数据结构(3) - 双向链表

双向链表也叫双链表，是链表的一种，它的每个数据结点中都有两个指针，分别指向直接后继和直接前驱。所以，从双向链表中的任意一个结点开始，都可以很方便地访问它的前驱结点和后继结点。一般我们都构造双向循环链表。

代码如下：

double-list.c

/**
 * C data structure double linked list example.
 * 
 * License - MIT.
*/

#include "double-list.h"


/**
 * doulist_empty - Determine if the list is empty.
*/
bool doulist_empty(LPDOUBLELIST lpHead)
{
    return (lpHead == lpHead->next);
}


/**
 * doulist_show - Display list data.
*/
int doulist_show(LPDOUBLELIST lpHead)
{
    LPDOUBLELIST tmp;

    for (tmp = lpHead->next; tmp != lpHead; tmp = tmp->next)
        printf("%d ", tmp->data);

    printf("\n");

    return 0;
}


/**
 * doulist_insert - Add the specified data at specified node next location.
*/
int doulist_insert(LPDOUBLELIST lpHead, LPDOUBLELIST lpNode)
{
    lpNode->next        = lpHead->next;
    lpHead->next->prev  = lpNode;
    lpNode->prev        = lpHead;
    lpHead->next        = lpNode;

    return 0;
}


/**
 * doulist_insert_tail - Insert data to list tail.
*/
int doulist_insert_tail(LPDOUBLELIST lpHead, LPDOUBLELIST lpNode)
{
    lpNode->prev        = lpHead->prev;
    lpHead->prev->next  = lpNode;
    lpNode->next        = lpHead;
    lpHead->prev        = lpNode;

    return 0;
}


/**
 * doulist_del - Deletes the specified data by specified node next location.
*/
int doulist_del(LPDOUBLELIST lpNode)
{
    lpNode->prev->next = lpNode->next;
    lpNode->next->prev = lpNode->prev;

    return 0;
}


/**
 * doulist_init - Initialize double linked list.
*/
int doulist_init(LPDOUBLELIST *lpHead)
{
    *lpHead = (LPDOUBLELIST) malloc(sizeof(DOUBLELIST));
    if (NULL == *lpHead) {
        return -1;
    }

    (*lpHead)->next = *lpHead;
    (*lpHead)->prev = *lpHead;

    return 0;
}


/**
 * doulist_clear - clear double linked list.
*/
int doulist_clear(LPDOUBLELIST lpHead)
{
    LPDOUBLELIST tmp;

    if (!doulist_empty(lpHead)) {
        for (tmp = lpHead->next; tmp != lpHead; tmp = tmp->next) {
            doulist_del(tmp);
            free(tmp);
        }
    }

    tmp = NULL;

    free(lpHead);
    lpHead = NULL;

    return 0;
}

 

double-list.h

/**
 * C data structure double linked list example.
 * 
 * License - MIT.
*/

#ifndef __DOUBLE_LIST_H__
#define __DOUBLE_LIST_H__


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

typedef struct _DOUBLELIST{
    int data;
    struct _DOUBLELIST *prev, *next;
} DOUBLELIST, *LPDOUBLELIST;


bool doulist_empty      (LPDOUBLELIST lpHead);
int doulist_show        (LPDOUBLELIST lpHead);
int doulist_insert      (LPDOUBLELIST lpHead, LPDOUBLELIST lpNode);
int doulist_insert_tail (LPDOUBLELIST lpHead, LPDOUBLELIST lpNode);
int doulist_del         (LPDOUBLELIST lpNode);
int doulist_init        (LPDOUBLELIST *lpHead);
int doulist_clear       (LPDOUBLELIST lpHead);


#endif /* __DOUBLE_LIST_H__ */

 

main.c

/**
 * C data structure double linked list example.
 * 
 * License - MIT.
*/

#include <stdio.h>

#include "double-list.h"


#define MAX_TEST_NUM                10


/**
 * test_sort - Sort the data.
*/
int test_sort(LPDOUBLELIST lpHead)
{
    LPDOUBLELIST pos, tmp;

    pos = lpHead->prev;

    while (pos != lpHead)
    {
        if (1 == (pos->data % 2)) {
            pos = pos->prev;
        }
        else {
            tmp = pos;
            pos = pos->prev;

            doulist_del(tmp);
            doulist_insert_tail(lpHead, tmp);
        }
    }

    return 0;
}


/**
 * test_create - Create single list example.
*/
int test_create(LPDOUBLELIST lpHead)
{
    int i;
    LPDOUBLELIST newNode;

    for (i = 0; i < MAX_TEST_NUM; i++) {
        newNode = (LPDOUBLELIST) malloc(sizeof(DOUBLELIST));
        if (NULL == newNode) {
            return -1;
        }

        newNode->data = i + 1;
        doulist_insert_tail(lpHead, newNode);
    }

    return 0;
}


/**
 * Main function.
*/
int main(void)
{
    LPDOUBLELIST lphead = NULL;

    doulist_init(&lphead);

    test_create(lphead);
    doulist_show(lphead);

    test_sort(lphead);
    doulist_show(lphead);

    doulist_clear(lphead);

    return 0;
}

 

Makefile

# Makefile
CC = gcc
CFLAGS = -Wall -g -O0

SRC = main.c double-list.c

OBJ = doulist-test

$(OBJ) : $(SRC)
    $(CC) $(CFLAGS) -o $@ $^

clean:
    $(RM) $(OBJ) *.o *.*.sw?

 

完整代码请参考Github: [Link] [https://github.com/Phoebus-Ma/C-Helper/tree/main/Class-1/List.C]