单向循环链表【数据结构-朱战立】

/*这个程序是循环链表*/
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
typedef int bool;
#define true 1
#define false 0

typedef int DataType;
typedef struct node{
    DataType data;
    struct node *next;
}CurrNode;

//链表初始化
void CurrInit(CurrNode **head)
{
    if ((*head = (CurrNode*)malloc(sizeof(CurrNode))) == NULL)
    {
        exit(1);
    }
    (*head)->next = *head;//构造循环链表
}

//链表长度返回
int Currlength(CurrNode *head)
{
    CurrNode *per = head->next;
    int num = 0;

    while (per!= head)//出现中断错误？    //2018年8月15日 18:40:31 返回长度per!=head
    {
        per = per->next;
        num++;
    }
    return num;
}

//链表插入
int CurrInsert(CurrNode *head, int i, DataType x)
{
    CurrNode *per, *fin;
    int j = 0;

    if ((fin=(CurrNode*)malloc(sizeof(CurrNode)))==NULL)
    {
        exit(1);
    }
    per = head;                                       //2018年8月15日 18:48:36  如果per=head->next 那么链表将倒序
    while(per->next!=head&&/*per->next!=head&&*/j<i)  //2018年8月15日 18:41:38  判断条件不需要那么多

    {
        per = per->next;
        j++;
    }
    if (j!=i)
    {
        printf("插入位置错误！\n");
        return 0;
    }
    fin->data = x;

    fin->next = per->next;
    per->next = fin;
    return 1;
}

//链表删除
int CurrDelete(CurrNode *head, int i, DataType *x)
{
    CurrNode *per, *tmp;
    int j = 0;

    if ((tmp = (CurrNode*)malloc(sizeof(CurrNode))) == NULL)
    {
        exit(1);
    }
    per = head;
    while (per->next != head&&j<i)//删除不需要判断下一个节点是否存在
    {
        per = per->next;
        j++;
    }
    if (j != i)
    {
        printf("删除位置错误！\n");
        return 0;
    }
    *x = per->data;

    tmp = per->next;
    per->next = tmp->next;
    free(tmp);
    return 1;
}

//链表取出
int CurrGet(CurrNode *head, int i, DataType *x)
{
    CurrNode *per=head->next;
    int j = 0;

    while (per!=head&&j<i)
    {
        per = per->next;
        j++;//失误
    }
    if (j!=i)
    {
        printf("取出位置错误！\n");
        return 0;
    }
    *x = per->data;
    return 1;
}
//链表销毁
void CurrDestroy(CurrNode **head)
{
    CurrNode *per = *head, *tmp;
    if ((tmp = (CurrNode*)malloc(sizeof(CurrNode))) == NULL)
    {
        exit(1);
    }
    while (per->next!= *head)
    {
        tmp = per;
        per = per->next;
        free(tmp);
    }
    *head = NULL;
}

//判断是否构成循环链表
bool Currcheck(CurrNode* head)
{
    int nNumber = Currlength(head);

    CurrNode* pTemp = head;
    int i = 0;
    while (i < nNumber)
    {
        pTemp = pTemp->next;
        i++;
    }

    return (pTemp->next == head) ? true : false;
}

//主函数
int main()
{
    CurrNode *mylist;
    int i, x;

    CurrInit(&mylist);
    for ( i = 0; i < 10; i++)
    {
        if ((CurrInsert(mylist, i, i + 1)) == 0)
        {
            printf("插入位置错误！\n");
            return ;
        }
    }
    if ((CurrDelete(mylist, 5, &x)) == 0)
    {
        printf("删除位置错误！\n");
        return;
    }
    else
    {
        printf("删除数字：%d\n", x);
    }
    for ( i = 0; i < Currlength(mylist); i++)
    {
        if ((CurrGet(mylist, i, &x)) == 0)
        {
            printf("取出位置错误！\n");
            return;
        }
        else
        {
            printf("%d    ",x);
        }
    }
    printf("\n%s", (Currcheck(mylist) == 1 )? "是循环链表": "不是循环链表");
    CurrDestroy(&mylist);
    getchar();
    return 0;
}