C++链表

上个简单链表，写的有些难看，现在更改一下

https://liu-endong.blog.csdn.net/article/details/111934018

添加了删除尾结点，添加了删除头结点

#include <stdio.h>
#include<malloc.h>

#define LEN sizeof(struct List)

#if 1   //1开启 0关闭  VS2019开启 codeblocks关闭
#define scanf scanf_s
#endif


//定义节点
struct List
{
	int num;
	struct List* next;
};

struct List* creat()
{
	struct List* head = (struct List*)malloc(LEN);
	head->num = 0;  //存储链表长度，理论上头结点不需要数据域
	head->next = NULL;
	return head; 
}

//尾插法加一个节点
struct List* addList(List* head, int num)
{
	struct List* p;
	p = head;
	while (p->next)
	{
		p = p->next;
	}
	p->next = (struct List*)malloc(LEN);
	p->next->num = num;
	p->next->next = NULL;
	head->num++;
	printf("加入一个节点后链表长度 %d \n", head->num);
	return head;
}

//按存储的数据删除一个节点
struct List* deleteList(List* head, int num)
{
	struct List* p1, *p2;
	p1 = p2 = head;
	while (p1->next)
	{
		p2 = p1;
		p1 = p1->next;
		if (p1->num == num)
		{
			p2->next = p1->next;
			break;
		}
	}
	return head;
}

//删除尾巴节点
struct List* deleteTail(List* head)
{
	struct List* p1, *p2;
	p1 = p2 = head->next;
	while (p1->next)
	{
		p2 = p1;
		p1 = p1->next;
	}
	p2->next= NULL;
	return head;
}

//删除头节点
struct List* deleteHead(List* head)
{
	if (head->next)
	{
		head->next = head->next->next;
	}
	return head;
}


//遍历链表
void print(struct List* head)
{
	struct List* p;
	p = head->next;
	while (p != NULL)
	{
		printf("%d\n", p->num);
		p = p->next;
	}
}

int main()
{
	struct List* p;  //初始化一个链表
	p = creat();  //调用创建函数来创建一个链表
	deleteHead(p);
	print(p);
	printf("\n");
	p = addList(p, 1);  //从尾巴添加一个10
	p = addList(p, 2);  //从尾巴添加一个10
	p = addList(p, 3);  //从尾巴添加一个10
	p = addList(p, 4);  //从尾巴添加一个10
	p = addList(p, 5);  //从尾巴添加一个10
	p = addList(p, 6);  //从尾巴添加一个10
	p = addList(p, 7);  //从尾巴添加一个10
	p = addList(p, 8);  //从尾巴添加一个10
	p = addList(p, 9);  //从尾巴添加一个10
	p = addList(p, 10);  //从尾巴添加一个10
	print(p);
	printf("\n");
	p = deleteList(p, 3);   //删除元素为3的节点
	print(p);
	printf("\n");

	deleteTail(p);
	print(p);
	printf("\n");
	deleteHead(p);
	print(p);
}