// Given a reference (pointer to pointer) to the head
// of a list and an int, push a new node on the front of the list.
// Creates a new node with the int, links the list off the .next of the
// new node, and finally changes the head to point to the new node.

void Push(node** headRef, int newData) {
node* newNode = (node*) malloc(sizeof(node)); // allocate node
newNode->data = newData; // put in the data
newNode->next = (*headRef); // link the old list off the new node
(*headRef) = newNode; // move the head to point to the new node
}


Test Driver:
struct lNode {
int data;
lNode *next;
}

typedef struct lNode node;

// Build and return the list {1, 2, 3}
node* buildList() {
node* head = NULL; // Start with the empty list
Push(&head, 3); // Use Push() to add all the data
Push(&head, 2);
Push(&head, 1);
return(head);
}