does.
Thanks!