singly linked list 单向链表反转

以前一直都没写过，今天写了个：

 

/*
 * reserve the linked list without circular 链表反向
 */

 #include <stdio.h>
 #include <stdlib.h>

 struct linklist
 {
   struct linklist *next;

   int key;
 };

 void
 printf_linklist (struct linklist *head)
 {
   struct linklist *lnode;

   if (head == NULL)
     printf ("%% linklist is NULL\n");

   lnode = head;
   printf (" Linklist : ");
   for (; lnode; lnode = lnode->next)
     {
     printf (" %d ", lnode->key);
     }

   return;
 }

 struct linklist *
 reverse_linklist (struct linklist *head)
 {
   struct linklist *re_link;
   struct linklist *link_tmp;
   struct linklist *link_next;

   if (head == NULL)
     return NULL;

   re_link = head;
   link_next = head->next;
   re_link->next = NULL;

   while (link_next)
     {
     link_tmp = link_next;

       link_next = link_next->next;

       link_tmp->next = re_link;
       re_link = link_tmp;
     }

    return re_link;
 }

 struct linklist *
 create_linklist (int numb)
 {
   int i;
   struct linklist *lists[numb];
   struct linklist *lnode;
   struct linklist *lnode_n;

   for (i = 0; i < numb; i++)
     {
     lists[i] = (struct linklist *) malloc (sizeof (struct linklist));
        if (lists[i] == NULL)
         break;

        lists[i]->key = i;
        lists[i]->next = NULL;
        if (i > 0)
         lists[i-1]->next = lists[i];
     }

   if (i < numb)
     {
     for (lnode = lists[0]; lnode; lnode = lnode_n)
     {
         lnode_n = lnode->next;
         free (lnode);
         lnode = NULL;
         }

     return NULL;
     }

   return lists[0];
 }

 void
 destroy_linklist (struct linklist *head)
 {
   struct linklist *lnode;
   struct linklist *lnode_n;

   if (head == NULL)
     return;

   for (lnode = head; lnode; lnode = lnode_n)
     {
     lnode_n = lnode->next;
     free (lnode);
     lnode = NULL;
     }

   return;
 }
 int
 main (void)
 {
   int numb;
   struct linklist *head;

   printf ("\n pls enter the listnode numb : ");
   scanf ("%d", &numb);

   head = create_linklist (numb);
   printf ("\n before reverse :");
   printf_linklist (head);

   head = reverse_linklist (head);
   printf ("\n after reverse :");
   printf_linklist (head);

   destroy_linklist (head);

   return 0;
 }

运行结果：(gcc, 今天利用这个特意试了下gdb 调试)