C语言如何计算链表长度

 #include<stdio.h>

    
 #include<stdlib.h>
    
 #include<time.h>
    
  
    
 struct node
    
 {
    
     int num;
    
  
    
     struct node * next;
    
 };
    
 typedef struct node Node; //重命名
    
 typedef Node * Link;
    
  
    
 enum result_val{RET_OK = 1,RET_NO=0}; //枚举
    
  
    
 void create_head(Link * head)
    
 {
    
     *head = NULL;
    
 }
    
  
    
 int create_node(Link * new_node)
    
 {
    
     *new_node = (Link)malloc(sizeof(Node));
    
  
    
     if(*new_node == NULL)
    
     {
    
     return RET_NO;
    
     }
    
     else
    
     {