Linked list value pointed only changing inside function in C - c

Question

I am trying to implement a linked list in C:
struct Node{
struct Node *next;
void *data;
};
With an insert function:
void insert(void *p2Node, void *data)
{
struct Node *newNode;
struct Node **p2p2Node= (struct Node **)p2Node;
if (newNode = malloc(sizeof(struct Node))) /* if successfully allocated */
{
newNode->data = data;
if ((*p2p2Node) != NULL) /* if the list is not empty */
{
newNode->next = (*p2p2Node)->next;
(*p2p2Node)->next = newNode;
}
else
(*p2p2Node) = newNode;
p2Node = p2p2Node;
}
printf("Inside the insert: %s\n", (*p2p2Node)->data);
}
I called insert in main():
int main()
{
char *setA = "liquid ";
char *setB = " lgd";
char *setC = "sample";
struct Node *nList = malloc(sizeof(struct Node));
insert(nList, setC);
printf("2Get %s\n", nList->data);
return 0;
}
No error or warning was reported, but the value was only changed inside the insert. Back to main() the linked list is still empty.
I do not understand: nList in main() is a void pointer. Inside insert(), *p2Node is not altered, I used p2p2Node to change the value p2Node points to, why is it not working? Did I mismatch the pointers? Is there a way I can make it work without modifying the parameter of insert()?
Thank you.

Answer 1

Use this code to insert values to the linked list.
struct node{
int data;
struct node* link;
};
struct node *root = NULL;
int len;
int main()
{
append();
display();
addatbegin();
display();
addatafter();
display();
}
Add values to the end of the list.
void append(){
struct node* temp;
temp = (struct node*)malloc(sizeof(struct node));
printf("Enter the data: ");
scanf("%d", &temp->data);
temp->link = NULL;
if(root == NULL) //list is empty
{
root=temp;
}else
{
struct node* p;
p=root;
while(p->link != NULL)
{
p = p->link;
}
p->link = temp;
}
}
Add values to the beginning of the list.
void addatbegin()
{
struct node* temp;
temp = (struct node*)malloc(sizeof(struct node));
printf("Enter the data : ");
scanf("%d", &temp->data);
temp->link = NULL;
if(root == NULL)
{
temp = root;
}
else
{
temp->link = root;
root = temp;
}
}
Add value after a node
void addatafter()
{
struct node* temp, *p;
int loc, i=1;
printf("Enter the location : ");
scanf("%d", &loc);
if(loc > len)
{
printf("Invalid input.");
}
else
{
p = root;
while(i > loc)
{
p = p->link;
i++;
}
temp = (struct node*)malloc(sizeof(struct node));
printf("Enter the data : ");
scanf("%d", &temp->data);
temp->link = NULL;
temp->link = p->link;
p->link = temp;
}
}
To display the linked list
void display(){
struct node* temp;
temp = root;
if(temp == NULL)
{
printf("List id empty.\n");
}
else
{
while (temp != NULL){
printf("%d -> ", temp->data);
temp = temp->link;
}
printf("\n\n");
}
}