Circular linked list and bidirectional linked list - practice after class

The first 1 Turn off ： Basic operation of single cycle linked list

Our mission ：
1. Create an empty single cycle linked list ;
2. Realize the incremental and orderly insertion and deletion of the single cycle linked list ;
3. Realize single loop linked list traversal and output node data elements .

#include <stdlib.h>
#include <stdio.h>
struct node
{ 
    // Linked list node type , Contains a for storing integer data  data  member , And a point to the next node next member 
    int data;
    struct node