How to initialize this NodeList class in C

Question

I'm pretty newbie in C language and I have this little code in which I want to do some test in the main code.

struct ListNode
{
    int val;
    struct ListNode *next;
};

I want to create some examples (For example: 4 -> 9 -> 1) in the main code, but I don't really know how to initialize them. Thank you in advance.

Answer 1

I would do something like this:

struct ListNode* addnode(struct ListNode *head,int val)
{
    struct ListNode* newnode = malloc(sizeof(*this));
    newnode->val = val;
    newnode->next = NULL;
    if (!head) head = newnode;
    else {
        struct ListNode *this = head;
        while(this->next)
            this = this->next;
        this->next = newnode;
    }
    return head;
}

int main(void)
{
    struct ListNode *head = NULL;

    head = addnode(head,4);
    addnode(head,9);
    addnode(head,1);

    return 0;
}