inserting in order a linked list

[qubit67]

I have written a funciton : insert_in_order(*list_t, int) that takes a value and inserts it in order into a linked list, although becuse i am new to them, I'm not aure about the validity of this statement:
if (ptr->data<value && ptr->next->data>value) which i used to find the correct position to insert the data. Is it valid?

[quzah]

Well you'll need to check for duplicates, meaning one of those tests won't work:

1 -> 3

Trying to insert 3 here will fail your test.

You also have to consider that ptr->next might be NULL, so you can't just automatically jump to ptr->next->data without checking that first.


Quzah.

[qubit67]

i ammended the code and have thusfar untested :

list_t
*insert_in_order (list_t *list, int value) {
	node_t *new, *ptr;
	new = malloc(sizeof(*new));
	assert(list!=NULL);
	new->data=value;
	ptr=list->head;
	if (ptr->data<value)
/*must be smaller than the head, insert it at the head and stop*/
	{
		list = insert_at_head(list, value);
	}
	while (ptr!=NULL)
	{
		if (ptr->data==value)
/*equal values, so it doesn't matter if it is put in before or after, we'll do it before*/
		{
			new->next=ptr->next;
			ptr->next=new;
			break;
		}
		
		if (ptr->data<value && ptr->next->data>value)
/*must be the right place to insert*/
		{
			new->next=ptr->next;
			ptr->next=new;
			break;
		}
		else 
		{
			ptr = ptr->next;
		}
	}
/*Reached end of the line wihtout a larger value ahead, insert at foot*/
	list = insert_at_foot(list, value);
	return list;
}