数据结构之单链表循环

单链表循环代码如下：

#include<stdio.h>

#include<stdlib.h>


typedef struct node
{
   int data;
  struct node  *next;

}sqlist;

sqlist *init(void)  //初始化
{
    sqlist *l=NULL;
    l=(sqlist *)malloc(sizeof(sqlist));
    l->data=0;
    l->next=l;

    return l;
}
void  head_insert(sqlist *l,int data) //链表头插法
{
      sqlist *node=(sqlist *)malloc(sizeof(sqlist));
      node->data=data;
      node->next=l->next;
      l->next=node;
      l->data++;
}
void print(sqlist *l) //链表打印
{
   sqlist *p=NULL;
   p=l->next;
   while(p!=l)
   {
      printf("%d->",p->data);
      p=p->next;

  }
   printf("NULL\n");

}

void nail_insert(sqlist *l,int data)//链表尾插法
{
   sqlist *p=l;
   sqlist *node=NULL;
   node=(sqlist *)malloc(sizeof(sqlist));
   node->data=data;
   while(p->next !=l)
    {
       p=p->next;
   }
      node->next=l;
      p->next=node;
}
int delet(sqlist *l,int data) //链表删除
{
    sqlist *pre=l;
  //  sqlist *p=l->next;
    sqlist *node= l->next;
     while(node != l)
      {
         if(node->data==data)
          {
             pre->next=node->next;
             free(node);
             return 1;
          }
          pre=node;
          node=node->next;

      }
    return 0;
}

int  main()   //主函数
{
   sqlist *l=NULL;
   l=(sqlist *)malloc(sizeof(sqlist));
   l=init();
   head_insert(l,1);
   head_insert(l,2);
   head_insert(l,3);
   head_insert(l,4);
   nail_insert(l,6);
   nail_insert(l,8);
   print(l);

   delet(l,2);
   print(l);
   free(l);
   return 0;
}