1.new=(struct list_head*)malloc(sizeof(struct list_head*));

   if(new==NULL)

    {
       printf("失败\n");

          return;

    }

new->next=prev->next;

prev->next=new;

      return;

2.struct list_head* p=prev->next;

   prev->next=p->next;

   p->next->prev=prev;

   free(temp);

   temp=NULL;

     return;

3. struct list_head* temp = (struct list_head*)malloc(sizeof(struct list_head*));

   if(temp==NULL)

    {
       printf("结点申请失败，插入失败\n");

          return;

    }

      struct list_head* p=head;

      while(p->next!=NULL)

     {
         p=p->next;

     }

          temp->next=NULL;

          p->next=temp;

          temp->prev=p;

          return;

4. entry->next->prev=entry->prev;

entry->prev->next=entry->next;

free(entry);

  entry=NULL;

return;

5. if(head->next==NULL)

    {
         printf("链表为空\n");

     }

       return;