insertion of node

// A complete working C program to demonstrate
// all insertion methods on Linked List

struct Node
{
int data;
struct Node *next;
};


void push(struct Node** head_ref,
		int new_data)
{
	struct Node* new_node =
		(struct Node*) malloc(sizeof(struct Node));

	new_node->data = new_data;

	new_node->next = (*head_ref);

	(*head_ref) = new_node;
}

void insertAfter(struct Node* prev_node,
				int new_data)
{
	
	if (prev_node == NULL)
	{
	printf("the given previous node cannot be NULL");
	return;
	}

	struct Node* new_node =
		(struct Node*) malloc(sizeof(struct Node));

	new_node->data = new_data;

	new_node->next = prev_node->next;

	prev_node->next = new_node;
}

void append(struct Node** head_ref,
			int new_data)
{
	struct Node* new_node =
		(struct Node*) malloc(sizeof(struct Node));

	struct Node *last = *head_ref;

	new_node->data = new_data;

	new_node->next = NULL;

	if (*head_ref == NULL)
	{
	*head_ref = new_node;
	return;
	}

	while (last->next != NULL)
		last = last->next;

	last->next = new_node;
	return;
}

void printList(struct Node *node)
{
while (node != NULL)
{
	printf(" %d ", node->data);
	node = node->next;
}
}

int main()
{
struct Node* head = NULL;

append(&head, 6);

push(&head, 7);

push(&head, 1);

append(&head, 4);

insertAfter(head->next, 8);

printf("Created Linked list is: ");
printList(head);

return 0;
}