本文实例讲述了C语言实现的循环单链表功能。，具体如下：
SClist.h
#ifndef __SCLIST_H__
#define __SCLIST_H__
#include<cstdio>
#include<malloc.h>
#include<assert.h>
typedef int ElemType;
typedef struct Node {
ElemType data;
struct Node *next;
}Node,*PNode;
typedef struct List {
PNode first;
PNode last;
size_t size;
}List;
void InitSClist(List *list);//初始化循环单链表
void push_back(List *list, ElemType x);//在循环单链表的末尾插入元素
void push_front(List *list, ElemType x);//在循环单链表的头部插入元素
void show_list(List *list);//打印循环单链表
void pop_back(List *list);//删除循环单链表的最后一个元素
void pop_front(List *list);//删除循环单链表的第一个元素
void insert_val(List *list, ElemType val);//将数据元素插入到循环单链表中（要求此时循环单链表中的数据元素顺序排列）
Node* find(List *list, ElemType x);//查找循环单链表中数据值为x的结点
int length(List *list);//求循环单链表的长度
void delete_val(List *list, ElemType x);//按值删除循环单链表中的某个数据元素
void sort(List *list);//对循环单链表进行排序
void reverse(List *list);//逆置循环单链表
void clear(List *list);//清除循环单链表
void destroy(List *list);//摧毁循环单链表
//优化
Node* _buynode(ElemType x);//创建结点
#endif
SClist.cpp
#include"SClist.h"
Node* _buynode(ElemType x) {
Node *s = (Node*)malloc(sizeof(Node));
assert(s != NULL);
s->data = x;
s->next = NULL;
return s;
}
void InitSClist(List *list) {
Node *s = (Node*)malloc(sizeof(Node));
assert(s != NULL);
list->first = list->last = s;
list->last->next = list->first;//让链表最后一个结点的指针域指向头结点，从而时链表循环
list->size = 0;
}
void push_back(List *list, ElemType x) {
Node *s = _buynode(x);
list->last->next = s;
list->last = s;
list->last->next = list->first;
list->size++;
}
void push_front(List *list, ElemType x) {
Node *s = _buynode(x);
s->next = list->first->next;
list->first->next = s;
if (list->last == list->first)
list->last = s;
list->size++;
}
void show_list(List *list) {
Node *p = list->first->next;
while (p != list->first) {
printf("%d->", p->data);
p = p->next;
}
printf("Nul.n");
}
void pop_back(List *list) {
if (list->size == 0) return;
Node *p = list->first;
while (p->next != list->last)
p = p->next;
free(list->last);
list->last = p;
list->last->next = list->first;
list->size--;
}
void pop_front(List *list) {
if (list->size == 0) return;
Node *p = list->first->next;
list->first->next = p->next;
if (list->size == 1)
list->last = list->first;
free(p);
list->size--;
}
void insert_val(List *list, ElemType x) {
Node *p = list->first;
while (p->next != list->last && p->next->data < x)
p = p->next;
if (p->next == list->last && p->next->data < x)
push_back(list, x);
else {
Node *s = _buynode(x);
s->next = p->next;
p->next = s;
list->size++;
}
}
Node* find(List *list, ElemType key) {
if (list->size == 0) return NULL;
Node *p = list->first->next;
while(p != list->first && p->data != key)
p = p->next;
if (p == list->first)
return NULL;
return p;
}
int length(List *list) {
return list->size;
}
void delete_val(List *list, ElemType x) {
if (list->size == 0) return;
Node *p = find(list, x);
if (p == NULL) {
printf("没有要删除的数据!n");
return;
}
if (p == list->last)
pop_back(list);
else {
Node *q = p->next;
p->data = q->data;
p->next = q->next;
free(q);
list->size--;
}
}
void sort(List *list) {
if (list->size == 0 || list->size == 1) return;
Node *s = list->first->next;
Node *q = s->next;
list->last->next = NULL;
list->last = s;
list->last->next = list->first;
while (q != NULL) {
s = q;
q = q->next;
Node *p = list->first;
while (p->next != list->last && p->next->data < s->data)
p = p->next;
if (p->next == list->last &&p->next->data < s->data) {
list->last->next = s;
list->last = s;
list->last->next = list->first;
}
else {
s->next = p->next;
p->next = s;
}
}
}
void reverse(List *list) {
if (list->size == 0 || list->size == 1) return;
Node *p = list->first->next;
Node *q = p->next;
list->last->next = NULL;
list->last = p;
list->last->next = list->first;
while (q != NULL) {
p = q;
q = q->next;
p->next = list->first->next;
list->first->next = p;
}
}
void clear(List *list) {
Node *p = list->first->next;
while (p != list->first) {
list->first->next = p->next;
free(p);
p = list->first->next;
}
list->last = list->first;
list->last->next = list->first;
list->size = 0;
}
void destroy(List *list) {
clear(list);
free(list->first);
list->first = list->last = NULL;
}
