C语言双向链表

原文:C语言双向链表

　　今天写了点双向链表的各种操作，写插入的时候费了点时间，不过，现在看来还是值得耗费那点时间去写的，这种小东西应该能信手拈来才行啊。

 /*双向链表*/
 #include <stdio.h>
 #include <string.h>    /*strcmp(const char *,const char *) return 0 is equal*/

  typedef struct dulnode
  {
     char name[];
     struct dulnode *prior,*next;
  }stud;
  /*创建,返回链表头指针，参数n-节点个数*/
  stud * create(n);
  /*查找,返回节点地址，参数h-链表头指针，name为查询条件*/
  stud * search(stud *h,char *name);
  /*删除*/
  void del(stud *p);
  /*显示,参数-h,链表头节点，num-显示节点个数*/
  void show(stud *h,int num);
  /*求链表长度*/
  int length(stud *head);
  /*插入节点,参数head-链表头节点,name-节点，n-节点位置*/
  stud *insert(stud *head,char *name,int n);
  int main()
  {
     stud *head,*re,*in;
     head = create();
     show(head,);
     re = search(head,"Accipiter");
     show(re,);
     del(re);
     re = head->next;
     show(re ,);
     in = insert(re , "cnblogs",);
     show(in,);
     return ;
  }
  void show(stud *head,int num)
  {
     stud *sp;
     int cnt = ;
     if(NULL == head)
     {
         printf("It's NULL!\n");
         return;
     }
     if(num>length(head))
      {
         printf("It's Full\n");
         return ;
     }
     if(strcmp(head->name,"") == )
     {
         sp = head->next;
     }
     else
     {
         sp = head;
     }
     while(sp)
     {
         printf("name %d:%s\n",cnt,sp->name);
         if(cnt == num)
         {
             sp = NULL;
         }else
         {
             sp = sp->next;
             cnt++;
         }
     }
  }

 stud * create(n)
 {
     stud *p,*h,*s;/*p-前指针，h-头指针，s-后指针*/
     int i;
     /*构建头指针*/
     h = (stud *)malloc(sizeof(stud));
     if(h == NULL)
     {
         return NULL;
     }
     h->name[] = '\0';
     h->prior = NULL;
     h->next = NULL;
     /*插入节点*/
     p = h;
     for(i=;i<n;i++)
     {
         s = (stud *)malloc(sizeof(stud));
         if(NULL == s)
         {
             printf("node malloc error!\n");
             break;
         }
         p->next = s;
         printf("%d's name:\n",i+);
         gets(s->name);
         s->prior = p;
         s->next = NULL;/*末尾插入*/
         p = s;
     }
     p->next = NULL;
     return (h);
 }

 stud * search(stud *head , char *name)
 {
     stud *p,*re=NULL;
     p=head->next;
     while(p)
     {
         if(strcmp(p->name,name) == )
         {
             re = p;
             p = NULL;
         }
         else
         {
             p = p->next;
         }
     }
     if(re ==  NULL)
     {
         printf("Can't Find!\n");
     }
     return (re);
 }

 void del(stud *p)
 {
     if(p == NULL|| (strcmp(p->name,"")==))
     {
         printf("is Null or head!\n");
         return;
     }
     else
     {
         p->next->prior = p->prior;
         p->prior->next = p->next;
         free(p);
     }
 }

 int length(stud *head)
 {
     int len=;
     stud *sp;
     if(head != NULL)
     {
         len = ;
         sp = head->next;
         while(sp)
         {
             sp = sp->next;
             len++;
         }
     }
     return len;
 }

 stud *insert(stud *head , char *name , int n)
 {
     stud *p,*nhead;
     int cnt=;
     if(strcmp(head->name,"") != )
     {
         cnt=;
     }
     nhead = head;
     if(n>length(head)||n<)
     {
         printf("It's Full or Error!\n");
         return NULL;
     }
     /*插入节点*/
     while(cnt<n)
     {
         head = head->next;
         cnt++;
     }
     p = (stud *)malloc(sizeof(stud));
     if(p != NULL)
     {
          strcpy(p->name,name);
          p->next = head->next;
          p->prior = head;

          if(head->next)/*双向链表操作这里很重要*/
              head->next->prior=p;
             head->next=p;
     }

     return nhead;
 }