Create a singly linked list (the way to create a head node, initial assignment of the head insertion method)

// Enter several integers on the keyboard, and create a singly linked list with head nodes in reverse order of input data (header insertion creates a singly linked list) 
#include <stdio.h> 
#include <stdlib.h> 

typedef struct Link { 
    int data; 
    struct Link * next; 
} link; 


// 
InitLink (link * head_node) { 
    head_node = (link *) malloc (sizeof (link)); // Create head node 
    head_node-> data = 0; // The initial assignment value of the head node data field is 0 
    head_node-> next = NULL; 

    link * ptail = head_node; 

    // The header insertion assignment 
    printf ("Enter several values ​​to save in reverse order to the linked list: \ n"); 
    int num = 0; 
    while (num! = -1) {// Enter -1 to end 
        scanf ("% d", & num); 
        link * new_node = (link *) malloc (sizeof (link)); // Apply for a new node 
        new_node-> data = num; // Assign initial value to new node
        new_node-> next = head_node; // The pointer field of the new node is the last node 
        head_node = new_node; // The new node becomes the last node (head node, head node is in the back) 
        ptail = new_node; // tail The pointer points to this new node, keep moving forward 
    } 
    printf ("The value pointed by the tail pointer is:% d \ n", head_node-> next-> data); 
    // return ptail; // will point to the last node The tail pointer returns 
    return head_node; 
} 


// Traversing the linked list (established in reverse order, sequential traversal) 
void showLink (link * head_node) { 
    link * tmp = head_node-> next; // The next node from the head node is the first one The node begins to traverse to avoid outputting the end flag -1 
    while (tmp! = NULL) { 
        // if (tmp-> data == -1) { 
        // break; // Sequential traversal, the end flag -1 is not output. Control, otherwise none will be output 
        // 
        printf ("% d", tmp-> data); 
        tmp = tmp-> next;
    }
}

void main() {
    link * myHeadNode = NULL;
    myHeadNode = initLink (myHeadNode); // Get the initialized head node 
    printf ("The linked list created in reverse order is: \ n"); 
    showLink (myHeadNode); 
}

0 is the value in the head node, you can not print, traverse to tmp-> data == 0 when traversing, just exit the traversal.