basic questions about Linkedlist and Node Insertion - c

Question

I have some problems about my sub-major lecture.
First of all, sorry for poor English.
anyway, Professor told me that It was very east to solve, just change some lines and it would be work.
but I can't finish this code ontime.
when I play? debug? my code, couldn't print 'List'.
How to print properly about my LinkedList code?
+ I have to fix few lines. not entire code.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct ListNode {
int data;
struct ListNode* link;
}listNode;
void insertFirstListNode(listNode* num, int data) {
listNode* newNode = malloc(sizeof(listNode));
newNode->link = num->link;
newNode->data = data;
num->link = newNode;
}
typedef struct {
listNode* head;
} linkedList_h;
linkedList_h* createLinkedList_h() {
linkedList_h* Newlist = (linkedList_h*)malloc(sizeof(linkedList_h));
Newlist->head = NULL;
return Newlist;
}
void printList(linkedList_h* L) {
listNode* p;
printf("L = (");
p = L->head;
while (p != NULL) {
printf("%d", p->data);
p = p->link;
if (p != NULL) printf(", ");
}
printf(") \n");
}
void main() {
linkedList_h* m;
m = createLinkedList_h();
insertFirstListNode(m, 10);
printList(m);
}

Answer 1

As per my understanding you are trying to add the node to the beginning of the linked list. In that case the below fix should be working fine.
Please have error handling in all the functions like NULL inputs, Malloc fails etc ...
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct ListNode {
int data;
struct ListNode* link;
}listNode;
typedef struct {
listNode* head;
} linkedList_h;
void insertFirstListNode(linkedList_h* num, int data) {
listNode* newNode = (listNode *)malloc(sizeof(listNode));
newNode->link = num->head;
newNode->data = data;
num->head = newNode;
}
linkedList_h* createLinkedList_h() {
linkedList_h* Newlist = (linkedList_h*)malloc(sizeof(linkedList_h));
Newlist->head = NULL;
return Newlist;
}
void printList(linkedList_h* L) {
listNode* p;
printf("L = (");
p = L->head;
while (p != NULL) {
printf("%d", p->data);
p = p->link;
if (p != NULL) printf(", ");
}
printf(") \n");
}
int main() {
linkedList_h* m;
m = createLinkedList_h();
insertFirstListNode(m, 10);
printList(m);
return 0;
}