通用链表操作接口函数

list.c

/*
*
*通用链表操作函数定义
**
*/

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

#include "list.h"
/*链表初始化*/
void list_init(List *list)
{
list->head = NULL;
list->tail = NULL;
list->len = 0;
}
/*是否为空链表*/
bool is_empty(List *list)
{
return (list->head == NULL);
}
/*创建链表*/
static struct node *make_node(void *data)    //把用户传递过来的数据打包为一个链表节点
{
struct node *n;

n = malloc(sizeof(struct node));
assert(n != NULL);

n->next = NULL;
n->data = data;

return n;
}
/*从链表的头节点插入新节点*/
void list_insert_at_head(List *list, void *data)    //头插法
{
struct node *n;
n = make_node(data);

if(list->head == NULL){ //如果是空链表
list->head = n;
list->tail = n;
}
else{                   //如果不是非空链表
n->next = list->head;
list->head = n;
}
list->len++;
}
/*从链表的中部index节点插入节点*/
void list_insert_at_index(List *list, void *data, long index)
{
long i = 1; //从1开始算
struct node *p, *n;

p = list->head;

while(p && i < index){
p = p->next;
i++;
}

if(p){ //如果链表遍历完了，计数i还没到index，说明第index个节点不存在。
n = make_node(data);
n->next = p->next;
p->next = n;
list->len++;
}
}
/*从链表的尾部节点插入新节点*/
void list_insert_at_tail(List *list, void *data)    //尾插法
{
struct node *n;
n = make_node(data);

if(is_empty(list)){    //如果是空链表
list->head = n;
list->tail = n;
}
else{                      //如果不是非空链表
list->tail->next = n;
list->tail = n;
}
list->len++;
}
/*
void list_insert(List *list, void *data)    //默认采用尾插法
{
#if 0
list_insert_at_tail(list, data);
#else
struct node *n;

n = make_node(data);

if(list->head == NULL){
list->head = n;
list->tail = n;
} else {
list->tail->next = n;
list->tail = n;
}
list->len++;
#endif
}
*/
/*从默认方式入新节点*/
void list_insert(List *list, void *data)
{
struct node *n;

n = make_node(data);

if(list->head == NULL){
list->head = n;
list->tail = n;
} else {
list->tail->next = n;
list->tail = n;
}
list->len++;
}
/*删除链表操作*/
void * list_delete(List *list, void *key, int (*compare)(const void *, const void *))
{
void *data;
struct node *n, *t;
n = list->head;

if(!compare(n->data, key)){    //如果要删除的节点为首节点
t = n;
data = n->data;
list->head = n->next;
free(t);
list->len--;
return data;
}

while(n->next != NULL){        //遍历查找符合条件的节点，删除之
if(compare(n->next->data, key) == 0){    //只删除第一个符合条件的节点。
t = n->next;
if(n->next == list->tail){
list->tail = n;
}
n->next = n->next->next;
data = t->data;
free(t);
list->len--;
return data;    //把删除的数据返回给用户，供用户后续的处理使用。
}
n = n->next;
}
return NULL;    //没找到匹配的节点，返回NULL
}
/*搜索节点*/
void *list_search(List *list, void *key, int (*compare)(const void *, const void *))
{
struct node *n;
n = list->head;

while(n){
if(!compare(n->data, key)){    //找到了，返回找到的数据
return n->data;
}
n = n->next;
}

return NULL;    //找不到，返回NULL
}

static struct node *find_min_node(List *list,
int (*compare)(const void *, const void *))
{
struct node *min, *n;

n = list->head;
min = list->head;

while(n){
if(compare(min->data, n->data) > 0){
min = n;
}
n = n->next;
}

return min;
}
//删除链表中的某个节点
static void delete_node(List *list, struct node *key)
{
struct node *n;

n = list->head;

if(n == key){
list->head = n->next;
return;
}

while(n->next){
if(n->next == key){
if(key == list->tail){
list->tail = n;
}
n->next = n->next->next;
return;
}
n = n->next;
}
}
//插入节点
static void insert_node(List *list, struct node *key)
{
if(list->head == NULL){
list->head = key;
list->tail = key;
}else{
list->tail->next = key;
list->tail = key;
}
}
//节点遍历
void list_sort(List *list,
int (*compare)(const void *, const void *))
{
List tmp;
struct node *n;

list_init(&tmp);

while(! is_empty(list)){
n = find_min_node(list, compare);
delete_node(list, n);
n->next = NULL;
insert_node(&tmp, n);
}
list->head = tmp.head;
list->tail = tmp.tail;
}
//链表遍历
void list_traverse(List *list, void (*handle)(void *))
{
struct node *p;
p = list->head;

while(p){
handle(p->data);
p = p->next;
}
}
//链表翻转
void list_reverse(List *list)
{
struct node *pre = NULL, *next, *p = list->head;

list->tail = list->head;    //tail指向head；
while(p){
next = p->next;
if(!next){  //当p->next为最后一个节点时，让head指向p->next
list->head = p;
}
//记录当前节点为pre，作为下一个节点的next.第一个节点为NULL，初始化时已定义。
p->next = pre;
pre = p;
p = next;
}
}
//获取链表长度
long list_get_lenth(List *list)
{
return (list->len);
}

void *list_get_element(List *list, int idx)
{
int i = 1;
struct node *n;
n = list->head;

while(n && i < idx){
i ++;
n = n->next;
}

if(n){
return n->data;
}

return NULL;
}
//链表销毁
void list_destroy(List *list, void (*destroy)(void *))
{
list->len = 0;
struct node *n, *t;
n = list->head;

while(n){
t = n->next;    //t只起一个记录n->next的功能，否则后面把n free掉之后，就找不到n->next了。
if(destroy){  //传递用户自定义的数据处理函数，为0时不执行
destroy(n->data);    //使用用户提供的destroy函数来释放用户传递过来的数据。
}
free(n);
n = t;  //把n free掉之后，再把t给n，相当于把n->next给n,如此循环遍历链表，挨个删除，
}
}

<span style="font-family: Arial, Helvetica, sans-serif;">main.c</span>

#include <stdio.h>

#include "list.h"
//测试数据结构
typedef struct test{
    int val1;
    float val2;
}test_t;
//显示（打印）链表数据
void handle(void *data)
{
    test_t *test = (test_t *)data;
    printf("val1:%d, val2:%f\n", test->val1, test->val2);
}
//比较两个数据的大小
int compare_int(const void *s1, const void *s2)
{
    test_t *data1 = (test_t *)s1;
    int *data2 =(int *)s2;

    return (data1->val1 - *data2);
}
//排序比较大小
int compare_int_sort(const void *s1, const void *s2)
{
    test_t *data1 = (test_t *)s1;
    test_t *data2 = (test_t *)s2;

    return (data1->val1 - data2->val1);
}
//打印链表
void print(List *list)
{
    printf("list len = %ld\n", list_get_lenth(list));
    if(!is_empty(list)){ 
        //test list_reverse
        list_traverse(list, handle);
    }
    else{
        printf("\tthe list is empty\n");
    }
}

int main(void)
{
//实例化List链表
    List list;
//初始化链表
    list_init(&list);
//测试数据test_t定义
    test_t test1 = {10, 10.5};
<span style="white-space:pre">	</span>test_t test2 = {20, 20.5};
<span style="white-space:pre">	</span>test_t test3 = {30, 30.5};
<span style="white-space:pre">	</span>test_t test4 = {40, 40.5};
<span style="white-space:pre">	</span>test_t test5 = {50, 50.5};
//默认从尾部插入tail
    //test list_insert
    printf("------insert(_at_tail)----\n");
    list_insert(&list, &test1);//10 10.5
    list_insert(&list, &test2);//20 20.5
    list_insert(&list, &test3);//30 30.5 
    print(&list);
//删除
    //test list_delete
    printf("------delete----\n");
    list_delete(&list, &test1.val1, compare_int);//函数指针compare_init
    print(&list);

    //test list_insert_at_head
    printf("------insert_at_head----\n");
    list_insert_at_head(&list, &test4);
    print(&list);

    //test list_insert_at_index
    printf("------insert_at_index(2)----\n");
    list_insert_at_index(&list, &test5, 2);
    print(&list);

    //test list_reverse
    printf("------reverse----\n");
    list_reverse(&list);
    print(&list);

    //test list_search
    int key = 20;
    test_t *ret;
    printf("------search----\n");
    ret = list_search(&list, &key, compare_int);
    printf("%d:%f\n", ret->val1, ret->val2);
    key = 50;
    ret = list_search(&list, &key, compare_int);
    printf("%d:%f\n", ret->val1, ret->val2);

    //test list_get_element 
    printf("------list_get_element----\n");
    ret = list_get_element(&list, 2);
    printf("%d:%f\n", ret->val1, ret->val2);
    ret = list_get_element(&list, 3);
    printf("%d:%f\n", ret->val1, ret->val2);

    //test list_sort
    printf("-----sort----\n");
    list_sort(&list, compare_int_sort);
    print(&list);
<span style="white-space:pre">	</span>//test if list is empty\n
<span style="white-space:pre">	</span>printf("-----check is_empty------");
<span style="white-space:pre">	</span>if(!is_empty(&list))
<span style="white-space:pre">	</span>{
<span style="white-space:pre">		</span>printf("list is not empty\n");
<span style="white-space:pre">		</span>printf("list len = %ld\n", list_get_lenth(&list));
<span style="white-space:pre">	</span>}
    //test list_destroy
    printf("-----destroy----\n");
    list_destroy(&list, NULL);
<span style="white-space:pre">	</span>//test is_empty
<span style="white-space:pre">	</span>printf("-----is_empty------");
<span style="white-space:pre">	</span>if(!is_empty(&list))
<span style="white-space:pre">	</span>{
<span style="white-space:pre">		</span>printf("list is not empty\n");
<span style="white-space:pre">		</span>printf("list len = %ld\n", list_get_lenth(&list));
<span style="white-space:pre">	</span>}

    return 0;
}