双向链表的建立插入与删除

双向链表的建立插入与删除

/*注意因为建表时用了字符型数据所以输入数字时只能输0~9*/
#include<stdio.h>
#include<stdlib.h>

typedef struct node
{
	char data;
	struct node *pre;
	struct node *next;
}node, *list;

list TailCreat();                            //尾插法创建链表
void Insert(list head, int x, char value, int length);//向链表特定位置插入一个元素
void Delete(list head, int x, int length);   //删除特定位置的元素
int Length(list head);                       //链表的长度
void print(list head);                       //输出链表

int main(void)
{
	list head;
	int length, x;
	char value;

	head = TailCreat();
	length = Length(head);
	print(head);
	printf("\n");

	printf("请输入要插入的数：");
	scanf("%c",&value);
	printf("%c\n",value);
	printf("请输入要插入的位置：");
	scanf("%d",&x);
	printf("%d\n",x);
	Insert(head, x, value, length);          //向链表特定位置插入一个元素
	print(head);

	printf("请输入要删除元素的位置");
	scanf("%d",&x);
	Delete(head, x, length);                 //删除特定位置的元素
	print(head);

	return 0;
}

list TailCreat()                             //尾插法创建链表
{
	list head;
	node *p;
	char c;
	int flag = 1;

	head = (node *)malloc(sizeof(node));
	if(!head)
		printf("创建错误！");
	p = head;
	p->next = NULL;

	while(flag == 1)
	{
		node *w;
		w = (node *)malloc(sizeof(node));
		printf("请输入数据：");
		c = getchar();
		flushall();

		if(c != '$')
		{
			w->data = c;
			p->next = w;
			w->pre = p;
			p = w;

		}
		else
		{
			flag = 0;
			p->next = NULL;
		}
	}

	return head;
}

int Length(list head)                         //链表的长度
{
	node *p;
	int i = 0;

	for(p = head->next; p != NULL; p = p->next)
		i++;
	
	return i;
}

void Insert(list head, int x, char value, int length)//向链表特定位置插入一个元素
{
	node *p, *w;
	int i = 1;

	p = head->next;
	
	if(x > length)
	{
		printf("插入错误！\n");
	}
	else
	{
		w = (node *)malloc(sizeof(node));
		w->data = value;
		
		while(i < x)
		{
			p = p->next;
			i++;
		}
		
		w->pre = p->pre;
		p->pre->next = w;
		p->pre = w;
		w->next = p;
	}
}

void Delete(list head, int x, int length)         //删除特定位置的元素
{
	int i = 1;
	node *p;

	p = head->next;

	if(x > length)
	{
		printf("删除错误！\n");
	}
	else
	{	
		for(i = 1; i <x; i++)
		{
			p = p->next;	
		}
		p->pre->next = p->next;
		p->next->pre = p->pre;
		free(p);
	}
}

void print(list head)                              //输出链表
{
	node *p;

	for(p = head->next; p != NULL; p = p->next)
		printf("%c ",p->data);
	printf("\n");
}