C语言单向循环链表的建立

1.头文件

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

typedef struct Link{
    int data;
    struct Link *next;
}link;

2.功能函数

link *link_init(void)
{
    link *p = (link *)malloc(sizeof(link));
    p->next = p;
    return p;
}

//头插
void link_insert(link *head,int value)
{
    link *node = (link *)malloc(sizeof(link));
    node->next = head->next;
    head->next = node;
    node->data = value;
 
}

//尾插
void link_Insert(link *head,int value)
{
    link *node = (link *)malloc(sizeof(link));
    link *temp = head;
    while(temp->next != head)
    {
	temp = temp->next;
    }
    temp->next = node;
    node->data = value;
    node->next = head;
}

//删除
void link_del(link *head,int value)
{
    int ret = link_find(head,value);
    if(ret == -1)
    {
	printf("不存在这个数\n");
	return;
    }
    link *temp = head;
    link *q;
    int i;
    for(i = 0;i < ret;i++)
    {
	if(temp->next->data == value)
	{
	    q = temp->next;
	    temp->next = temp->next->next;
	    free(q);
	    break;
	}else
	{
	    temp = temp->next;
	}
    }

}
//修改
void link_change(link *head,int old,int new)
{
    int ret = link_find(head,old);
    if(ret == -1)
    {
	printf("不存在这个数\n");
	return;
    }
    link *temp = head->next;
    int i;
    for(i = 0;i < ret;i++)
    {
	if(temp->data == old)
	{
	    temp->data = new;
	}else
	{
	    temp = temp->next;
	}
    }


}

//查找
int link_find(link *head,int value)
{
    link *temp = head->next;
    int ret = 1;
    while(temp != head)
    {
	if(temp->data == value)
	{   
	    break;

	}else
	{
	    temp = temp->next;
	    ret++;
	}

    }
    if(temp == head)
    {
	return -1;
    }else
    {
	return ret;
    }

    
}

//逆转
void link_ni(link *head)
{
    link *newhead = head->next;
    link *q;
    head->next = NULL;
    while(newhead != NULL)
    {
	q = newhead;
	link_insert(head,q->data);
	newhead = newhead->next;
	free(q);
    } 
}

//中间插入
void link_zjinsert(link *head,int value)
{
    int ret = link_length(head);
    int x;
    printf("请选择插入数据的位置\n");
    scanf("%d",&x);
    if(x > ret && x < 0)
    {
	printf("插入位置不存在\n");
	return;
    }
    link *temp = (link *)malloc(sizeof(link));
    temp->data = value;
    link *q;
    int i;
    for(i = 0;i < x;i++)
    {
	if(i == x-1)
	{
	    temp->next = q->next;
	    q->next = temp;

	}else
	{
	    q = q->next;
	}
    }
}

//链表长度
int link_length(link *head)
{
    link *temp = head->next;
    int ret = 1;
    while(temp != head)
    {
	temp = temp->next;
	ret++;
    }
    return ret;

}

//找n出局
void link_n(link *head,int n)
{
    link *temp = head->next;
    link *q;
    int i = 1;
    while(head->next->next != head)
	{
	    
	    if(temp == head)
	    {
		temp = temp->next;
	    }
	    else
	    {
		temp = temp->next;
		i++;
	    }

	    if((i % n) == 0)
	    {	
		q = temp;
		temp = temp->next;
		free(q);
		i++;
		
	    }

	}
}

//打印
void link_show(link *head)
{
    link *temp = head->next;
    while(temp != head)
    {
	printf("%d  ",temp->data);
	temp = temp->next;
    }
    printf("\n");
}

3主函数

int main(void)
{
    link *head = link_init();
    link_insert(head,1);
    link_insert(head,2);
    link_insert(head,3);
    link_insert(head,4);
    link_insert(head,5);
    link_show(head);
    link_Insert(head,10);
    link_Insert(head,9);
    link_Insert(head,8);
    link_Insert(head,7);
    link_Insert(head,6);
    link_show(head);
    /*
    printf("请输入要查找的数\n");
    int n;
    scanf("%d",&n);
    int ret = link_find(head,n);
    if(ret == -1)
    {
	printf("查找失败\n");
    }else
    {
    printf("在链表第%d位\n",ret);
    }

    printf("请输入要删除的数\n");
    int a;
    scanf("%d",&a);
    link_del(head,a);
    link_show(head);

    int b,c;
    printf("请输入要修改的数，和更新的数\n ");
    scanf("%d%d",&b,&c);
    link_change(head,b,c);
    link_show(head);

    printf("链表逆转\n");
    link_ni(head);
    link_show(head);

    printf("中间插入\n");    
    link_zjinsert(head,29);
    link_show(head);
*/    
    link_n(head,3);
    link_show(head);
    
    return 0;
}