c语言实现--双向循环链表操作

1，双向链表相当于两个单向循环链表。

2，双向链表的结点定义。

1 struct DULNode
2 {
3     int data;
4     struct DULNode * prior;
5     struct DULNode * next;
6 };
7 
8 typedef struct DULNode * linklist;

3，单循环链表的操作都适用于双循环链表。
4，双循环链表的操作集合仍在头文件defs.h中。

5，InitList操作。双循环链表初始化操作示意图

 1 #include"defs.h"
 2 
 3 void InitList(linklist *L) //改变头指针
 4 {
 5     *L = (linklist)malloc(sizeof(struct DULNode));
 6     if (*L == NULL)
 7         exit(0);
 8      (*L)->next = *L;
 9      (*L)->prior = *L; 
10 }

6，ClearList操作.

 1 #include"defs.h"
 2 
 3 void ClearList(linklist L)
 4 {
 5     linklist p = L->next;  //p指向链表第一个元素
 6    
 7     while (p != L)
 8      {
 9           p = p->next;  //p指向第二个元素
10         free(p->prior);
11      }
12      (*L)->next = *L;
13      (*L)->prior = *L;
14 }

ClearList.c

7,DestroyList操作

1 #include"defs.h"
2 
3 void DestroyList(linklist *L)
4 {
5     ClearList(*L);
6     free(*L);
7     *L = NULL;
8 }

DestroyList.c

8，ListEmpty操作

1 #include"defs.h"
2 
3 int ListEmpty(linklist L)
4 {
5     if (L->next == L && L->prior == L) //两个条件均要有
6         return 0;
7     else
8         return 1;
9 }

ListEmpty.c

9，ListLength操作

 1 #include"defs.h"
 2 
 3 int ListLength(linklist L)
 4 {
 5     linklist p = L->next;
 6     int j = 0;
 7     
 8     while (p != L)
 9     {
10         ++j;
11         p = p->next;
12     }
13     return j;
14 }

ListLength.c

10,GetElem操作

 1 #include"defs.h"
 2 
 3 int GetElem(linklist L, int i, int *e)
 4 {
 5      linklist p = L;
 6      int j = 0;
 7      if (i<1 || i>ListLength(L))
 8          exit(0);
 9      
10      while (j<i)   //找到第i个结点
11      {
12           ++j;
13           p = p->next;
14      }
15      *e = p->data;
16 }

GetElem.c

11,LocateElem操作, 没有找到返回-1

 1 #include"defs.h"
 2 
 3 int LocateElem(linklist L, int e)
 4 {
 5     linklist p = L->next;
 6     int j = 0;
 7 
 8     while (p != L)
 9     {
10         ++j;
11         if (p->data == e)
12              return j;
13     }
14     return -1;  
15 }

LocateElem.c

12，PriorElem操作

 1 #include"defs.h"
 2 
 3 int PriorElem(linklist L, int cur_e, int *pri_e)
 4 {
 5     linklist p = L->next->next;  //p指向第二个元素
 6  
 7    while (p != L)
 8     {
 9           if (p->data == cur_e)
10           {
11                 *pri_e = p->prior->data;
12                 return 0;
13           }
14     }
15     return 0;
16 }

PriorElem.c

13，NextElem操作

 1 #include"defs.h"
 2 
 3 int NextElem(linklist L, int cur_e, int *nex_e)
 4 {
 5     linklist p = L->next->next; 
 6     
 7      while (p != L)
 8      {
 9              if (p->prior->data == cur_e)
10              {
11                       *nex_e = p->data;
12                        return 0;
13              }
14      }
15      return 0;
16 }

NextElem.c

14，ListInsert操作

 1 #include"defs.h"
 2 
 3 int ListInsert(linklist L, int i, int e)
 4 {
 5       linklist p = L; //p指向头结点
 6      linklist q, s;
 7       int j = 0;
 8       if (i<1 || i>ListLength(L)+1)
 9          exit(0);
10   
11        while (j < i-1) //找到第i-1个结点
12      {
13            ++j;
14            p = p->next;
15        }
16        q = p->next;  //q指向第i个结点
17      
18      s = (linklist)malloc(sizeof(struct DULNode));
19       s->data = e;
20       
21       s->next = q;  //先改变向右的指针
22       p->next = s;   
23       s->prior = p;  //改变向左的指针
24       q->prior = s;
25       return 0;
26 }

ListInsert.c

15，ListDelete操作

 1 #include"defs.h"
 2 
 3 int ListDelete(linklist L, int i, int *e)
 4 {
 5     linklist p = L;
 6     linklist q;
 7     int j = 0;
 8     if (i<1 || i>ListLength(L))  //位置是否合理
 9         exit(0);
10     
11     while (j < i-1)    //找到第i-1个元素
12     {
13          ++j;
14          p = p->next;
15     }
16     q = p->next;  //p指向第i个结点
17    *e = q->data;
18     
19      p->next = q->next;
20      q->next->prior = p;
21      free(q);
22      return 0;
23 }

ListDelete.c

16，TravelList操作

 1 #include"defs.h"
 2 
 3 void TravelList(linklist L)
 4 {
 5     linklist p = L->next;
 6     int j = 0;
 7     while (p != L)
 8     {
 9           ++j;
10           printf("第%d个元素值为：%d
", j, p->data);
11           p = p->next;
12     }
13 }

TravelList.c

17，TravelListBack操作,逆序输出表中元素

 1 #include"defs.h"
 2 
 3 void TravelListBack(linklist L)
 4 {
 5      linklist p = L->prior;
 6      while (p != L)
 7      {
 8           printf("%d ", p->data);
 9           p = p->prior;
10      }
11      printf("
");
12 }

TravelListBack.c